Unit Converter - Length, Weight, Temperature & More
Convert length, weight, temperature, area, volume, speed, time, digital storage, pressure, energy and angle — and see your value in every unit of the category at once.
1 Kilometre (km) in every unit
| Unit | Value |
|---|---|
| Kilometre (km) | 1 |
| Metre (m) | 1,000 |
| Centimetre (cm) | 100,000 |
| Millimetre (mm) | 1,000,000 |
| Micrometre (µm) | 1,000,000,000 |
| Nanometre (nm) | 1,000,000,000,000 |
| Mile (mi) | 0.621371 |
| Yard (yd) | 1,093.61 |
| Foot (ft) | 3,280.84 |
| Inch (in) | 39,370.08 |
| Nautical mile (nmi) | 0.539957 |
What is a Unit Converter?
A unit converter rescales a measurement from one unit into another. Internally every unit in a category is defined as a multiple of one base unit — metres for length, kilograms for mass, litres for volume — so a conversion is one multiplication and one division. Temperature is the exception: because its scales have different zero points, it needs offsets rather than plain scaling, and is handled separately.
Eleven Categories, 100+ Units
- Length — kilometres, metres, centimetres, millimetres, micrometres, nanometres, miles, yards, feet, inches, nautical miles
- Weight & mass — tonnes, kilograms, grams, milligrams, pounds, ounces, stones, US and UK tons
- Temperature — Celsius, Fahrenheit, Kelvin, Rankine
- Area — square kilometres, hectares, dunams, square metres, acres, square miles, square feet and more
- Volume — cubic metres, litres, millilitres, US and Imperial gallons, cups, pints, quarts, tablespoons, oil barrels
- Speed — metres per second, km/h, mph, knots, feet per second
- Time — nanoseconds through years
- Digital storage — bits, bytes, and both decimal (KB, MB, GB) and binary (KiB, MiB, GiB) multiples
- Pressure — pascals, kilopascals, bar, atmospheres, psi, mmHg
- Energy — joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, BTU
- Angle — degrees, radians, gradians, turns, arcminutes, arcseconds
Common Conversions
cm to Inches
One inch is exactly 2.54 cm — a defined, not measured, value.
kg to Pounds
One kilogram is 2.204623 lb; one pound is exactly 0.45359237 kg.
°C to °F
Multiply by 9/5 and add 32. 25°C is 77°F.
km to Miles
One mile is exactly 1,609.344 metres.
GB to GiB
Decimal and binary multiples differ by about 7% at gigabyte scale.
Cups to mL
Useful for recipes written for a different measurement system.
How to Convert Units
- Choose the category you are working in.
- Enter your value.
- Pick the source and target units, or use the swap button to reverse them.
- Read the result, plus the rate in both directions.
- Scroll down to see your value expressed in every unit of the category at once.
Why KB and KiB Are Not the Same
Storage manufacturers use decimal SI multiples: a kilobyte is 1,000 bytes and a terabyte is 1012 bytes. Operating systems have traditionally used binary multiples: a kibibyte is 1,024 bytes and a tebibyte is 240. This is why a "1 TB" drive shows up as roughly 931 GB in Windows — nothing is missing, the two systems are simply counting differently. Both sets of units are included so you can see the gap explicitly.
Exact Definitions vs Measured Values
Many conversions people assume are approximate are actually exact by international agreement: an inch is exactly 25.4 mm, a pound is exactly 0.45359237 kg, a nautical mile is exactly 1,852 m, and a calorie is exactly 4.184 joules. This converter uses those exact definitions and rounds only for display, so results are as precise as the definitions allow.
US and Imperial Units Are Different
A US gallon is 3.785 litres; an Imperial gallon is 4.546 litres — about 20% larger. US and UK pints, quarts and fluid ounces differ too, and a US ton (2,000 lb) is lighter than a UK long ton (2,240 lb). Both variants are listed separately so you never have to guess which one a recipe, spec sheet or shipping document means.
Who This Converter Is For
- Engineers and technicians working across measurement systems
- Developers converting data sizes and time units
- Students working through physics and chemistry problems
- Cooks following recipes from another country
- Travellers reading local speed, temperature and distance signs
- Anyone shipping, buying or specifying in unfamiliar units
❓ Frequently Asked Questions
What can this unit converter handle?
Eleven categories: length, weight and mass, temperature, area, volume, speed, time, digital storage, pressure, energy and angle — with more than 100 units in total.
How does it convert between units?
Every unit is defined as a multiple of its category's base unit, so a conversion is one multiplication and one division. Temperature is handled separately because it needs offsets, not just scaling.
How do I convert Celsius to Fahrenheit?
Multiply by 9/5 and add 32. So 25°C is 77°F. The converter also handles Kelvin and Rankine.
How many pounds are in a kilogram?
One kilogram is 2.204623 pounds, and one pound is exactly 0.45359237 kilograms.
What is the difference between KB and KiB?
A kilobyte (KB) is 1,000 bytes in the decimal SI convention used by storage manufacturers, while a kibibyte (KiB) is 1,024 bytes in the binary convention used by operating systems. Both are included.
Why does one input show every unit at once?
Because it saves repeated conversions. Enter a value once and read it off in every unit in the category, which makes cross-checking much faster.
Are the conversion factors exact?
Where an exact definition exists it is used — an inch is exactly 25.4 mm and a mile is exactly 1,609.344 m. Values are then rounded for display only.
Does it support US and Imperial gallons?
Yes. US and Imperial gallons differ by about 20%, so both are listed separately along with US cups, pints, quarts and fluid ounces.
Can I convert very large or very small numbers?
Yes. Extremely large or small results are shown in scientific notation so precision is not lost.
Is this unit converter free?
Yes. It is free, needs no installation, and runs entirely offline in your browser.