# SiteCheck Unit Converter

> 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 2026-10-20).

Converts a numeric value from one measurement unit to another (length, mass, temperature, digital storage, energy, volume, etc.) using NIST-standard conversion factors.

## Facts

- Endpoint: GET https://api.sitecheck-api.workers.dev/api/units?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-20
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/sitecheck-unit-converter-66a3afcd
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_AhbUwyxmLtnCs3t6EW4nR

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability sitecheck-unit-converter-66a3afcd
```

Example prompt: Convert 26.2 miles to kilometers for me.

## When to prefer this

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.

## Known failure modes

- 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

## 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.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "value",
      "from",
      "to"
     ],
     "properties": {
      "to": {
       "type": "string",
       "description": "Unit to convert to, of the same kind, e.g. km, lb, C, MB"
      },
      "from": {
       "type": "string",
       "description": "Unit to convert from, e.g. mi, kg, F, GiB, kWh, gal_us"
      },
      "value": {
       "type": "string",
       "description": "The number to convert, up to 1e15 in size"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "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"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/sitecheck-unit-converter-66a3afcd/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.sitecheck-api.workers.dev](https://www.zero.xyz/host/api.sitecheck-api.workers.dev/llms.txt)