{
  "title": "Référentiel des unités et conventions — Convertisseur.com",
  "version": "2026-09-23-v19",
  "canonical": "https://www.convertisseur.com/referentiel-unites.html",
  "scope": "Sélection documentée de relations ; les décimales du moteur informatique ne constituent pas une mesure ni une certification.",
  "rows": [
    {
      "id": "centimetre",
      "family": "Longueur",
      "unit": "Centimètre",
      "relation": "1 cm = 0,01 m",
      "precision": "Exact : préfixe centi",
      "page": "/distance/metre-centimetre.html",
      "source": "https://www.bipm.org/en/publications/si-brochure",
      "sourceLabel": "BIPM — Brochure SI",
      "sourceLocator": "Tableau des préfixes SI : centi = 10⁻²",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/distance/metre-centimetre.html",
        "/distance/pied-centimetre.html",
        "/distance/pouce-centimetre.html"
      ]
    },
    {
      "id": "chaine",
      "family": "Longueur",
      "unit": "Chaîne de Gunter internationale",
      "relation": "1 ch = 20,1168 m",
      "precision": "Exact : 66 pieds internationaux",
      "page": "/distance/chaine-metre.html",
      "source": "https://www.nist.gov/pml/us-surveyfoot/revised-unit-conversion-factors",
      "sourceLabel": "NIST — Revised Unit Conversion Factors",
      "sourceLocator": "Ligne chain : colonne du pied international, 66 ft = 100 li = 20,1168 m",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/distance/chaine-metre.html"
      ]
    },
    {
      "id": "kilometre",
      "family": "Longueur",
      "unit": "Kilomètre",
      "relation": "1 km = 1 000 m",
      "precision": "Exact : préfixe kilo",
      "page": "/distance/kilometre-metre.html",
      "source": "https://www.bipm.org/en/publications/si-brochure",
      "sourceLabel": "BIPM — Brochure SI",
      "sourceLocator": "Tableau des préfixes SI : kilo = 10³",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/distance/kilometre-metre.html",
        "/distance/kilometre-mille.html",
        "/distance/kilometre-pied.html",
        "/distance/kilometre-pouce.html",
        "/distance/metre-kilometre.html",
        "/distance/mille-nautique-kilometre.html"
      ]
    },
    {
      "id": "mile",
      "family": "Longueur",
      "unit": "Mile terrestre international",
      "relation": "1 mi = 1 609,344 m",
      "precision": "Exact ; ne pas confondre avec le mille marin",
      "page": "/distance/kilometre-mille.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "mile",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/distance/kilometre-mille.html"
      ]
    },
    {
      "id": "mille-marin",
      "family": "Longueur",
      "unit": "Mille marin international",
      "relation": "1 nmi = 1 852 m",
      "precision": "Exact",
      "page": "/distance/mille-nautique-kilometre.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "mile, nautical",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/distance/mille-nautique-kilometre.html"
      ]
    },
    {
      "id": "millimetre",
      "family": "Longueur",
      "unit": "Millimètre",
      "relation": "1 mm = 0,001 m",
      "precision": "Exact : préfixe milli",
      "page": "/distance/pouce-millimetre.html",
      "source": "https://www.bipm.org/en/publications/si-brochure",
      "sourceLabel": "BIPM — Brochure SI",
      "sourceLocator": "Tableau des préfixes SI : milli = 10⁻³",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/distance/pouce-millimetre.html"
      ]
    },
    {
      "id": "pied",
      "family": "Longueur",
      "unit": "Pied international",
      "relation": "1 ft = 0,3048 m",
      "precision": "Exact ; hors anciens pieds d’arpentage",
      "page": "/distance/pied-metre.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "foot",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/distance/kilometre-pied.html",
        "/distance/pied-centimetre.html",
        "/distance/pied-metre.html",
        "/distance/pouce-pied.html"
      ]
    },
    {
      "id": "pouce",
      "family": "Longueur",
      "unit": "Pouce international",
      "relation": "1 in = 0,0254 m",
      "precision": "Exact",
      "page": "/distance/pouce-metre.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "inch",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/distance/kilometre-pouce.html",
        "/distance/pouce-centimetre.html",
        "/distance/pouce-metre.html",
        "/distance/pouce-millimetre.html",
        "/distance/pouce-pied.html"
      ]
    },
    {
      "id": "yard",
      "family": "Longueur",
      "unit": "Yard international",
