{
 "source": "NIST SP 811; NIST Handbook 44 App. C; BIPM SI Brochure 9th ed.",
 "updated": "2026-11-03",
 "categories": [
  {
   "id": "length",
   "base": "meter",
   "url": "https://calcora.dev/length/",
   "units": [
    {
     "id": "millimeter",
     "slug": "millimeters",
     "symbol": "mm",
     "name": "millimeter",
     "system": "si",
     "factor": 0.001,
     "exact": true
    },
    {
     "id": "centimeter",
     "slug": "centimeters",
     "symbol": "cm",
     "name": "centimeter",
     "system": "si",
     "factor": 0.01,
     "exact": true
    },
    {
     "id": "meter",
     "slug": "meters",
     "symbol": "m",
     "name": "meter",
     "system": "si",
     "factor": 1,
     "exact": true
    },
    {
     "id": "kilometer",
     "slug": "kilometers",
     "symbol": "km",
     "name": "kilometer",
     "system": "si",
     "factor": 1000,
     "exact": true
    },
    {
     "id": "micrometer",
     "slug": "micrometers",
     "symbol": "µm",
     "name": "micrometer",
     "system": "si",
     "factor": 0.000001,
     "exact": true
    },
    {
     "id": "inch",
     "slug": "inches",
     "symbol": "in",
     "name": "inch",
     "system": "impus",
     "factor": 0.0254,
     "exact": true
    },
    {
     "id": "foot",
     "slug": "feet",
     "symbol": "ft",
     "name": "foot",
     "system": "impus",
     "factor": 0.3048,
     "exact": true
    },
    {
     "id": "yard",
     "slug": "yards",
     "symbol": "yd",
     "name": "yard",
     "system": "impus",
     "factor": 0.9144,
     "exact": true
    },
    {
     "id": "mile",
     "slug": "miles",
     "symbol": "mi",
     "name": "mile",
     "system": "impus",
     "factor": 1609.344,
     "exact": true
    },
    {
     "id": "nautical-mile",
     "slug": "nautical-miles",
     "symbol": "nmi",
     "name": "nautical mile",
     "system": "other",
     "factor": 1852,
     "exact": true
    }
   ]
  },
  {
   "id": "mass",
   "base": "kilogram",
   "url": "https://calcora.dev/mass/",
   "units": [
    {
     "id": "milligram",
     "slug": "milligrams",
     "symbol": "mg",
     "name": "milligram",
     "system": "si",
     "factor": 0.000001,
     "exact": true
    },
    {
     "id": "gram",
     "slug": "grams",
     "symbol": "g",
     "name": "gram",
     "system": "si",
     "factor": 0.001,
     "exact": true
    },
    {
     "id": "kilogram",
     "slug": "kilograms",
     "symbol": "kg",
     "name": "kilogram",
     "system": "si",
     "factor": 1,
     "exact": true
    },
    {
     "id": "tonne",
     "slug": "metric-tons",
     "symbol": "t",
     "name": "metric ton",
     "system": "metric",
     "factor": 1000,
     "exact": true
    },
    {
     "id": "ounce",
     "slug": "ounces",
     "symbol": "oz",
     "name": "ounce",
     "system": "impus",
     "factor": 0.028349523125,
     "exact": true
    },
    {
     "id": "pound",
     "slug": "pounds",
     "symbol": "lb",
     "name": "pound",
     "system": "impus",
     "factor": 0.45359237,
     "exact": true
    },
    {
     "id": "stone",
     "slug": "stones",
     "symbol": "st",
     "name": "stone",
     "system": "imperial",
     "factor": 6.35029318,
     "exact": true
    },
    {
     "id": "short-ton",
     "slug": "us-tons",
     "symbol": "sh tn",
     "name": "US ton",
     "system": "us",
     "factor": 907.18474,
     "exact": true
    },
    {
     "id": "long-ton",
     "slug": "uk-tons",
     "symbol": "LT",
     "name": "UK ton",
     "system": "imperial",
     "factor": 1016.0469088,
     "exact": true
    },
    {
     "id": "carat",
