Free Calculators Hub
Exact Everyday Unit Converter
Converts within four explicit categories using SI base units, exact international inch and pound definitions, exact US liquid measures, and affine point-temperature formulas.
Limitation: Volume means US liquid measure only, not UK imperial or dry measure.
How to Convert Measurement Units
Choose a category before selecting units. The From and To menus update together, preventing cross-category conversions. Enter a finite number and calculate.
Choose length, mass, temperature points, or US liquid volume.
Names do not guarantee equal sizes
A US fluid ounce, imperial fluid ounce, and dry ounce represent different concepts. This converter labels and supports only the US liquid fluid ounce for volume.
Supported Categories and Definitions
Length supports millimeters, centimeters, meters, kilometers, inches, feet, yards, and miles. Mass supports milligrams, grams, kilograms, avoirdupois ounces, and avoirdupois pounds. Volume supports milliliters, liters, and US customary liquid fluid ounces, cups, pints, quarts, and gallons; UK imperial and dry measures are excluded. Temperature supports Celsius, Fahrenheit, and kelvin temperature points. Linear conversions multiply into a base unit and divide into the target. Temperature uses offsets and rejects values below absolute zero.
Unit Conversion Examples
International inch definition
Category, value, and units
Converted measurement
One inch is exactly 0.0254 meter, so it is exactly 2.54 centimeters.
US liquid gallon
Category, value, and units
Converted measurement
The supported gallon is explicitly the US liquid gallon, exactly 231 cubic inches.
Freezing point of water
Category, value, and units
Converted measurement
The affine point-temperature conversion subtracts the Fahrenheit offset and scales by 5/9.
Preserve significant figures
The converter can display many digits, but your reported precision should not exceed the precision of the measured source value.
Frequently Asked Questions
Still have questions about this calculation?
Try the CalculatorUnit Conversion Factors and Formulas
Defined factors are treated as exact; displayed results are rounded to at most ten decimal places.
Formula
Linear unit conversion
target value = source value × source-to-base factor ÷ target-to-base factor
Exact customary definitions
1 in = 0.0254 m; 1 lb = 0.45359237 kg; 1 US gal = 3.785411784 L
Temperature points
K = °C + 273.15; K = (°F + 459.67) × 5/9
Scientific Background
Factors follow SI and US customary definitions documented by the US National Institute of Standards and Technology. Floating-point arithmetic can limit representation even when a legal definition is exact.
Sources & review
Unit Converter documents the references behind its formulas and assumptions. Always treat results as educational estimates, not personalized professional advice.
Last reviewed
July 21, 2026
Reference
nist.gov
https://www.nist.gov/pml/owm/si-unitsFree Calculator Hub methodology
Free Calculator Hub
/methodology
See our methodology and corrections policy.