      "relation": "1 yd = 0,9144 m",
      "precision": "Exact",
      "page": "/distance/verge-metre.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "yard",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/distance/verge-metre.html"
      ]
    },
    {
      "id": "carat",
      "family": "Masse",
      "unit": "Carat métrique",
      "relation": "1 ct = 0,0002 kg",
      "precision": "Exact ; sans rapport avec le titre de l’or",
      "page": "/poids/carat-gramme.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "carat",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/poids/carat-gramme.html"
      ]
    },
    {
      "id": "gramme",
      "family": "Masse",
      "unit": "Gramme",
      "relation": "1 g = 0,001 kg",
      "precision": "Exact",
      "page": "/poids/gramme-kilogramme.html",
      "source": "https://www.bipm.org/en/publications/si-brochure",
      "sourceLabel": "BIPM — Brochure SI",
      "sourceLocator": "Unité de masse kilogramme et préfixes",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/poids/carat-gramme.html",
        "/poids/gramme-kilogramme.html",
        "/poids/gramme-milligramme.html",
        "/poids/gramme-once.html",
        "/poids/livre-gramme.html"
      ]
    },
    {
      "id": "livre",
      "family": "Masse",
      "unit": "Livre avoirdupois internationale",
      "relation": "1 lb = 0,45359237 kg",
      "precision": "Exact",
      "page": "/poids/kilogramme-livre.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "pound",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/poids/kilogramme-livre.html",
        "/poids/livre-gramme.html",
        "/poids/ounce-livre.html",
        "/poids/tonne-livre.html"
      ]
    },
    {
      "id": "long-ton",
      "family": "Masse",
      "unit": "Long ton UK",
      "relation": "1 long ton = 1 016,0469088 kg",
      "precision": "Exact : 2 240 lb",
      "page": "/poids/tonne-long-ton.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "ton, long",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/poids/tonne-long-ton.html"
      ]
    },
    {
      "id": "microgramme",
      "family": "Masse",
      "unit": "Microgramme",
      "relation": "1 µg = 0,001 mg",
      "precision": "Exact : préfixes micro et milli",
      "page": "/poids/microgramme-milligramme.html",
      "source": "https://www.bipm.org/en/publications/si-brochure",
      "sourceLabel": "BIPM — Brochure SI",
      "sourceLocator": "Tableau des préfixes SI : micro = 10⁻⁶ ; milli = 10⁻³",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/poids/microgramme-milligramme.html"
      ]
    },
    {
      "id": "once-masse",
      "family": "Masse",
      "unit": "Once avoirdupois",
      "relation": "1 oz = 0,028349523125 kg",
      "precision": "Exact : 1/16 lb ; hors once troy",
      "page": "/poids/gramme-once.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "ounce, avoirdupois",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/poids/gramme-once.html",
        "/poids/ounce-livre.html"
      ]
    },
    {
      "id": "short-ton",
      "family": "Masse",
      "unit": "Short ton US",
      "relation": "1 short ton = 907,18474 kg",
      "precision": "Exact : 2 000 lb",
      "page": "/poids/tonne-short-ton.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "ton, short",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/poids/tonne-short-ton.html"
      ]
    },
    {
      "id": "stone",
      "family": "Masse",
      "unit": "Stone",
      "relation": "1 st = 6,35029318 kg",
      "precision": "Exact : 14 lb",
      "page": "/poids/kilogramme-stone.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "pound ; relation stone = 14 lb",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/poids/kilogramme-stone.html"
      ]
    },
    {
      "id": "tonne",
      "family": "Masse",
      "unit": "Tonne métrique",
      "relation": "1 t = 1 000 kg",
      "precision": "Exact ; distincte des tons US et UK",
      "page": "/poids/tonne-kilogramme.html",
      "source": "https://www.bipm.org/en/publications/si-brochure",
      "sourceLabel": "BIPM — Brochure SI",
      "sourceLocator": "Unités hors SI dont l’usage est accepté avec le SI : tonne",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/poids/tonne-kilogramme.html",
        "/poids/tonne-livre.html",
        "/poids/tonne-long-ton.html",
        "/poids/tonne-short-ton.html"
      ]
    },
    {
      "id": "acre",
      "family": "Surface",
      "unit": "Acre international",
      "relation": "1 acre = 4 046,8564224 m²",
      "precision": "Exact : 43 560 pieds internationaux carrés",
