Unit Converter

Convert any number between units of measurement without an API key. Give a value and a source unit, and get the result in a single target unit or in every unit of the same category. Everything runs offline from exact conversion factors, so there is nothing to rate limit and nothing to break.

What it does

Send one or more conversion requests. For each one you provide a value and a from unit. Add a to unit to convert to that single unit. Leave to empty and the actor converts to every unit in the matching category. Units are auto-detected, so you never pick a category by hand.

Supported categories and a sample of their units:

• length: meter, kilometer, centimeter, millimeter, mile, yard, foot, inch, nautical mile
• weight and mass: kilogram, gram, milligram, metric ton, pound, ounce, stone, US ton, long ton
• temperature: Celsius, Fahrenheit, Kelvin, Rankine
• volume: liter, milliliter, cubic meter, US gallon, quart, pint, cup, fluid ounce, tablespoon, teaspoon, imperial gallon
• area: square meter, square kilometer, hectare, acre, square mile, square foot, square inch, square yard
• speed: meter per second, kilometer per hour, mile per hour, foot per second, knot
• time: second, millisecond, minute, hour, day, week, month, year
• digital storage: byte, bit, kilobyte, megabyte, gigabyte, terabyte, petabyte, plus binary kibibyte to tebibyte
• pressure: pascal, kilopascal, bar, psi, atmosphere, mmHg, torr
• energy: joule, kilojoule, calorie, kilocalorie, watt hour, kilowatt hour, BTU, foot pound
• power: watt, kilowatt, megawatt, horsepower, metric horsepower
• angle: degree, radian, gradian, arcminute, arcsecond, turn
• frequency: hertz, kilohertz, megahertz, gigahertz, rpm

Input

• conversions: a list of objects. Each needs value (a number) and from (a unit). Optional to picks a single target unit; omit it to get the whole category.
• precision: decimal places to round to, 0 to 15. Default 6.

Units accept short symbols or full names. km, kilometer, kilometre, and kilometers all resolve to the same unit. Temperature accepts C, F, K, celsius, fahrenheit, and similar.

Example input:

{
  "conversions": [
    { "value": 100, "from": "km", "to": "mi" },
    { "value": 72, "from": "F" },
    { "value": 5, "from": "kg", "to": "lb" },
    { "value": 1, "from": "GB", "to": "MB" }
  ],
  "precision": 6
}

Output

One row per target unit. Each row has:

• inputValue: the value you sent
• fromUnit, fromUnitName: source unit symbol and full name
• category: the detected category, for example length or temperature
• toUnit, toUnitName: target unit symbol and full name
• result: the converted number, rounded to your precision
• formatted: a ready-to-read string like 100 km = 62.137119 mi
• error: null on success, or a short message for an unknown unit or a cross-category request

Results export to JSON, CSV, or Excel from the dataset.

Why it stays reliable

There is no third-party API, no key, and no login. Conversions come from fixed, standardized factors held in the code, so the same input always gives the same answer.