{ "id": "unit-converter", "version": "31ed7e204ead", "status": "published", "name": "Unit Converter", "question": "How do I convert a measurement?", "summary": "Converts a measurement of length, weight, volume, temperature, area, or speed from any unit to any other.", "category": "convert", "subcategory": "units", "url": "https://www.acalculator.org/convert/unit", "markdown": "https://www.acalculator.org/convert/unit.md", "kind": "function", "method": "converted = amount × (base units per \"From\" unit) ÷ (base units per \"To\" unit); temperatures add an offset", "assumptions": [ "Every factor is the exact definition in NIST SP 811 (2008), Appendix B.8: 1 in = 2.54 cm, 1 lb = 0.45359237 kg, 1 US gallon = 231 in³.", "Cups, pints, quarts, gallons, and fluid ounces are US customary units.", "Temperatures convert through kelvins: K = °C + 273.15 = (°F + 459.67) × 5 ÷ 9. Nothing is colder than 0 K.", "A length, weight, volume, area, or speed cannot be negative.", "The answer shows at most 6 decimal places; the calculation keeps full precision." ], "inputs": { "$schema": "https://json-schema.org/draft/2020-12/schema", "type": "object", "properties": { "measure": { "title": "Measure", "description": "What kind of measurement to convert.", "type": "string", "enum": [ "length", "weight", "volume", "temperature", "area", "speed" ] }, "amount": { "title": "Amount", "description": "The measurement to convert, in the \"From\" unit.", "type": "number", "minimum": -1000000000000, "maximum": 1000000000000 }, "lengthFrom": { "title": "From", "description": "The unit of length the amount is in.", "type": "string", "enum": [ "mm", "cm", "m", "km", "um", "nm", "in", "ft", "yd", "mi", "nmi", "mil" ] }, "lengthTo": { "title": "To", "description": "The unit of length to convert to.", "type": "string", "enum": [ "mm", "cm", "m", "km", "um", "nm", "in", "ft", "yd", "mi", "nmi", "mil" ] }, "weightFrom": { "title": "From", "description": "The unit of weight the amount is in.", "type": "string", "enum": [ "ug", "mg", "g", "kg", "t", "gr", "oz", "lb", "ton" ] }, "weightTo": { "title": "To", "description": "The unit of weight to convert to.", "type": "string", "enum": [ "ug", "mg", "g", "kg", "t", "gr", "oz", "lb", "ton" ] }, "volumeFrom": { "title": "From", "description": "The unit of volume the amount is in.", "type": "string", "enum": [ "mL", "L", "cm3", "m3", "tsp", "tbsp", "floz", "cup", "pt", "qt", "gal", "in3", "ft3", "yd3" ] }, "volumeTo": { "title": "To", "description": "The unit of volume to convert to.", "type": "string", "enum": [ "mL", "L", "cm3", "m3", "tsp", "tbsp", "floz", "cup", "pt", "qt", "gal", "in3", "ft3", "yd3" ] }, "temperatureFrom": { "title": "From", "description": "The unit of temperature the amount is in.", "type": "string", "enum": [ "K", "C", "F" ] }, "temperatureTo": { "title": "To", "description": "The unit of temperature to convert to.", "type": "string", "enum": [ "K", "C", "F" ] }, "areaFrom": { "title": "From", "description": "The unit of area the amount is in.", "type": "string", "enum": [ "mm2", "cm2", "m2", "ha", "km2", "in2", "ft2", "yd2", "acre", "mi2" ] }, "areaTo": { "title": "To", "description": "The unit of area to convert to.", "type": "string", "enum": [ "mm2", "cm2", "m2", "ha", "km2", "in2", "ft2", "yd2", "acre", "mi2" ] }, "speedFrom": { "title": "From", "description": "The unit of speed the amount is in.", "type": "string", "enum": [ "mps", "kmh", "mph", "fps", "kn" ] }, "speedTo": { "title": "To", "description": "The unit of speed to convert to.", "type": "string", "enum": [ "mps", "kmh", "mph", "fps", "kn" ] } } }, "outputs": { "result": { "label": "Converted amount", "description": "The amount in the \"To\" unit.", "format": "number" }, "given": { "label": "From", "description": "The amount and its unit, as entered.", "format": "text" }, "into": { "label": "To", "description": "The unit the amount is converted to.", "format": "text" }, "formula": { "label": "Formula", "description": "How to convert from the one unit to the other.", "format": "text" } }, "defaultAnswer": { "inputs": { "measure": "length", "lengthFrom": "in", "lengthTo": "cm", "weightFrom": "lb", "weightTo": "kg", "volumeFrom": "gal", "volumeTo": "L", "temperatureFrom": "F", "temperatureTo": "C", "areaFrom": "ft2", "areaTo": "m2", "speedFrom": "mph", "speedTo": "kmh", "amount": 1 }, "outputs": { "result": 2.54, "given": "1 in", "into": "centimeters (cm)", "formula": "cm = in × 2.54" }, "text": "1 in = 2.54 centimeters (cm)." }, "examples": [ { "given": { "measure": "length", "amount": 1, "lengthFrom": "in", "lengthTo": "cm" }, "expect": { "result": 2.54, "formula": "cm = in × 2.54" }, "source": "NIST SP 811 (2008) B.8: 1 in = 2.54 cm exactly (content.mdx)" }, { "given": { "measure": "weight", "amount": 150, "weightFrom": "lb", "weightTo": "kg" }, "expect": { "result": 68.0388555 }, "source": "NIST SP 811 (2008) B.8: 1 lb = 0.45359237 kg exactly (content.mdx)" }, { "given": { "measure": "volume", "amount": 1, "volumeFrom": "gal", "volumeTo": "L" }, "expect": { "result": 3.785411784 }, "source": "NIST SP 811 (2008) B.8: 1 US gallon = 231 in³ = 3.785411784 L (content.mdx)" }, { "given": { "measure": "temperature", "amount": 98.6, "temperatureFrom": "F", "temperatureTo": "C" }, "expect": { "result": 37, "formula": "°C = (°F − 32) × 5 ÷ 9" }, "source": "NIST SP 811 (2008) 4.2.1.1: t/°C = (t/°F − 32) ÷ 1.8 (content.mdx)" }, { "given": { "measure": "area", "amount": 1, "areaFrom": "acre", "areaTo": "ft2" }, "expect": { "result": 43560 }, "source": "NIST SP 811 (2008) B.8: 1 acre = 43,560 ft² (content.mdx)" }, { "given": { "measure": "speed", "amount": 60, "speedFrom": "mph", "speedTo": "kmh" }, "expect": { "result": 96.56064 }, "source": "NIST SP 811 (2008) B.8: 1 mi = 1.609344 km exactly; 60 × 1.609344 = 96.56064 (content.mdx)" } ], "sources": [ "NIST SP 811 (2008), Guide for the Use of the International System of Units, section 4.2.1.1 and Appendix B.8. https://www.nist.gov/pml/special-publication-811" ], "related": [ "weight-converter", "kg-to-lbs", "inches-to-cm", "fahrenheit-to-celsius", "cups-to-ml" ], "changelog": [] }