      "page": "/mathematique/acre-metre-carre.html",
      "source": "https://www.nist.gov/pml/us-surveyfoot/revised-unit-conversion-factors",
      "sourceLabel": "NIST — Revised Unit Conversion Factors",
      "sourceLocator": "Ligne acre : colonne du pied international, 43 560 ft² = 4 046,8564224 m² ; colonne survey foot distincte",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/mathematique/acre-metre-carre.html",
        "/mathematique/acre-pied-carre.html",
        "/mathematique/hectare-acre.html"
      ]
    },
    {
      "id": "hectare",
      "family": "Surface",
      "unit": "Hectare",
      "relation": "1 ha = 10 000 m²",
      "precision": "Exact",
      "page": "/mathematique/hectare-metre-carre.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "hectare",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/mathematique/hectare-acre.html",
        "/mathematique/hectare-metre-carre.html"
      ]
    },
    {
      "id": "pied-carre",
      "family": "Surface",
      "unit": "Pied carré international",
      "relation": "1 ft² = 0,09290304 m²",
      "precision": "Exact : (0,3048 m)²",
      "page": "/mathematique/metre-carre-pied-carre.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "foot, square",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/mathematique/acre-pied-carre.html",
        "/mathematique/metre-carre-pied-carre.html"
      ]
    },
    {
      "id": "pouce-carre",
      "family": "Surface",
      "unit": "Pouce carré international",
      "relation": "1 in² = 6,4516 cm²",
      "precision": "Exact : (2,54 cm)² ; le facteur doit être élevé au carré",
      "page": "/mathematique/centimetre-carre-pouce-carre.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "inch, square",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/mathematique/centimetre-carre-pouce-carre.html"
      ]
    },
    {
      "id": "gallon-imperial",
      "family": "Volume",
      "unit": "Gallon impérial",
      "relation": "1 gal imp = 4,54609 L",
      "precision": "Exact",
      "page": "/mathematique/gallon-us-imperial.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "gallon, Canadian and U.K.",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/mathematique/gallon-us-imperial.html"
      ]
    },
    {
      "id": "gallon-us",
      "family": "Volume",
      "unit": "Gallon liquide US",
      "relation": "1 gal US = 3,785411784 L",
      "precision": "Exact ; hors gallon sec",
      "page": "/mathematique/litre-gallon.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "gallon, U.S.",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/mathematique/litre-gallon.html"
      ]
    },
    {
      "id": "litre",
      "family": "Volume",
      "unit": "Litre",
      "relation": "1 L = 0,001 m³",
      "precision": "Exact",
      "page": "/mathematique/metre-cube-litre.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "liter",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/mathematique/litre-gallon.html",
        "/mathematique/litre-millilitre.html",
        "/mathematique/litre-once.html",
        "/mathematique/litre-pinte.html",
        "/mathematique/metre-cube-litre.html"
      ]
    },
    {
      "id": "millilitre",
      "family": "Volume",
      "unit": "Millilitre",
      "relation": "1 mL = 0,001 L",
      "precision": "Exact ; 1 mL = 1 cm³",
      "page": "/mathematique/litre-millilitre.html",
      "source": "https://www.bipm.org/en/publications/si-brochure",
      "sourceLabel": "BIPM — Brochure SI",
      "sourceLocator": "Litre et préfixe milli",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/mathematique/litre-millilitre.html",
        "/mathematique/millilitre-once.html"
      ]
    },
    {
      "id": "once-liquide-us",
      "family": "Volume",
      "unit": "Once liquide US",
      "relation": "1 fl oz US = 29,5735295625 mL",
      "precision": "Exact : 1/128 gallon liquide US",
      "page": "/mathematique/millilitre-once.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "ounce, fluid, U.S.",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/mathematique/litre-once.html",
        "/mathematique/millilitre-once.html"
      ]
    },
    {
      "id": "once-liquide-imperiale",
      "family": "Volume",
      "unit": "Once liquide impériale",
      "relation": "1 fl oz imp = 28,4130625 mL",
      "precision": "Exact : 1/160 gallon impérial",
      "page": "/mathematique/litre-once.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "ounce, fluid, Canadian and U.K.",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/mathematique/litre-once.html"
