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fastapi.online Unit Converter
x402
fastapi.online Unit Converter is a paid API for AI agents from api.fastapi.online, paid per call via x402, $0.0005/call, status unknown (last checked 2026-09-14).
Converts a numeric value from one unit of measurement to another unit via a simple POST call, priced per call with crypto.
Price / call$0.0005
Success—
StatusUnknown
How this service works
Chat, embeddings, OCR, speech-to-text, image editing, image understanding (captioning/Q&A), text-to-speech, translation, writing tools, classification tools, developer tools, local utilities, format/checksum validators, encoding & crypto utilities, date/time calculators, geo/coordinate math, math & finance calculators, novelty tools, and business/social writing generators — 179 endpoints in all, across multiple specialized self-hosted models. Pay per call with crypto — no signup — or get an API key.
Output
Returns the numeric result of converting the given value from the source unit to the target unit. The response includes the converted value in the requested target unit.
Example use cases
Recipe ingredient unit conversion
“I have a recipe that calls for 2.5 cups of flour but I only have a kitchen scale — can you convert 2.5 cups to grams for me?”
Travel distance calculation
“I'm planning a road trip and the map shows 320 kilometers — how many miles is that?”
Body weight unit conversion
“My doctor recorded my weight as 185 pounds but I need it in kilograms for this European health form — can you convert that?”
Technical details
Endpoint
POSThttps://api.fastapi.online/unit-convertWhen to prefer
Choose this endpoint when you need a quick, programmatic unit conversion without requiring a full math library or external conversion service integration. It is ideal for AI agents that need to convert single values on-the-fly within a pay-per-call crypto-payment workflow (x402 protocol), and when no signup or API key setup is desired.
Side effects
- Unsupported or unrecognized unit strings in 'from' or 'to' fields may return an error or null result
- Invalid or missing 'value' field (non-numeric) causes a 400 validation error
- Units from incompatible dimensions (e.g. converting kg to meters) may return an error
- Payment failure or insufficient USDC balance returns a 402 Payment Required response
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| to | string | |
| from | string | |
| value | number |
Tags
x402
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