     "slug": "carats",
     "symbol": "ct",
     "name": "carat",
     "system": "metric",
     "factor": 0.0002,
     "exact": true
    }
   ]
  },
  {
   "id": "temperature",
   "base": "kelvin",
   "url": "https://calcora.dev/temperature/",
   "units": [
    {
     "id": "celsius",
     "slug": "celsius",
     "symbol": "°C",
     "name": "degree Celsius",
     "system": "si",
     "affine": [
      1,
      273.15
     ],
     "exact": true
    },
    {
     "id": "fahrenheit",
     "slug": "fahrenheit",
     "symbol": "°F",
     "name": "degree Fahrenheit",
     "system": "us",
     "affine": [
      0.5555555555555556,
      255.3722222222222
     ],
     "exact": true
    },
    {
     "id": "kelvin",
     "slug": "kelvin",
     "symbol": "K",
     "name": "kelvin",
     "system": "si",
     "affine": [
      1,
      0
     ],
     "exact": true
    }
   ]
  },
  {
   "id": "volume",
   "base": "liter",
   "url": "https://calcora.dev/volume/",
   "units": [
    {
     "id": "milliliter",
     "slug": "milliliters",
     "symbol": "mL",
     "name": "milliliter",
     "system": "metric",
     "factor": 0.001,
     "exact": true
    },
    {
     "id": "liter",
     "slug": "liters",
     "symbol": "L",
     "name": "liter",
     "system": "metric",
     "factor": 1,
     "exact": true
    },
    {
     "id": "cubic-meter",
     "slug": "cubic-meters",
     "symbol": "m³",
     "name": "cubic meter",
     "system": "si",
     "factor": 1000,
     "exact": true
    },
    {
     "id": "teaspoon",
     "slug": "teaspoons",
     "symbol": "tsp",
     "name": "US teaspoon",
     "system": "us",
     "factor": 0.00492892159375,
     "exact": true
    },
    {
     "id": "tablespoon",
     "slug": "tablespoons",
     "symbol": "tbsp",
     "name": "US tablespoon",
     "system": "us",
     "factor": 0.01478676478125,
     "exact": true
    },
    {
     "id": "fluid-ounce",
     "slug": "fluid-ounces",
     "symbol": "fl oz",
     "name": "US fluid ounce",
     "system": "us",
     "factor": 0.0295735295625,
     "exact": true
    },
    {
     "id": "cup",
     "slug": "cups",
     "symbol": "cup",
     "name": "US cup",
     "system": "us",
     "factor": 0.2365882365,
     "exact": true
    },
    {
     "id": "pint",
     "slug": "pints",
     "symbol": "pt",
     "name": "US pint",
     "system": "us",
     "factor": 0.473176473,
     "exact": true
    },
    {
     "id": "quart",
     "slug": "quarts",
     "symbol": "qt",
     "name": "US quart",
     "system": "us",
     "factor": 0.946352946,
     "exact": true
    },
    {
     "id": "gallon",
     "slug": "gallons",
     "symbol": "gal",
     "name": "US gallon",
     "system": "us",
     "factor": 3.785411784,
     "exact": true
    },
    {
     "id": "imperial-gallon",
     "slug": "imperial-gallons",
     "symbol": "imp gal",
     "name": "imperial gallon",
     "system": "imperial",
     "factor": 4.54609,
     "exact": true
    },
    {
     "id": "cubic-foot",
     "slug": "cubic-feet",
     "symbol": "ft³",
     "name": "cubic foot",
     "system": "impus",
     "factor": 28.316846592,
     "exact": true
    },
    {
     "id": "cubic-inch",
     "slug": "cubic-inches",
     "symbol": "in³",
     "name": "cubic inch",
     "system": "impus",
     "factor": 0.016387064,
     "exact": true
    }
   ]
  },
  {
   "id": "area",
   "base": "square-meter",
   "url": "https://calcora.dev/area/",
   "units": [
    {
     "id": "square-centimeter",
     "slug": "square-centimeters",
     "symbol": "cm²",
     "name": "square centimeter",
     "system": "si",
     "factor": 0.0001,