      ]
    },
    {
      "id": "pied-cube",
      "family": "Volume",
      "unit": "Pied cube international",
      "relation": "1 ft³ = 0,028316846592 m³",
      "precision": "Exact : (0,3048 m)³",
      "page": "/mathematique/metre-cube-pied-cube.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "foot, cubic",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/mathematique/metre-cube-pied-cube.html"
      ]
    },
    {
      "id": "pinte-imperiale",
      "family": "Volume",
      "unit": "Pinte impériale",
      "relation": "1 pt imp = 568,26125 mL",
      "precision": "Exact : 1/8 gallon impérial",
      "page": "/mathematique/gallon-us-imperial.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "pint (Canadian and U.K.)",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/mathematique/gallon-us-imperial.html"
      ]
    },
    {
      "id": "pinte-us",
      "family": "Volume",
      "unit": "Pinte liquide US",
      "relation": "1 pt US = 473,176473 mL",
      "precision": "Exact : 1/8 gallon liquide US ; hors pinte sèche",
      "page": "/mathematique/litre-pinte.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "pint, liquid (U.S.)",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/mathematique/litre-pinte.html"
      ]
    },
    {
      "id": "annee-moyenne",
      "family": "Durée",
      "unit": "Année moyenne grégorienne",
      "relation": "1 année moyenne = 365,2425 jours",
      "precision": "Moyenne exacte du cycle de 400 ans ; pas une année civile particulière",
      "page": "/temps/annee-jour.html",
      "source": "https://aa.usno.navy.mil/faq/leap_years",
      "sourceLabel": "US Naval Observatory — Leap Years",
      "sourceLocator": "146 097 jours répartis sur 400 années",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/temps/annee-jour.html",
        "/temps/mois-annee.html"
      ]
    },
    {
      "id": "heure",
      "family": "Durée",
      "unit": "Heure",
      "relation": "1 h = 3 600 s",
      "precision": "Exact",
      "page": "/temps/heure-minute.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "hour",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/temps/heure-jour.html",
        "/temps/heure-minute.html",
        "/temps/heure-semaine.html",
        "/temps/heures-decimales-minutes.html",
        "/temps/jour-heure.html"
      ]
    },
    {
      "id": "jour",
      "family": "Durée",
      "unit": "Jour comme durée nominale",
      "relation": "1 d = 86 400 s",
      "precision": "Convention de durée ; une journée civile locale peut différer",
      "page": "/temps/jour-heure.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "day",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/temps/annee-jour.html",
        "/temps/heure-jour.html",
        "/temps/jour-heure.html",
        "/temps/jour-mois.html",
        "/temps/jour-semaine.html",
        "/temps/semaine-jour.html"
      ]
    },
    {
      "id": "minute",
      "family": "Durée",
      "unit": "Minute",
      "relation": "1 min = 60 s",
      "precision": "Exact ; unité de durée",
      "page": "/temps/minute-seconde.html",
      "source": "https://www.bipm.org/en/publications/si-brochure",
      "sourceLabel": "BIPM — Brochure SI",
      "sourceLocator": "Unités hors SI acceptées : minute",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/temps/heure-minute.html",
        "/temps/heures-decimales-minutes.html",
        "/temps/minute-seconde.html",
        "/temps/seconde-minute.html"
      ]
    },
    {
      "id": "mois-moyen",
      "family": "Durée",
      "unit": "Mois moyen grégorien",
      "relation": "1 mois moyen = 30,436875 jours",
      "precision": "Moyenne de 400 années ; pas un mois du calendrier",
      "page": "/temps/mois-calendrier.html",
      "source": "https://aa.usno.navy.mil/faq/leap_years",
      "sourceLabel": "US Naval Observatory — Leap Years",
      "sourceLocator": "cycle grégorien : 146 097 jours / 4 800 mois",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/temps/jour-mois.html",
        "/temps/mois-annee.html",
        "/temps/mois-calendrier.html",
        "/temps/semaine-mois.html"
      ]
    },
    {
      "id": "kmh-ms",
      "family": "Vitesse",
      "unit": "Kilomètre par heure",
      "relation": "1 km/h = 5/18 m/s",
      "precision": "Fraction exacte ; écriture décimale arrondie",
      "page": "/vitesse/kilometre-heure-metre-seconde.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "kilometer per hour",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/vitesse/kilometre-heure-metre-seconde.html",
