Unit Converter

One free converter for every everyday unit — length, weight, volume, area, temperature, speed, time, digital storage, energy, power, pressure, and cooking. Pick a category, pick your two units, get an exact answer. No sign-up, no ads.

Quick answer: A unit converter changes a measurement from one unit to another by going through a common base unit: value in base = your figure × the source unit’s factor, then divide by the target unit’s factor. This free tool converts length, weight, volume, area, temperature, speed, time, digital storage, energy, power, pressure, and cooking units — pick a category, pick the two units, and it converts instantly. No sign-up, works offline once loaded.

How unit conversion actually works — the base-unit method

Every conversion here uses one honest rule: convert your figure into a single base unit for that category, then out to the unit you want. In symbols, result = value × (factor of your unit) ÷ (factor of the target unit), where each factor is how many base units one of that unit equals. Length uses the meter as its base, weight the kilogram, volume the liter, area the square meter, and so on. This is why the answers are exact ratios, not lookup-table approximations.

The two categories that trip people up

Temperature is different. Celsius, Fahrenheit, and Kelvin have different zero points, so you can’t just multiply by a factor — each conversion shifts and scales. This tool applies the real affine formulas: °F = °C × 9/5 + 32, and K = °C + 273.15. Digital storage is the other trap: manufacturers sell drives in decimal units (1 GB = 1,000 MB) while operating systems often report binary units (1 GiB = 1,024 MiB). That gap is why a “1 TB” drive shows as ~931 GiB — this converter includes both so you can see exactly where the missing space went.

Handy exact conversions worth memorising

Conversion	Exact / near value
1 inch	exactly 2.54 cm
1 kilogram	~2.20462 lb
1 mile	1.609344 km (exact)
1 acre	43,560 ft²
1 US cup	16 tablespoons = 236.6 mL
1 kWh	~3,412 BTU
1 horsepower	~0.746 kW
32 psi	~2.2 bar (typical tyre pressure)

Quick FAQ

Is 1 inch exactly 2.54 cm?

Yes — the inch is defined as exactly 2.54 centimetres, so inch/cm/mm conversions are exact rather than rounded.

Why is my hard drive smaller than advertised?

The maker counts in decimal gigabytes (1 GB = 1,000 MB); your operating system usually counts in binary gibibytes (1 GiB = 1,024 MiB). A “1 TB” drive is about 931 GiB. Switch the storage category between GB and GiB to see the difference for any size.

Are the cooking and volume units US or metric?

US customary. A US cup is 236.6 mL and has 16 tablespoons; metric and UK imperial cups differ, so recipes from other countries can vary slightly.

How do I convert Celsius to Fahrenheit by hand?

Multiply by 9/5 and add 32. So 20°C × 9/5 = 36, + 32 = 68°F. For a rough figure, double the Celsius and add 30. The temperature converter shows the exact value.