     "exact": true
    },
    {
     "id": "square-meter",
     "slug": "square-meters",
     "symbol": "m²",
     "name": "square meter",
     "system": "si",
     "factor": 1,
     "exact": true
    },
    {
     "id": "square-kilometer",
     "slug": "square-kilometers",
     "symbol": "km²",
     "name": "square kilometer",
     "system": "si",
     "factor": 1000000,
     "exact": true
    },
    {
     "id": "hectare",
     "slug": "hectares",
     "symbol": "ha",
     "name": "hectare",
     "system": "metric",
     "factor": 10000,
     "exact": true
    },
    {
     "id": "acre",
     "slug": "acres",
     "symbol": "ac",
     "name": "acre",
     "system": "impus",
     "factor": 4046.8564224,
     "exact": true
    },
    {
     "id": "square-inch",
     "slug": "square-inches",
     "symbol": "in²",
     "name": "square inch",
     "system": "impus",
     "factor": 0.00064516,
     "exact": true
    },
    {
     "id": "square-foot",
     "slug": "square-feet",
     "symbol": "ft²",
     "name": "square foot",
     "system": "impus",
     "factor": 0.09290304,
     "exact": true
    },
    {
     "id": "square-yard",
     "slug": "square-yards",
     "symbol": "yd²",
     "name": "square yard",
     "system": "impus",
     "factor": 0.83612736,
     "exact": true
    },
    {
     "id": "square-mile",
     "slug": "square-miles",
     "symbol": "mi²",
     "name": "square mile",
     "system": "impus",
     "factor": 2589988.110336,
     "exact": true
    }
   ]
  },
  {
   "id": "speed",
   "base": "meter-per-second",
   "url": "https://calcora.dev/speed/",
   "units": [
    {
     "id": "meter-per-second",
     "slug": "meters-per-second",
     "symbol": "m/s",
     "name": "meter per second",
     "system": "si",
     "factor": 1,
     "exact": true
    },
    {
     "id": "kilometer-per-hour",
     "slug": "km-per-hour",
     "symbol": "km/h",
     "name": "kilometer per hour",
     "system": "metric",
     "factor": 0.2777777777777778,
     "exact": true
    },
    {
     "id": "mile-per-hour",
     "slug": "mph",
     "symbol": "mph",
     "name": "mile per hour",
     "system": "impus",
     "factor": 0.44704,
     "exact": true
    },
    {
     "id": "knot",
     "slug": "knots",
     "symbol": "kn",
     "name": "knot",
     "system": "other",
     "factor": 0.5144444444444445,
     "exact": true
    },
    {
     "id": "foot-per-second",
     "slug": "feet-per-second",
     "symbol": "ft/s",
     "name": "foot per second",
     "system": "impus",
     "factor": 0.3048,
     "exact": true
    }
   ]
  },
  {
   "id": "duration",
   "base": "second",
   "url": "https://calcora.dev/duration/",
   "units": [
    {
     "id": "millisecond",
     "slug": "milliseconds",
     "symbol": "ms",
     "name": "millisecond",
     "system": "si",
     "factor": 0.001,
     "exact": true
    },
    {
     "id": "second",
     "slug": "seconds",
     "symbol": "s",
     "name": "second",
     "system": "si",
     "factor": 1,
     "exact": true
    },
    {
     "id": "minute",
     "slug": "minutes",
     "symbol": "min",
     "name": "minute",
     "system": "metric",
     "factor": 60,
     "exact": true
    },
    {
     "id": "hour",
     "slug": "hours",
     "symbol": "h",
     "name": "hour",
     "system": "metric",
     "factor": 3600,
     "exact": true
    },
    {
     "id": "day",
     "slug": "days",
     "symbol": "d",
     "name": "day",
     "system": "metric",
     "factor": 86400,
     "exact": true
    },
    {
     "id": "week",
     "slug": "weeks",
     "symbol": "wk",
     "name": "week",