        "/vitesse/kilometre-heure-mph.html",
        "/vitesse/kilometre-minute-kilometre-heure.html",
        "/vitesse/mach-kilometre-heure.html",
        "/vitesse/metre-minute-kilometre-heure.html",
        "/vitesse/mile-minute-kilometre-heure.html",
        "/vitesse/noeud-kilometre-heure.html"
      ]
    },
    {
      "id": "mph",
      "family": "Vitesse",
      "unit": "Mile terrestre international par heure",
      "relation": "1 mph = 0,44704 m/s",
      "precision": "Exact : 1 609,344 m / 3 600 s",
      "page": "/vitesse/mph-metre-seconde.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "mile per hour",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/vitesse/kilometre-heure-mph.html",
        "/vitesse/mph-metre-seconde.html"
      ]
    },
    {
      "id": "noeud",
      "family": "Vitesse",
      "unit": "Nœud",
      "relation": "1 kn = 1,852 km/h",
      "precision": "Exact : un mille marin par heure",
      "page": "/vitesse/noeud-kilometre-heure.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "knot",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/vitesse/noeud-kilometre-heure.html",
        "/vitesse/noeud-metre-seconde.html"
      ]
    },
    {
      "id": "pied-seconde",
      "family": "Vitesse",
      "unit": "Pied international par seconde",
      "relation": "1 ft/s = 0,3048 m/s",
      "precision": "Exact",
      "page": "/vitesse/pied-seconde-metre-seconde.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "foot per second",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/vitesse/pied-seconde-metre-seconde.html"
      ]
    },
    {
      "id": "atmosphere",
      "family": "Pression",
      "unit": "Atmosphère normale",
      "relation": "1 atm = 101 325 Pa",
      "precision": "Exact ; ne donne pas la pression atmosphérique locale",
      "page": "/science/atmosphere-bar.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "atmosphere, standard",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/science/atmosphere-bar.html"
      ]
    },
    {
      "id": "bar",
      "family": "Pression",
      "unit": "Bar",
      "relation": "1 bar = 100 000 Pa",
      "precision": "Exact ; préciser absolu ou relatif dans le contexte",
      "page": "/science/pascal-bar.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "bar",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/science/atmosphere-bar.html",
        "/science/bar-psi.html",
        "/science/pascal-bar.html"
      ]
    },
    {
      "id": "psi",
      "family": "Pression",
      "unit": "Livre-force par pouce carré",
      "relation": "1 psi = 8 896 443 230 521 / 1 290 320 000 Pa",
      "precision": "Fraction exacte avec livre internationale et pesanteur normale ; préciser absolu ou relatif",
      "page": "/science/bar-psi.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "pound-force per square inch ; 0,45359237 × 9,80665 / 0,0254²",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/science/bar-psi.html",
        "/science/kpa-psi.html"
      ]
    },
    {
      "id": "torr",
      "family": "Pression",
      "unit": "Torr",
      "relation": "1 Torr = 101 325 / 760 Pa",
      "precision": "Fraction exacte selon cette définition ; décimal arrondi",
      "page": "/science/torr-pascal.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "torr",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/science/torr-pascal.html"
      ]
    },
    {
      "id": "kilogramme-force",
      "family": "Force",
      "unit": "Kilogramme-force",
      "relation": "1 kgf = 9,80665 N",
      "precision": "Exact sous pesanteur normale ; ne mesure pas une masse",
      "page": "/science/newton-kilogramme-force.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "kilogram-force",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/science/newton-kilogramme-force.html"
      ]
    },
    {
      "id": "calorie",
      "family": "Énergie",
      "unit": "Calorie thermochimique",
      "relation": "1 calₜₕ = 4,184 J",
      "precision": "Exact ; d’autres calories existent",
      "page": "/science/joule-calorie.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "calorie, thermochemical",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/science/joule-calorie.html"
      ]
    },
    {
      "id": "kilowattheure",
      "family": "Énergie",
      "unit": "Kilowattheure",
      "relation": "1 kWh = 3 600 000 J",
      "precision": "Exact : puissance × durée",
      "page": "/science/kilowattheure-joule.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "kilowatthour",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/science/joule-kilowattheure.html",
