Unit Converters

Unit converters for length, weight, temperature and more

Unit conversion is the quiet glue that lets a recipe from one country work in another kitchen, a part spec written in millimetres fit a drawing marked in inches, and a weather report in Celsius make sense to someone who thinks in Fahrenheit. The converters here move a value from one unit to an equivalent in another while keeping its real-world meaning intact. They cover physical quantities — length, mass, temperature, area, volume, speed, pressure and energy — as well as digital ones like data storage and time.

Where exact conversion matters

Some conversions are forgiving and some are not. Eyeballing "about two and a half centimetres" for an inch is fine when you're hanging a picture, but a machinist cutting a part, a nurse calculating a dose by body weight, or a developer sizing a buffer in mebibytes needs the precise factor every time. Temperature is a special case because it isn't a simple multiplication: Celsius and Fahrenheit have different zero points, so you have to shift the scale as well as scale it. Getting that offset wrong is the classic conversion bug, and these tools handle it for you.

Precision and recognised standards

Good converters rely on internationally agreed definitions rather than rounded shortcuts. One inch is exactly 25.4 millimetres by definition, a pound is 0.45359237 kilograms, and a nautical mile is a fixed 1,852 metres — these are standards, not approximations. Data units carry their own subtlety: a kilobyte can mean 1,000 bytes (the SI decimal sense) or 1,024 bytes (the binary kibibyte), and mixing the two is why a drive's advertised size never quite matches what your operating system reports. The tools here keep these factors consistent so your results match the standard, not a guess.

How to pick and use a converter

Choose the converter that names your quantity rather than a unit that merely looks similar — weight and volume are not interchangeable even though a litre of water happens to weigh a kilogram. Enter the source value, confirm the direction of the conversion, and pay attention to how many decimal places you actually need; quoting a measurement to six digits when your input was rounded to one only invents false precision. For repeated work, convert once and write the factor down so the rest of your figures stay consistent.

Every converter, and when you'd reach for it

• Length— inches, feet, meters, miles and the nautical mile for charts and flight plans.
• Weight— grams, pounds, stones and tons, with the avoirdupois-versus-troy and short-versus-metric-ton traps spelled out.
• Temperature— the one conversion that needs a formula, not a multiplier, because the scales have different zero points.
• Volume— milliliters to gallons, keeping US and UK measures separate so a recipe or fuel figure stays honest.
• Area— square meters, acres and hectares, with the squared-factor rule for converting two-dimensional space.
• Speed— mph, km/h, knots and Mach, including why Mach shifts with altitude.
• Data storage— bits and bytes across both the decimal (KB) and binary (KiB) conventions that explain your "missing" drive space.
• Pressure— pascals, bar, psi and mmHg for tires, weather and blood-pressure readings.
• Energy— joules, food Calories, kWh and BTU, letting you compare gas and electric heating on one scale.
• Time— milliseconds to years, exact through weeks and approximate beyond.