> ## Documentation Index > Fetch the complete documentation index at: https://iotools.cloud/docs/llms.txt > Use this file to discover all available pages before exploring further. # Unit Converter > Convert between units of length, mass/weight, temperature, volume, area, speed, data storage, and pressure. Pick a category, choose the units, and get an instant result — or switch on 'Show all units' to see every unit in that category at once. [Try Unit Converter in your browser →](https://iotools.cloud/tool/unit-converter/) ## OpenAPI ````yaml https://api.iotools.cloud/v1/openapi post /v1/tool/unit-converter openapi: 3.1.0 info: title: iotools.cloud API version: 1.0.0 description: >- Run any iotools.cloud tool over HTTP. Authenticate with `Authorization: Bearer iot_live_…`. **Only `POST /v1/tool/{slug}` costs credits.** Every GET here — the catalog, a tool's schema, your balance — is free. A tool call is charged its own weight or your plan's per-call minimum, whichever is larger; `x-iotools-credit-cost` on each operation is quoted at the free-tier minimum, and `GET /v1/tools/list` returns the exact figure for your key. `GET /v1/me/credits` reports what you have left, and `GET /v1/me/usage` reports what it went on. Failures are RFC 9457 problem documents — branch on `code`. servers: - url: https://api.iotools.cloud description: Production security: - bearerAuth: [] tags: - name: Catalog description: Find a tool and read its contract. Free. - name: Converters description: >- Convert between formats, encodings, and units — Base64, CSV and JSON, timestamps, and more. Fast, free, and processed right in your browser. - name: Formatters description: >- Format, beautify, minify, and validate code and data — JSON, HTML, CSS, SQL, and regex. Clean up messy input in one click, with nothing to upload. - name: Generators description: >- Generate exactly what you need and on demand — passwords, UUIDs, QR codes, hashes, random numbers, and more. Secure, instant, and free. - name: Calculators description: >- Crunch the numbers fast — from everyday math to specialized conversions and unit work. Free online calculators that run entirely in your browser. - name: Editors description: >- Edit and transform text, code, and images with quick, focused editors that run entirely in your browser — nothing to install, and no sign-up needed. - name: Utilities description: >- Everyday developer and web utilities — DNS and IP lookups, redirect and certificate checkers, and other quick diagnostics. Free and privacy-friendly. - name: Account description: Your key's allowance, limits and usage history. paths: /v1/tool/unit-converter: post: tags: - Converters summary: Unit Converter description: >- Convert between units of length, mass/weight, temperature, volume, area, speed, data storage, and pressure. Pick a category, choose the units, and get an instant result — or switch on 'Show all units' to see every unit in that category at once. [Try Unit Converter in your browser →](https://iotools.cloud/tool/unit-converter/) operationId: run_unit_converter requestBody: required: false content: application/json: schema: type: object properties: ioCategory: enum: - length - mass - temperature - volume - area - speed - data - pressure description: Category ioValue: type: number description: Amount ioLengthFrom: enum: - meter - kilometer - centimeter - millimeter - micrometer - nanometer - picometer - femtometer - decimeter - decameter - hectometer - mile - yard - foot - inch - nautical_mile - light_year - astronomical_unit - parsec - angstrom - fathom - chain - rod - league - furlong - mile_scandinavian - league_nautical - hand - cubit - pica - point - mil description: Convert from ioLengthTo: enum: - meter - kilometer - centimeter - millimeter - micrometer - nanometer - picometer - femtometer - decimeter - decameter - hectometer - mile - yard - foot - inch - nautical_mile - light_year - astronomical_unit - parsec - angstrom - fathom - chain - rod - league - furlong - mile_scandinavian - league_nautical - hand - cubit - pica - point - mil description: Convert to ioMassFrom: enum: - kilogram - gram - milligram - microgram - tonne - pound - ounce - stone - ton - metric_ton - carat - atomic_mass_unit - long_ton - short_hundredweight - long_hundredweight - pennyweight - grain description: Convert from ioMassTo: enum: - kilogram - gram - milligram - microgram - tonne - pound - ounce - stone - ton - metric_ton - carat - atomic_mass_unit - long_ton - short_hundredweight - long_hundredweight - pennyweight - grain description: Convert to ioTemperatureFrom: enum: - C - F - K - R - De - 'N' - Re - Ro - P description: Convert from ioTemperatureTo: enum: - C - F - K - R - De - 'N' - Re - Ro - P description: Convert to ioVolumeFrom: enum: - milliliter - liter - cubic_centimeter - cubic_meter - us_teaspoon - us_tablespoon - us_fluid_ounce - us_cup - us_pint - us_quart - us_gallon - imp_fluid_ounce - imp_pint - imp_gallon - cubic_inch - cubic_foot description: Convert from ioVolumeTo: enum: - milliliter - liter - cubic_centimeter - cubic_meter - us_teaspoon - us_tablespoon - us_fluid_ounce - us_cup - us_pint - us_quart - us_gallon - imp_fluid_ounce - imp_pint - imp_gallon - cubic_inch - cubic_foot description: Convert to ioAreaFrom: enum: - square_meter - square_kilometer - square_centimeter - square_millimeter - square_decimeter - square_dekameter - square_hectometer - hectare - acre - square_foot - square_yard - square_mile - square_inch - square_micrometer - square_nanometer description: Convert from ioAreaTo: enum: - square_meter - square_kilometer - square_centimeter - square_millimeter - square_decimeter - square_dekameter - square_hectometer - hectare - acre - square_foot - square_yard - square_mile - square_inch - square_micrometer - square_nanometer description: Convert to ioSpeedFrom: enum: - meter_per_second - kilometer_per_hour - mile_per_hour - foot_per_second - knot - kilometer_per_minute - centimeter_per_second - millimeter_per_second - mile_per_minute - inch_per_second - micrometer_per_second - nanometer_per_second description: Convert from ioSpeedTo: enum: - meter_per_second - kilometer_per_hour - mile_per_hour - foot_per_second - knot - kilometer_per_minute - centimeter_per_second - millimeter_per_second - mile_per_minute - inch_per_second - micrometer_per_second - nanometer_per_second description: Convert to ioDataFrom: enum: - bit - nibble - byte - kb - mb - gb - tb - pb - eb - kib - mib - gib - tib - pib - eib description: Convert from ioDataTo: enum: - bit - nibble - byte - kb - mb - gb - tb - pb - eb - kib - mib - gib - tib - pib - eib description: Convert to ioPressureFrom: enum: - pascal - kilopascal - megapascal - bar - millibar - atmosphere - tech_atmosphere - psi - ksi - torr - inhg - cmh2o description: Convert from ioPressureTo: enum: - pascal - kilopascal - megapascal - bar - millibar - atmosphere - tech_atmosphere - psi - ksi - torr - inhg - cmh2o description: Convert to ioShowAll: type: boolean description: Show all units ioPrecision: enum: - '0' - '2' - '4' - '6' - '8' - '10' description: Decimal precision required: [] responses: '200': description: Tool output content: application/json: schema: type: object required: - tool - tool_version - outputs - credits_used properties: request_id: type: string tool: type: string tool_version: type: string description: >- Output-contract version for this tool. Currently "1" for all tools. outputs: type: object properties: ioResult: type: string description: Result ioTable: type: string description: Converted to every unit credits_used: type: integer description: >- Credits this call consumed, after any settlement refund. 0 when metering is disabled. credits_remaining: type: - integer - 'null' description: >- Credits left in the current monthly allowance, or null when metering is disabled. '400': description: Invalid request. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' example: type: https://iotools.cloud/docs/errors/validation_error title: Invalid request status: 400 code: validation_error detail: One or more inputs are invalid — see `fields`. request_id: e4042b29-8f1e-4c7a-9b52-6f0d1a3c7e11 '401': description: Missing or invalid API key. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' example: type: https://iotools.cloud/docs/errors/invalid_api_key title: Invalid API key status: 401 code: invalid_api_key detail: 'Provide ''Authorization: Bearer ''.' request_id: e4042b29-8f1e-4c7a-9b52-6f0d1a3c7e11 '402': description: Monthly credit allowance exhausted. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' example: type: https://iotools.cloud/docs/errors/insufficient_credits title: Insufficient credits status: 402 code: insufficient_credits detail: >- This call costs 1 credit and 0 remain in this month's allowance. request_id: e4042b29-8f1e-4c7a-9b52-6f0d1a3c7e11 '403': description: Tool exists but has no API surface. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' example: type: https://iotools.cloud/docs/errors/tool_not_allowed title: Tool not available over the API status: 403 code: tool_not_allowed detail: >- "Background Remover" is available on iotools.cloud but has no API endpoint. request_id: e4042b29-8f1e-4c7a-9b52-6f0d1a3c7e11 '404': description: No such tool. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' example: type: https://iotools.cloud/docs/errors/tool_not_found title: Tool not found status: 404 code: tool_not_found detail: No tool with that slug. See GET /v1/tools. request_id: e4042b29-8f1e-4c7a-9b52-6f0d1a3c7e11 '413': description: Body too large. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' example: type: https://iotools.cloud/docs/errors/payload_too_large title: Payload too large status: 413 code: payload_too_large detail: Request body exceeds this tool's size limit. request_id: e4042b29-8f1e-4c7a-9b52-6f0d1a3c7e11 '429': description: Per-minute rate limit exceeded. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' example: type: https://iotools.cloud/docs/errors/rate_limited title: Rate limit exceeded status: 429 code: rate_limited detail: Too many requests. Retry in 30s. request_id: e4042b29-8f1e-4c7a-9b52-6f0d1a3c7e11 '500': description: Tool failed to run. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' example: type: https://iotools.cloud/docs/errors/processing_error title: Tool failed to run status: 500 code: processing_error detail: The tool failed to run. Please try again. request_id: e4042b29-8f1e-4c7a-9b52-6f0d1a3c7e11 '503': description: Tool temporarily disabled. content: application/problem+json: schema: $ref: '#/components/schemas/Problem' example: type: https://iotools.cloud/docs/errors/tool_disabled title: Tool temporarily disabled status: 503 code: tool_disabled detail: This tool is temporarily unavailable. Try again shortly. request_id: e4042b29-8f1e-4c7a-9b52-6f0d1a3c7e11 security: - bearerAuth: [] components: schemas: Problem: type: object description: >- RFC 9457 problem document, served as application/problem+json. Branch on `code`; `title` is human prose and may be reworded without notice. required: - type - title - status - code properties: type: type: string format: uri description: Stable documentation URI for this failure. examples: - https://iotools.cloud/docs/errors/invalid_api_key - https://iotools.cloud/docs/errors/api_unconfigured - https://iotools.cloud/docs/errors/validation_error - https://iotools.cloud/docs/errors/payload_too_large - https://iotools.cloud/docs/errors/tool_not_found - https://iotools.cloud/docs/errors/tool_not_allowed - https://iotools.cloud/docs/errors/tool_disabled - https://iotools.cloud/docs/errors/rate_limited - https://iotools.cloud/docs/errors/insufficient_credits - https://iotools.cloud/docs/errors/processing_error - https://iotools.cloud/docs/errors/internal_error title: type: string examples: - Invalid API key - API not configured - Invalid request - Payload too large - Tool not found - Tool not available over the API - Tool temporarily disabled - Rate limit exceeded - Insufficient credits - Tool failed to run - Internal error status: type: integer code: type: string enum: - invalid_api_key - api_unconfigured - validation_error - payload_too_large - tool_not_found - tool_not_allowed - tool_disabled - rate_limited - insufficient_credits - processing_error - internal_error detail: type: string description: Human explanation of this occurrence. request_id: type: string description: Correlation id, also sent as x-request-id. securitySchemes: bearerAuth: type: http scheme: bearer bearerFormat: iot_live_… ````