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SiteCheck Unit Converter
x402
SiteCheck Unit Converter is a paid API for AI agents from api.sitecheck-api.workers.dev, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-16).
Converts a numeric value from one measurement unit to another (length, mass, temperature, digital storage, energy, volume, etc.) using NIST-standard conversion factors.
Price / call$0.001
Success—
StatusUnknown
How this service works
Convert a value between units of length, area, volume (US customary and metric, cooking measures), mass, speed, pressure, energy, power, data size (SI and binary), time and temperature. Factors are exact to the definitions in NIST SP 811 (international inch and pound, US gallon, calorie IT, Btu IT, mechanical horsepower). An unknown unit is a 400 that lists every supported unit. Pure code, no outside source.
Output
A JSON object containing the converted numeric result, the source unit, the target unit, the unit family (e.g. length, mass, temperature), the authoritative source of the conversion factor (NIST SP 811), and the timestamp of the calculation.
Example use cases
Marathon distance in metric
“How many kilometers is 26.2 miles? I need the exact figure for a race results report.”
Oven temperature unit conversion
“My recipe calls for 375 degrees Fahrenheit — what is that in Celsius?”
Cloud storage size normalization
“Convert 512 GiB to megabytes so I can compare it consistently with the other storage figures in my spreadsheet.”
Technical details
Endpoint
GEThttps://api.sitecheck-api.workers.dev/api/units?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a reliable, citation-backed unit conversion (NIST SP 811) across a wide variety of physical and digital unit families without setting up a local conversion library. Particularly useful in agent workflows where measurements arrive in mixed units and need to be normalized on the fly, or when auditability of the conversion source matters. At $0.001 per call it is cost-effective for occasional conversions in automated pipelines.
Side effects
- Missing required query parameter (value, from, or to) returns a validation error
- Incompatible unit families (e.g. converting miles to kilograms) returns an error indicating units are not of the same kind
- Unsupported or misspelled unit abbreviation returns an error
- Value exceeding 1e15 may be rejected or produce inaccurate results
- Payment not completed (x402 payment required) returns a 402 response before conversion is performed
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"to": "km",
"from": "mi",
"value": 5,
"family": "length",
"result": 8.04672,
"source": "NIST SP 811 (Guide for the Use of the International System of Units), factors to the SI base unit",
"checkedAt": "2026-10-15T14:00:29.549Z"
}
}Tags
x402
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