     "system": "other",
     "factor": 604800,
     "exact": true
    },
    {
     "id": "month",
     "slug": "months",
     "symbol": "mo",
     "name": "month",
     "system": "other",
     "factor": 2629746,
     "exact": false
    },
    {
     "id": "year",
     "slug": "years",
     "symbol": "yr",
     "name": "year",
     "system": "other",
     "factor": 31556952,
     "exact": false
    }
   ]
  },
  {
   "id": "data",
   "base": "byte",
   "url": "https://calcora.dev/data/",
   "units": [
    {
     "id": "bit",
     "slug": "bits",
     "symbol": "bit",
     "name": "bit",
     "system": "other",
     "factor": 0.125,
     "exact": true
    },
    {
     "id": "byte",
     "slug": "bytes",
     "symbol": "B",
     "name": "byte",
     "system": "other",
     "factor": 1,
     "exact": true
    },
    {
     "id": "kilobyte",
     "slug": "kilobytes",
     "symbol": "kB",
     "name": "kilobyte",
     "system": "si",
     "factor": 1000,
     "exact": true
    },
    {
     "id": "megabyte",
     "slug": "megabytes",
     "symbol": "MB",
     "name": "megabyte",
     "system": "si",
     "factor": 1000000,
     "exact": true
    },
    {
     "id": "gigabyte",
     "slug": "gigabytes",
     "symbol": "GB",
     "name": "gigabyte",
     "system": "si",
     "factor": 1000000000,
     "exact": true
    },
    {
     "id": "terabyte",
     "slug": "terabytes",
     "symbol": "TB",
     "name": "terabyte",
     "system": "si",
     "factor": 1000000000000,
     "exact": true
    },
    {
     "id": "petabyte",
     "slug": "petabytes",
     "symbol": "PB",
     "name": "petabyte",
     "system": "si",
     "factor": 1000000000000000,
     "exact": true
    },
    {
     "id": "kibibyte",
     "slug": "kibibytes",
     "symbol": "KiB",
     "name": "kibibyte",
     "system": "iec",
     "factor": 1024,
     "exact": true
    },
    {
     "id": "mebibyte",
     "slug": "mebibytes",
     "symbol": "MiB",
     "name": "mebibyte",
     "system": "iec",
     "factor": 1048576,
     "exact": true
    },
    {
     "id": "gibibyte",
     "slug": "gibibytes",
     "symbol": "GiB",
     "name": "gibibyte",
     "system": "iec",
     "factor": 1073741824,
     "exact": true
    },
    {
     "id": "tebibyte",
     "slug": "tebibytes",
     "symbol": "TiB",
     "name": "tebibyte",
     "system": "iec",
     "factor": 1099511627776,
     "exact": true
    }
   ]
  },
  {
   "id": "energy",
   "base": "joule",
   "url": "https://calcora.dev/energy/",
   "units": [
    {
     "id": "joule",
     "slug": "joules",
     "symbol": "J",
     "name": "joule",
     "system": "si",
     "factor": 1,
     "exact": true
    },
    {
     "id": "kilojoule",
     "slug": "kilojoules",
     "symbol": "kJ",
     "name": "kilojoule",
     "system": "si",
     "factor": 1000,
     "exact": true
    },
    {
     "id": "calorie",
     "slug": "calories",
     "symbol": "cal",
     "name": "calorie",
     "system": "other",
     "factor": 4.184,
     "exact": true
    },
    {
     "id": "kilocalorie",
     "slug": "kilocalories",
     "symbol": "kcal",
     "name": "kilocalorie",
     "system": "other",
     "factor": 4184,
     "exact": true
    },
    {
     "id": "watt-hour",
     "slug": "watt-hours",
     "symbol": "Wh",
     "name": "watt-hour",
     "system": "metric",
     "factor": 3600,
     "exact": true
    },
    {
     "id": "kilowatt-hour",
     "slug": "kilowatt-hours",
     "symbol": "kWh",
     "name": "kilowatt-hour",
     "system": "metric",
     "factor": 3600000,
     "exact": true
    },
    {
     "id": "btu",