        "/science/kilowattheure-joule.html"
      ]
    },
    {
      "id": "cheval-vapeur",
      "family": "Puissance",
      "unit": "Cheval-vapeur métrique",
      "relation": "1 ch = 735,49875 W",
      "precision": "Exact : 75 kgf·m/s ; distinct du horsepower mécanique",
      "page": "/science/watt-cheval-vapeur.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "horsepower, metric",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/science/kilowatt-cheval-vapeur.html",
        "/science/watt-cheval-vapeur.html"
      ]
    },
    {
      "id": "kilohertz",
      "family": "Fréquence",
      "unit": "Kilohertz",
      "relation": "1 kHz = 1 000 Hz",
      "precision": "Exact : préfixe kilo",
      "page": "/science/kilohertz-hertz.html",
      "source": "https://www.bipm.org/en/publications/si-brochure",
      "sourceLabel": "BIPM — Brochure SI",
      "sourceLocator": "Préfixes SI ; hertz = s⁻¹",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/science/gigahertz-kilohertz.html",
        "/science/kilohertz-hertz.html",
        "/science/kilohertz-megahertz.html"
      ]
    },
    {
      "id": "megahertz",
      "family": "Fréquence",
      "unit": "Mégahertz",
      "relation": "1 MHz = 1 000 000 Hz",
      "precision": "Exact : préfixe méga",
      "page": "/science/megahertz-hertz.html",
      "source": "https://www.bipm.org/en/publications/si-brochure",
      "sourceLabel": "BIPM — Brochure SI",
      "sourceLocator": "Préfixes SI : méga = 10⁶",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/science/kilohertz-megahertz.html",
        "/science/megahertz-gigahertz.html",
        "/science/megahertz-hertz.html"
      ]
    },
    {
      "id": "celsius-fahrenheit",
      "family": "Température",
      "unit": "Celsius et Fahrenheit",
      "relation": "t(°F) = t(°C) × 9/5 + 32",
      "precision": "Relation exacte pour ces échelles",
      "page": "/temperature/celsius-fahrenheit.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "degree Fahrenheit",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/temperature/celsius-fahrenheit.html"
      ]
    },
    {
      "id": "kelvin-celsius",
      "family": "Température",
      "unit": "Celsius et kelvin",
      "relation": "T(K) = t(°C) + 273,15",
      "precision": "Décalage exact ; température absolue ≥ 0 K",
      "page": "/temperature/celsius-kelvin.html",
      "source": "https://www.bipm.org/en/publications/si-brochure",
      "sourceLabel": "BIPM — Brochure SI, température Celsius",
      "sourceLocator": "BIPM : température Celsius",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/temperature/celsius-kelvin.html"
      ]
    },
    {
      "id": "ecart-temperature",
      "family": "Température",
      "unit": "Écart de température",
      "relation": "Δt(°F) = Δt(°C) × 9/5",
      "precision": "Sans ajout de 32 pour un écart",
      "page": "/temperature/ecart-celsius-fahrenheit.html",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8",
      "sourceLabel": "NIST SP 811, annexe B.8",
      "sourceLocator": "degree Fahrenheit ; intervalle de température",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/temperature/ecart-celsius-fahrenheit.html"
      ]
    },
    {
      "id": "degre",
      "family": "Angle",
      "unit": "Degré d’angle",
      "relation": "1° = π/180 rad",
      "precision": "Relation exacte ; approximation seulement lors de l’évaluation décimale de π",
      "page": "/mathematique/degre-radian.html",
      "source": "https://www.bipm.org/en/publications/si-brochure",
      "sourceLabel": "BIPM — Brochure SI",
      "sourceLocator": "Unités hors SI acceptées : degré d’angle",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/mathematique/degre-radian.html"
      ]
    },
    {
      "id": "gibioctet",
      "family": "Données",
      "unit": "Gibioctet",
      "relation": "1 Gio = 1 073 741 824 octets",
      "precision": "Exact : 2³⁰ octets ; distinct du Go décimal",
      "page": "/fichiers/unites-numeriques.html",
      "source": "https://physics.nist.gov/cuu/Units/binary.html",
      "sourceLabel": "NIST — Binary prefixes",
      "sourceLocator": "NIST : préfixes binaires",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/fichiers/unites-numeriques.html"
      ]
    },
    {
      "id": "gigaoctet",
      "family": "Données",
      "unit": "Gigaoctet décimal",
      "relation": "1 Go = 1 000 000 000 octets",
      "precision": "Exact : 10⁹ octets ; distinct du Gio",
      "page": "/fichiers/unites-numeriques.html",
      "source": "https://physics.nist.gov/cuu/Units/binary.html",
