Unit Converter
12 free in-browser unit converters — length, weight, and temperature. Type in any unit and see all others update instantly. No signup, no server round-trips.
Length Converter
Convert between millimetres, centimetres, metres, kilometres, inches, feet, yards, miles, and nautical miles instantly. Type in any unit.
Weight Converter
Convert between milligrams, grams, kilograms, metric tonnes, ounces, pounds, stone, and US short tons. Type in any unit, see all conversions.
Temperature Converter
Convert between Celsius, Fahrenheit, Kelvin, and Rankine. Live update as you type in any field. Common reference temperatures shown.
Speed Converter
Convert between m/s, km/h, mph, knots, ft/s, and Mach. Live update as you type in any unit. Common reference speeds shown.
Area Converter
Convert area between mm², cm², m², km², in², ft², yd², acres, and hectares instantly. Type in any unit to update all others.
Volume Converter
Convert volume between ml, litres, m³, cubic inches, cubic feet, US cups, fl oz, gallons, and pints. Live update, no conversion button.
Pressure Converter
Convert pressure between Pascal, kPa, MPa, bar, psi, atm, and mmHg (Torr). Type in any unit and see all others update instantly.
Energy Converter
Convert energy between joules, kilojoules, calories, kcal, watt-hours, kWh, BTU, and electron volts. Live update as you type.
Data Storage Converter
Convert between bits, bytes, KB, MB, GB, TB, and PB (binary, base-2). See all conversions at once as you type any value.
Time Converter
Convert time between milliseconds, seconds, minutes, hours, days, weeks, months, and years. Instant live update in any field.
Angle Converter
Convert angles between degrees, radians, gradians, arcminutes, arcseconds, and full revolutions. Live update as you type.
Fuel Efficiency Converter
Convert fuel efficiency between mpg (US), mpg (UK), km/L, and L/100km. Handles the inverse relationship between consumption and efficiency.
About these unit converters
All converters run client-side using exact conversion factors defined by international standards (SI, imperial, and US customary systems). Type a value into any field and every other unit updates immediately. There is no "convert" button to click — the result is always live.
What is the difference between metric and imperial?
The metric system (SI) uses base units like metres, grams, and Celsius with decimal prefixes (kilo-, milli-, etc.). The imperial system, used primarily in the United States, uses units like inches, feet, pounds, and Fahrenheit that have irregular conversion ratios (e.g., 12 inches in a foot, 3 feet in a yard, 1,760 yards in a mile). These converters handle both seamlessly.
How precise are the conversions?
Conversions use JavaScript double-precision floating-point arithmetic (IEEE 754). For most practical purposes this gives 15–16 significant digits of precision. Results are displayed rounded to 6 significant figures to avoid showing floating-point noise.
Why is absolute zero −273.15°C?
Absolute zero (0 K) is the theoretical minimum temperature, at which point molecular motion stops entirely. The Celsius scale is offset from Kelvin by exactly 273.15 — so 0 K = −273.15°C. It is physically impossible to reach or go below this temperature.