POST /v1/convert Requires API key

Single conversion via JSON body

Identical conversion behaviour to GET /v1/convert, using a JSON request body instead of query parameters. Both methods share the same conversion engine.

Prefer a language client when available: JavaScript / TypeScript, Python, or PHP (Laravel). Samples on this page stay raw HTTP so they match the OpenAPI contract.

Parameters

Name	Type	Required	Description
`value`	string	Yes	Measurement value as a decimal string
`from`	string	Yes	Source unit identifier
`to`	string	Yes	Target unit identifier
`decimals`	integer	No	Round the result to this many fractional decimal places (0-40, half-even). Omit for the full engine precision string.
`format_locale`	string	No	Language tag such as de-DE. Adds a formatted display string (for example 1,5 km) to the result next to the exact value. Requires the Developer plan or higher.

Possible errors

PLAN_REQUIRED · INVALID_VALUE · UNKNOWN_UNIT · AMBIGUOUS_UNIT · INCOMPATIBLE_UNITS · OUT_OF_RANGE · INVALID_REQUEST · UNSUPPORTED_MEDIA_TYPE · PAYLOAD_TOO_LARGE · UNAUTHORIZED · INVALID_API_KEY · RATE_LIMIT_EXCEEDED · QUOTA_EXCEEDED · SERVICE_UNAVAILABLE

All endpoints · Error reference

curl "https://api.unifyunits.com/v1/convert" \ -X POST \ -H "Authorization: Bearer $UNIFYUNITS_API_KEY" \ -H "Content-Type: application/json" \ -d '{ "value": "1", "from": "ft", "to": "m" }'