Unit Converter – Length, Weight, Temperature & Speed

What Does the Unit Converter Do?

This converter translates measurements across thirteen categories — length, weight/mass, area, volume, digital storage, time, speed, pressure, energy, power, angle, frequency and temperature — spanning metric, imperial and US customary systems. Enter a value, choose "from" and "to" units, and the answer appears live, together with a table converting your value into every other unit in the category at once. A swap button flips the direction instantly, and a copy button takes the result to your clipboard.

Conversions use exact internationally defined factors (an inch is exactly 25.4 mm, a pound exactly 0.45359237 kg), so results are precise, with very large and very small numbers shown in scientific notation for readability.

How to Convert Units

Pick a category — length, weight, area, volume, digital storage, time, speed, pressure, energy, power, angle, frequency or temperature.
Enter your value and select the source unit.
Choose the target unit — or just read the all-units table below the result.
Use ⇄ to swap direction.

Coverage

Length — nm, µm, mm, cm, m, km, mils, inches, feet, yards, furlongs, miles, nautical miles, astronomical units, light years.
Weight / Mass — µg, mg, carats, grains, g, ounces, troy ounces, pounds, kg, stones, US tons, metric tonnes, UK long tons.
Area — mm², cm², m², hectares, km², square inches, square feet, square yards, acres, square miles.
Volume — ml, cl, litres, cm³, m³, cubic inches, cubic feet, US teaspoons through US gallons, and imperial fluid ounces, pints and gallons.
Digital Storage — bits and bytes, with both decimal (KB, MB, GB, TB, PB) and binary (KiB, MiB, GiB, TiB) units, so you can see exactly why a "1 TB" drive shows as 931 GiB.
Time — nanoseconds through centuries.
Speed — m/s, km/h, mph, ft/s, knots, Mach.
Pressure — pascals, hPa, kPa, MPa, millibars, bars, atmospheres, PSI, torr, mmHg.
Energy — electronvolts, joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, foot-pounds, BTU.
Power — milliwatts, watts, kilowatts, megawatts, metric and mechanical horsepower, BTU/hour.
Angle — degrees, radians, gradians, turns, arcminutes, arcseconds.
Frequency — hertz, kHz, MHz, GHz, RPM.
Temperature — Celsius, Fahrenheit, Kelvin, Rankine, Réaumur (formula-based, not simple factors).

Handy anchors to remember: 1 inch = 2.54 cm, 1 kg ≈ 2.2 lb, 1 mile ≈ 1.6 km, 100 km/h ≈ 62 mph, and 1 knot = 1 nautical mile per hour ≈ 1.85 km/h.

Frequently Asked Questions

Why is temperature converted differently from other units?

Temperature scales have different zero points, not just different step sizes — so conversion needs formulas, not multiplication: °F = °C × 9/5 + 32, K = °C + 273.15. The converter applies these exactly.

What is the difference between a US ton and a metric tonne?

A US (short) ton is 2,000 lb ≈ 907 kg; a metric tonne is exactly 1,000 kg ≈ 2,205 lb. The converter lists both, so international shipping figures never get mixed up.

What is a knot, exactly?

One nautical mile per hour — 1.852 km/h. Nautical miles are based on the Earth's geometry (one minute of latitude), which is why aviation and shipping still use them.

Are stones still used anywhere?

Yes — body weight in the UK and Ireland is commonly given in stones (1 stone = 14 lb ≈ 6.35 kg). The weight category includes them for exactly that use.

Why does my 1 TB hard drive show as about 931 GB?

Drive makers count a terabyte as 1,000,000,000,000 bytes, while Windows reports the same space in binary units (1 GiB = 1,073,741,824 bytes) but labels them "GB". Nothing is missing — it is the same bytes measured two ways. The Digital Storage category lists both, so you can convert between them: 1 TB (decimal) = 931.32 GiB.

What is the difference between a US gallon and an imperial gallon?

A US gallon is 3.785 litres; an imperial (UK) gallon is 4.546 litres — about 20% larger. Recipes and fuel-economy figures are frequently wrong because of this, so the Volume category lists both explicitly rather than a single "gallon".

Which horsepower does the Power category use?

Both. Metric horsepower (PS, used across Europe) is 735.5 W, while mechanical horsepower (used in the US and UK) is 745.7 W — roughly a 1.4% difference, which matters when comparing quoted engine outputs.