Unit conversion

What this does

Converts a numeric value from one unit to another. Supports everyday pairs such as miles to kilometres, pounds to kilograms, Celsius to Fahrenheit, and litres to pints. You send what you have; the API returns the equivalent.

Who it is for

• Product specs crossing metric and imperial
• Recipe and brewing calculators
• Fitness apps (stones to kg)
• School homework and quick sanity checks

Try it

10 miles to kilometres:

https://fetch.li/v1/convert?from=mi&to=km&value=10

Other examples:

https://fetch.li/v1/convert?from=c&to=f&value=20
https://fetch.li/v1/convert?from=lb&to=kg&value=150
https://fetch.li/v1/convert?from=l&to=pt&value=2

HTTP example

GET /v1/convert?from=mi&to=km&value=10 HTTP/1.1
Host: fetch.li
Accept: application/json

curl

curl -sS "https://fetch.li/v1/convert?from=mi&to=km&value=10"

JavaScript fetch

const params = new URLSearchParams({ from: "mi", to: "km", value: "10" });
const response = await fetch(`https://fetch.li/v1/convert?${params}`);
const result = await response.json();
console.log(result.value, result.unit);

Python requests

import requests

response = requests.get(
    "https://fetch.li/v1/convert",
    params={"from": "mi", "to": "km", "value": 10},
)
response.raise_for_status()
print(response.json())

Example JSON response

{
  "from": "mi",
  "to": "km",
  "input": 10,
  "value": 16.0934,
  "unit": "km",
  "formula": "1 mi = 1.60934 km"
}

Parameters

Supported units are listed in the API catalog (GET /v1). Incompatible pairs return invalid_body.

Errors that can happen

Demo

GET endpoints work without an API key on the public demo tier (60 calls per hour per IP). POST /v1/vibe/classify needs a key.