      "sourceLabel": "NIST — Binary prefixes",
      "sourceLocator": "NIST : préfixes décimaux et binaires",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/fichiers/unites-numeriques.html"
      ]
    },
    {
      "id": "mebioctet",
      "family": "Données",
      "unit": "Mébioctet",
      "relation": "1 Mio = 1 048 576 octets",
      "precision": "Exact : 2²⁰ octets ; distinct du Mo",
      "page": "/fichiers/unites-numeriques.html",
      "source": "https://physics.nist.gov/cuu/Units/binary.html",
      "sourceLabel": "NIST — Binary prefixes",
      "sourceLocator": "mebi = 2²⁰",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/fichiers/unites-numeriques.html"
      ]
    },
    {
      "id": "megaoctet",
      "family": "Données",
      "unit": "Mégaoctet décimal",
      "relation": "1 Mo = 1 000 000 octets",
      "precision": "Exact : 10⁶ octets ; distinct du Mio",
      "page": "/fichiers/unites-numeriques.html",
      "source": "https://physics.nist.gov/cuu/Units/binary.html",
      "sourceLabel": "NIST — Binary prefixes",
      "sourceLocator": "Préfixes décimaux et binaires",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/fichiers/unites-numeriques.html"
      ]
    },
    {
      "id": "octet",
      "family": "Données",
      "unit": "Octet",
      "relation": "1 octet = 8 bits",
      "precision": "Exact ; ne pas confondre quantité et débit par seconde",
      "page": "/fichiers/unites-numeriques.html",
      "source": "https://physics.nist.gov/cuu/Units/binary.html",
      "sourceLabel": "NIST — Binary prefixes",
      "sourceLocator": "Byte : 8 bits",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/fichiers/unites-numeriques.html"
      ]
    },
    {
      "id": "horsepower-mecanique",
      "family": "Puissance",
      "unit": "Horsepower mécanique",
      "relation": "1 hp mécanique = 550 ft·lbf/s = 745,69987158227022 W",
      "precision": "Exact par définition, à distinguer du hp électrique et du cheval métrique",
      "page": "/science/kilowatt-cheval-vapeur.html#outil-complementaire",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b9",
      "sourceLabel": "NIST SP 811, annexe B.9",
      "sourceLocator": "Power : horsepower (550 ft·lbf/s). Valeur développée depuis le pied international, la livre internationale et gₙ = 9,80665 m/s² ; la table NIST affiche un arrondi.",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/science/watt-cheval-vapeur.html",
        "/science/kilowatt-cheval-vapeur.html"
      ]
    },
    {
      "id": "kilocalorie-thermochimique",
      "family": "Énergie",
      "unit": "Kilocalorie thermochimique",
      "relation": "1 kcal_th = 1 000 cal_th = 4 184 J = 4,184 kJ",
      "precision": "Exact, convention thermochimique ; la calorie IT est différente",
      "page": "/science/joule-calorie.html#outil-complementaire",
      "source": "https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b9",
      "sourceLabel": "NIST SP 811, annexe B.9",
      "sourceLocator": "Energy : kilocalorie_th ; préfixe kilo = 10³",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/science/joule-calorie.html"
      ]
    },
    {
      "id": "cuillere-cafe-metrique",
      "family": "Volume",
      "unit": "Cuillère à café métrique",
      "relation": "1 cuillère à café métrique = 5 mL",
      "precision": "Exact dans la convention métrique choisie ; la contenance du doseur réel doit être vérifiée",
      "page": "/autres/cuillere-cafe-millilitre.html",
      "source": "https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=904045",
      "sourceLabel": "NIST SP 430 — Household Weights and Measures",
      "sourceLocator": "Mesures métriques de cuisine : metric teaspoon de 5 mL et metric tablespoon de 15 mL",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/autres/cuillere-cafe-millilitre.html"
      ]
    },
    {
      "id": "cuillere-soupe-metrique",
      "family": "Volume",
      "unit": "Cuillère à soupe métrique",
      "relation": "1 cuillère à soupe métrique = 15 mL",
      "precision": "Exact dans la convention métrique choisie ; la contenance du doseur réel doit être vérifiée",
      "page": "/autres/cuillere-soupe-millilitre.html",
      "source": "https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=904045",
      "sourceLabel": "NIST SP 430 — Household Weights and Measures",
      "sourceLocator": "Mesures métriques de cuisine : metric teaspoon de 5 mL et metric tablespoon de 15 mL",
      "reviewed": "2026-09-23",
      "relatedPages": [
        "/autres/cuillere-soupe-millilitre.html"
      ]
    }
  ]
}