Measurement & Unit Conversion Calculators
Switching between metric and imperial units, or between related quantities like mass, volume and density, is where small slips turn into big errors. These tools handle the conversion factors and formulas so you can focus on the numbers that matter.
Each calculator shows the formula it uses, so you can check the result or repeat the calculation by hand.
Measurement & Conversion tools
Height Calculator
Free height converter to switch between feet and inches, centimeters, and meters instantly. Includes a reference of common heights and conversion formulas.
Unit Converter
Free unit converter to convert length, weight, temperature, volume, area, and speed between metric and imperial units.
Density Calculator
Free density calculator: solve for density, mass, or volume from the other two in kg, g, lb, liters, mL, gallons, or cubic feet. Common materials listed.
Mass Calculator
Free mass calculator to find mass from density and volume, then convert it between kilograms, grams, pounds, and ounces. Includes common object masses.
Weight Calculator
Convert weight between kilograms, pounds, ounces, grams, stone, US tons, and metric tons at once. Free weight converter with a handy quick reference.
Speed Calculator
Free speed calculator to solve for speed, distance, or time. Works in mph, km/h, m/s, and knots with miles, kilometers, meters, or feet.
Roman Numeral Converter
Convert Roman numerals to numbers and numbers to Roman numerals from 1 to 3999. Free converter with input validation and a handy numeral reference chart.