     "slug": "btu",
     "symbol": "BTU",
     "name": "BTU",
     "system": "impus",
     "factor": 1055.05585262,
     "exact": true
    },
    {
     "id": "electronvolt",
     "slug": "electronvolts",
     "symbol": "eV",
     "name": "electronvolt",
     "system": "other",
     "factor": 1.602176634e-19,
     "exact": true
    }
   ]
  },
  {
   "id": "pressure",
   "base": "pascal",
   "url": "https://calcora.dev/pressure/",
   "units": [
    {
     "id": "pascal",
     "slug": "pascals",
     "symbol": "Pa",
     "name": "pascal",
     "system": "si",
     "factor": 1,
     "exact": true
    },
    {
     "id": "hectopascal",
     "slug": "hectopascals",
     "symbol": "hPa",
     "name": "hectopascal",
     "system": "si",
     "factor": 100,
     "exact": true
    },
    {
     "id": "kilopascal",
     "slug": "kilopascals",
     "symbol": "kPa",
     "name": "kilopascal",
     "system": "si",
     "factor": 1000,
     "exact": true
    },
    {
     "id": "bar",
     "slug": "bar",
     "symbol": "bar",
     "name": "bar",
     "system": "metric",
     "factor": 100000,
     "exact": true
    },
    {
     "id": "psi",
     "slug": "psi",
     "symbol": "psi",
     "name": "psi",
     "system": "impus",
     "factor": 6894.757293168,
     "exact": false
    },
    {
     "id": "atmosphere",
     "slug": "atmospheres",
     "symbol": "atm",
     "name": "standard atmosphere",
     "system": "other",
     "factor": 101325,
     "exact": true
    },
    {
     "id": "mmhg",
     "slug": "mmhg",
     "symbol": "mmHg",
     "name": "millimeter of mercury",
     "system": "other",
     "factor": 133.322387415,
     "exact": false
    }
   ]
  },
  {
   "id": "power",
   "base": "watt",
   "url": "https://calcora.dev/power/",
   "units": [
    {
     "id": "watt",
     "slug": "watts",
     "symbol": "W",
     "name": "watt",
     "system": "si",
     "factor": 1,
     "exact": true
    },
    {
     "id": "kilowatt",
     "slug": "kilowatts",
     "symbol": "kW",
     "name": "kilowatt",
     "system": "si",
     "factor": 1000,
     "exact": true
    },
    {
     "id": "horsepower",
     "slug": "horsepower",
     "symbol": "hp",
     "name": "horsepower",
     "system": "impus",
     "factor": 745.6998715822702,
     "exact": false
    },
    {
     "id": "metric-horsepower",
     "slug": "metric-horsepower",
     "symbol": "PS",
     "name": "metric horsepower",
     "system": "metric",
     "factor": 735.49875,
     "exact": true
    },
    {
     "id": "btu-per-hour",
     "slug": "btu-per-hour",
     "symbol": "BTU/h",
     "name": "BTU per hour",
     "system": "impus",
     "factor": 0.29307107017222,
     "exact": false
    }
   ]
  },
  {
   "id": "fuel",
   "base": "km-per-liter",
   "url": "https://calcora.dev/fuel/",
   "units": [
    {
     "id": "km-per-liter",
     "slug": "km-per-liter",
     "symbol": "km/L",
     "name": "kilometer per liter",
     "system": "metric",
     "factor": 1,
     "exact": true
    },
    {
     "id": "liter-per-100km",
     "slug": "liters-per-100km",
     "symbol": "L/100 km",
     "name": "liter per 100 km",
     "system": "metric",
     "reciprocal": 100,
     "exact": true
    },
    {
     "id": "mpg-us",
     "slug": "mpg-us",
     "symbol": "mpg US",
     "name": "mile per gallon (US)",
     "system": "us",
     "factor": 0.425143707430272,
     "exact": true
    },
    {
     "id": "mpg-uk",
     "slug": "mpg-uk",
     "symbol": "mpg UK",
     "name": "mile per gallon (UK)",
     "system": "imperial",
     "factor": 0.354006189934647,
     "exact": true
    }
   ]
  }
 ]
}