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📏 Unit Converter

Convert between common and scientific units in real time.

Millimeters (mm) Centimeters (cm) Meters (m) Kilometers (km) Inches (in) Feet (ft) Yards (yd) Miles (mi) Micrometers (µm) Nanometers (nm) Nautical Miles (nmi) Astronomical Units (AU)

Milligrams (mg) Grams (g) Kilograms (kg) Tonnes (t) Pounds (lb) Ounces (oz) Stone (st) Slug

Celsius (°C) Fahrenheit (°F) Kelvin (K) Rankine (°R)

Milliliters (mL) Liters (L) Cubic meters (m³) Cubic centimeters (cm³) Cubic millimeters (mm³) Cubic inches (in³) Cubic feet (ft³) Gallons (US) Gallons (UK) Oil Barrel (bbl) Cubic kilometers (km³)

Square millimeters (mm²) Square centimeters (cm²) Square meters (m²) Hectares (ha) Square kilometers (km²) Square inches (in²) Square feet (ft²) Square yards (yd²) Square miles (mi²) Acre

Meters per second (m/s) Kilometers per hour (km/h) Miles per hour (mph) Knot (kn) Feet per second (ft/s) Speed of light (c)

Nanoseconds (ns) Microseconds (µs) Milliseconds (ms) Seconds (s) Minutes (min) Hours (h) Days (d) Weeks (wk) Months (mo) Years (yr) Centuries (cent)

Joules (J) Kilojoules (kJ) Megajoules (MJ) Gigajoules (GJ) Calories (cal) Kilocalories (kcal) Watt-hours (Wh) Kilowatt-hours (kWh) Electronvolt (eV) BTU

Pascals (Pa) Kilopascals (kPa) Megapascals (MPa) Bar Atmospheres (atm) Pounds per square inch (psi) Torr

Convert every unit in a category at once

Type a value into any box and every other unit in that group updates immediately — you do not pick a “from” and a “to” unit. That makes it quick to sanity-check an answer against several units at the same time.

What is covered

Length — mm, cm, m, km, inches, feet, yards, miles, micrometres, nanometres, nautical miles, astronomical units.
Mass — mg, g, kg, tonnes, pounds, ounces, stone, slugs.
Temperature — Celsius, Fahrenheit, Kelvin, Rankine.
Volume & area — mL, L, m³, cubic inches and feet, US and UK gallons, barrels; mm² to square miles, hectares and acres.
Speed, time, energy, pressure — m/s, km/h, mph, knots, the speed of light; nanoseconds to centuries; joules, calories, kWh, electronvolts, BTU; pascals, bar, atmospheres, psi, torr.

Conversion factors are exact where an exact definition exists (an inch is exactly 25.4 mm, a pound exactly 0.45359237 kg). Everything is computed locally — the converter works with no internet connection at all.