Unit Converter API

Convert length, mass, temperature, volume, area, speed, data, time, pressure, and energy.

Unit Converter handles conversions across ten categories — length, mass, temperature, volume, area, speed, data size, time, pressure, and energy — through one simple GET endpoint. Pass a value, a from unit, and a to unit (short codes like km, mi, kg, lb, c, f); the category is inferred automatically, or you can set it explicitly.

It also lists every category and the units within it, so you can build dropdowns and validation dynamically. Pure math, stateless, and instant — no data is stored. Great for calculators, e-commerce, fitness and recipe apps, engineering tools, and dashboards.

Step-by-step tutorial: Unit Conversion API: Length, Mass, Temperature, and 7 More Categories

Endpoints

Quick start

curl --request curl \
  --url 'https://unit-converter26.p.rapidapi.com/-G "https://unit-converter26.p.rapidapi.com/convert" -d "value=100" -d "from=km" -d "to=mi" -H "X-RapidAPI-Key: YOUR_KEY" -H "X-RapidAPI-Host: unit-converter26.p.rapidapi.com"' \
  --header 'X-RapidAPI-Key: YOUR_KEY' \
  --header 'X-RapidAPI-Host: unit-converter26.p.rapidapi.com' \
  --header 'content-type: application/json' \
  --data '{}'

const res = await fetch('https://unit-converter26.p.rapidapi.com/-G "https://unit-converter26.p.rapidapi.com/convert" -d "value=100" -d "from=km" -d "to=mi" -H "X-RapidAPI-Key: YOUR_KEY" -H "X-RapidAPI-Host: unit-converter26.p.rapidapi.com"', {
  method: 'curl',
  headers: {
    'X-RapidAPI-Key': 'YOUR_KEY',
    'X-RapidAPI-Host': 'unit-converter26.p.rapidapi.com',
    'content-type': 'application/json'
  },
  body: JSON.stringify({})
});
const data = await res.json();

{
  "value": 100,
  "from": "km",
  "to": "mi",
  "category": "length",
  "result": 62.1371
}

Pricing

Subscribe on RapidAPI. Start free; upgrade as you scale.

For AI agents

Programmatic discovery and keyless testing:

• OpenAPI spec: https://abundanceapis.com/openapi/unit-converter26.json
• MCP server (keyless trial): https://abundanceapis.com/mcp — add this Streamable-HTTP MCP endpoint in Claude, Cursor, or any MCP client, then call list_apis and the sample tools.
• Production: subscribe on RapidAPI and send X-RapidAPI-Key + X-RapidAPI-Host: unit-converter26.p.rapidapi.com.