Unit Converter API

Documentation

Base URL

https://convert.freeapi.me/

All API requests should be made to this endpoint. HTTPS is required for all API calls.

Endpoints

Parameters for /convert

The following query parameters can be used with the /convert endpoint:

Example Requests

# Convert 10 kilometers to miles
curl "https://convert.freeapi.me/convert?value=10&from=km&to=miles"

# Convert 100 Celsius to Fahrenheit, rounded to 1 decimal place
curl "https://convert.freeapi.me/convert?value=100&from=c&to=f&round=1"

# Convert 1.5 GB to MB
curl "https://convert.freeapi.me/convert?value=1.5&from=GB&to=MB"

// Convert 10 kilometers to miles
fetch('https://convert.freeapi.me/convert?value=10&from=km&to=miles')
  .then(response => response.json())
  .then(data => console.log(data))
  .catch(error => console.error('Error:', error));

// Convert with rounding
fetch('https://convert.freeapi.me/convert?value=100&from=c&to=f&round=1')
  .then(response => response.json())
  .then(data => console.log(data))
  .catch(error => console.error('Error:', error));

import requests

# Convert 10 kilometers to miles
response = requests.get('https://convert.freeapi.me/convert',
                        params={'value': 10, 'from': 'km', 'to': 'miles'})
data = response.json()
print(data)

# Convert with rounding
response = requests.get('https://convert.freeapi.me/convert',
                        params={'value': 100, 'from': 'c', 'to': 'f', 'round': 1})
data = response.json()
print(data)

// Convert 10 kilometers to miles
$url = 'https://convert.freeapi.me/convert?value=10&from=km&to=miles';
$response = file_get_contents($url);
$data = json_decode($response, true);
print_r($data);

// Convert with rounding
$url = 'https://convert.freeapi.me/convert?value=100&from=c&to=f&round=1';
$response = file_get_contents($url);
$data = json_decode($response, true);
print_r($data);

Response Format

The API returns a JSON object with details about the conversion:

{
  "originalValue": 10,         // The input value provided
  "fromUnit": "km",            // The source unit (canonical form)
  "convertedValue": 6.21371,   // The converted result
  "toUnit": "miles",           // The target unit (canonical form)
  "roundingPlaces": 2          // Only included if rounding was applied
}

Error Responses

The API may return the following error responses:

• 400 Bad Request - Returned if parameters are missing or invalid
• 404 Not Found - Returned for undefined endpoints
• 405 Method Not Allowed - Returned if using a method other than GET

Error response format:

{
  "error": "Detailed error message explaining what went wrong"
}

Supported Unit Categories

The API supports conversion between units within the following categories. Units can only be converted within the same category.

Unit Aliases

The API supports various aliases for the same unit. For example, you can use "km", "kilometer", or "kilometers" interchangeably. For a complete list of supported units and their aliases, you can make a request to the /help endpoint.

GET https://convert.freeapi.me/help