The Units Converter API allows developers to easily add a units converter to their applications. This is done by performing HTTP GET requests with the appropriate parameters. An API key is needed to make API calls. The units converter API returns JSON formatted data. If the call were successful, it would return a status of 200, else, it would return a status of 400.
The following API call returns an array of all the measurements for which the API provides conversion:

API call:
https://units-converter.p.rapidapi.com/dev/measurements

Description:
Returns an array of all the measurements for which the API provides conversion:
Returns:
{
“measurements”: [
“acceleration”,
“angle”,
“area”,
“data”,
“density”,
“energy”,
“force”,
“fuelEconomy”,
“illuminance”,
“length”,
“luminance”,
“mass”,
“massFlow”,
“power”,
“pressure”,
“speed”,
“temperature”,
“time”,
“torque”,
“volume”,
“volumeFlow”
]
}

API call:
GET: https://units-converter.p.rapidapi.com/dev//allUnits
Description:
Returns all the units of a measurement that the API provides conversion between.
Example:
Get all the units of angle that the API provides conversion between.
API call: GET: https://units-converter.p.rapidapi.com/dev/angle/allUnits
Returns:
[
“binary-degrees”,
“clock-positions”,
“compass-points”,
“degrees”,
“diameter-parts”,
“gradians”,
“hexacontades”,
“hour-angles”,
“mils-nato”,
“mils-soviet-union”,
“mils-sweden”,
“minutes”,
“octants”,
“pechus”,
“quadrants”,
“radians”,
“seconds”,
“sectants”,
“sign”,
“turns”
]

API call:
GET: https://units-converter.p.rapidapi.com/dev//?convert=&from=&to=
Description:
Converts the given quantity of unit1 to the equivalent quantity in unit2, for a given measurement, and returns the answer.
Example:
Convert 3 btu-mean of energy to its equivalent in kilowatt-hour.
API call:
GET: https://units-converter.p.rapidapi.com/dev/energy/?convert=3&from=btu-mean&to=kilowatt-hour
Returns:
{
“convert”: “3”,
“from”: “btu-mean”,
“to”: “kilowatt-hour”,
“equal”: 0.0008798916666666666,
“status”: 200,
“measurement”: “energy”
}
Answer:
3 BTU mean equals 0.0008798916666666666 KWh

API call:
GET: https://units-converter.p.rapidapi.com/dev///convertall/?convert=&from=unit
Description:
Converts the given quantity of a unit to the equivalent amount of all other units of a given measurement that the API provides conversion between.
Example:
Convert 8 barns to the equivalent amount of all of the other length units.
API call: GET: https://units-converter.p.rapidapi.com/dev/area/convertall/?convert=8&from=barn
Returns:
{
“convert”: “8”,
“from”: “barn”,
“acres-international”: 1.9768430517373224e-31,
“acres-us-survey”: 1.9768349538026027e-31,
“ares”: 7.999999999999999e-30,
“barn”: 8,
“barony”: 4.942109366409224e-35,
“board”: 1.0333354000041333e-25,
“boiler-horsepower”: 6.173709351332988e-29,
“centares”: 8e-28,
“circular-inches”: 1.5788201279831068e-24,
“circular-mils”: 1.5788201279831064e-18,
“cords”: 5.381955208354861e-28,
“cuerda-pr-survey”: 2.0354185082831198e-31,
“darcy”: 8.105999726625158e-16,
“duanams”: 7.999999999999999e-31,
“guntha”: 7.907482455273301e-30,
“hectares”: 7.999999999999999e-32,
“hides”: 1.6e-33,
“homesteads”: 1.2355212355212355e-33,
“roods”: 7.90737220694929e-31,
“sections”: 3.0888172683395668e-34,
“sheds”: 8e+24,
“squares-roofing”: 8.611128333367777e-29,
“sq-centimeters”: 8e-24,
“sq-chains - international”: 1.976843051737323e-30,
“sq-chains-us-survey”: 1.9768349538026027e-30,
“sq-decimeters”: 7.999999999999999e-26,
“sq-foot”: 8.611128333367777e-27,
“sq-foot-us-survey”: 8.611093888888874e-27,
“sq-inches”: 1.24000248000496e-24,
“sq-kilometers”: 8e-34,
“sq-links-gunters-international”: 1.9768430517373228e-26,
“sq-links-gunters-us-survey”: 1.9768354422872775e-26,
“sq-links-ramsden”: 8.611128333367777e-27,
“sq-meters”: 8e-28,
“sq-mils”: 1.24000248000496e-18,
“sq-miles”: 3.0888172683395668e-34,
“sq-miles-us-survey”: 3.0888049134639062e-34,
“sq-millimeters”: 8e-22,
“sq-rods”: 3.1629488827797165e-29,
“sq-yards”: 9.567920370408643e-28,
“stremma”: 7.999999999999999e-31,
“townships”: 8.580014101253175e-36,
“yardlands”: 6.666666666666667e-33,
“status”: 200,
“measurement”: “area”
}