- How accurate are the conversions?
- Every conversion factor is based on standard, internationally recognized definitions (SI, US customary and UK imperial units). Under each result the formula is shown, marked “exact, by definition” where the factor is exact (the inch is exactly 2.54 cm, the pound exactly 0.45359237 kg) and “rounded” where it isn't. Results are computed in full floating-point precision and rounded only for display — choose decimal places, significant figures, scientific notation and your number separators under “Precision and number format”.
- How many categories and units are supported?
- 15 categories — length, weight & mass, temperature, area, volume, speed, fuel economy, time, pressure, energy, power, data storage, angle, lakh & crore, and cooking — with over 120 units, including UK pints and gallons, metric cups, torr, and Indian land units (gaj, cent, marla, kanal, guntha and the bigha of several states).
- Can I type 5'11" or 6 ft 2 in?
- Yes. The value box reads amounts the way people write them: 5'11", 6 ft 2 in, 3 st 4 lb, 1/4 cup, 1 ½ cups, 2 h 30 min, 1:30:00 and simple sums like 2 m + 30 cm. Heights, weights and times also come back in mixed units (5 ft 11 in, 11 st 4 lb, 2:30:00). Both 3.5 and 3,5 work: pick how your numbers are written under “Precision and number format”.
- Are cups and gallons US or UK?
- Both are there, labelled: a US cup is 236.6 mL, a metric cup (UK, Australia, Canada) 250 mL and a traditional UK cup 284 mL; a US gallon is 3.785 L and a UK gallon 4.546 L. The popular cups and gallons pages use US measures and say so.
- How do I convert cups to grams?
- Open Cooking and pick the ingredient — flour, sugar, brown sugar, butter, rice and more. A cup of flour weighs about 125 g but a cup of butter 227 g, so the ingredient matters. The weights are standard references; how a cup is filled changes them a little.
- Is there a dedicated page for common conversions?
- Yes. The most-searched conversions — kg to lbs, cm to inches, Celsius to Fahrenheit, ml to cups, mph to km/h and more — each have their own focused page with a worked example and a reference table. Browse them all in the “Popular conversions” list above, or use the full converter here for anything else.
- Why do kilobyte and kibibyte give different results?
- Data storage includes both decimal units (kB, MB, GB — powers of 1000, the convention used for storage capacity and network speeds) and binary units (KiB, MiB, GiB — powers of 1024, the convention operating systems often use for memory). Pick the one that matches what you're comparing against.
- Can I share a conversion or convert a whole list?
- Yes. “Link” copies an address that opens the same category, units and value (kept in the part of the address after #, which isn't sent to any server). “Convert a list” takes a pasted column of values and gives the converted column to copy or download as CSV.
- How is temperature converted differently from other units?
- Celsius, Fahrenheit, and Kelvin aren't simple multiples of one another — 0°C isn't 0°F — so temperature uses its own formula instead of a fixed multiplier. Values below absolute zero (−273.15 °C) are refused, because no temperature can be lower. Fuel economy is the other exception: L/100 km goes down as mpg goes up, so it's a division.
- Is my data sent to a server?
- No. All conversions run entirely in your browser using JavaScript. Nothing is uploaded or logged. Your last category, units, value, ingredient and number format are saved in this browser only, so they're there next time.
- Is the Unit Converter really free?
- Yes. There's no account to create, no card to enter, and no trial clock ticking in the background. All 15 categories and over 120 units are available immediately, with no conversion limit.
- Do I have to create an account first?
- No. There's no account system at all, so there's nothing to sign up for and nothing to install. Pick a category, type a value, and every unit updates at once.