Unit Converter — Length, Mass, Temperature, Data & More
Convert between units in 9 categories — length, mass, temperature, area, volume, time, speed, digital data, and energy. Live conversion, exact SI factors, formula shown.
| 1 Meter = | 0.001 | Kilometer (km) |
| 1 Meter = | 100 | Centimeter (cm) |
| 1 Meter = | 1,000 | Millimeter (mm) |
| 1 Meter = | 1,000,000 | Micrometer (μm) |
| 1 Meter = | 1,000,000,000 | Nanometer (nm) |
| 1 Meter = | 0.00062137 | Mile (mi) |
About this tool
WRRK's unit converter handles the conversions you actually search for: kilometers to miles, kilograms to pounds, Celsius to Fahrenheit, square meters to acres, liters to US gallons, hours to seconds, megabytes to mebibytes, kilowatt-hours to BTU. Nine categories cover the units 99% of users need, and every conversion factor is the official SI or NIST definition — so “1 mile to km” returns 1.609344 km exactly, not the rounded textbook 1.6.
Two things to know about the digital-data category. The decimal prefixes (KB, MB, GB) are powers of 1000 — used by SI and storage manufacturers. The binary prefixes (KiB, MiB, GiB) are powers of 1024 — used by most operating systems and memory. A “1 TB” drive (1 trillion bytes) shows up as ~931 GiB in your file manager, which is why your “1 TB” SSD looks “smaller” than advertised. Both prefix systems are listed.
Temperature has its own math. Celsius and Fahrenheit are affine scales (different zero points, different step sizes), so the conversion needs both a multiplier and an offset: °F = °C × 9/5 + 32. Kelvin and Rankine share absolute zero with their respective scales, but still need offsets to interconvert. The calculator handles all four temperature scales correctly and displays the exact formula it used.
How to use the unit converter (5 steps)
- Pick a category. Length, mass, temperature, area, volume, time, speed, digital data, or energy. Each opens its own list of units.
- Pick the 'from' unit. Choose the unit your input value is in. Defaults are sensible (e.g. meter for length, kilogram for mass).
- Pick the 'to' unit. What you want the answer in. The calculator updates instantly.
- Enter the value. Type a number — supports decimals and scientific notation. The result shows with up to 8 significant digits.
- Read the formula. Below the result, the conversion ratio (or special temperature formula) is shown. Useful for spreadsheets or homework.
What you can convert
| Category | Units included |
|---|---|
| Length | km, m, cm, mm, μm, nm, mile, yard, foot, inch, nautical mile |
| Mass | tonne, kg, g, mg, μg, lb, oz, stone, US ton, UK ton, carat |
| Temperature | °C, °F, K, °R |
| Area | km², m², cm², mm², hectare, acre, mi², yd², ft², in² |
| Volume | kL, L, mL, m³, US/UK gallon, quart, pint, cup, fl oz, tbsp, tsp, ft³, in³, oil bbl |
| Time | ms, s, min, hour, day, week, month, year, μs, ns |
| Speed | m/s, km/h, mph, ft/s, knot, Mach |
| Data | bit, B, KB/MB/GB/TB/PB (decimal), KiB/MiB/GiB/TiB (binary) |
| Energy | J, kJ, cal, kcal, Wh, kWh, BTU, eV, ft·lb |
Use cases
- Cooking — converting US recipes to metric and back
- Travel — kilometers to miles, kilograms to pounds for luggage
- Engineering and physics homework — exact SI conversions
- Real estate — square feet to square meters, acres to hectares
- Fitness — calories vs kJ, miles vs km on running apps
- Web/dev work — file sizes between binary and decimal prefixes
- Climate / weather — °C to °F across regions
- Trading — barrels of oil to liters, ton vs tonne
Frequently asked questions
+−How accurate are these conversions?
All factors are the official SI / NIST definitions (e.g. 1 mile = 1609.344 m exactly, 1 pound = 453.59237 g exactly). Results are computed in IEEE 754 double precision and shown to up to 8 significant digits. For everyday use this is far more accurate than any practical measurement you'll make.
+−What's the difference between MB and MiB?
MB (megabyte) is 1,000,000 bytes — used by storage manufacturers and SI standards. MiB (mebibyte) is 1,048,576 bytes (2^20) — used by most operating systems when they say 'memory' or 'file size'. The 'data' category includes both. A '1 TB' drive holds about 931 GiB.
+−Why does Celsius to Fahrenheit need a special formula?
Temperature scales don't share a zero point — they're affine, not linear. So you can't just multiply by a factor; you need °F = °C × 9/5 + 32. Kelvin and Rankine share their zero points with thermodynamic absolute zero, but their unit sizes still differ. The calculator handles all four temperature scales correctly.
+−What's the difference between mass and weight?
In physics, mass is the amount of matter (kg, g) and weight is the force gravity exerts on it (newtons). In everyday English, 'weight' is used interchangeably with mass. This category converts mass — the same quantity that scales report.
+−Do you support imperial vs US measurement differences?
Yes for the major splits — US gallons (3.785 L) and imperial gallons (4.546 L) are separate units, and so are short ton (US, 907.18 kg) vs long ton (UK, 1016.05 kg). Volume and mass categories include both versions.
+−Why is 1 mph not exactly 1.609 km/h?
Because 1 mile is exactly 1609.344 meters, 1 mph is exactly 1.609344 km/h. The popular '1 mile ≈ 1.6 km' is a useful approximation, not an exact ratio. The calculator uses the exact value, so distance × speed conversions stay accurate over long ranges.
+−Can I convert between non-SI units (e.g. furlongs, pecks)?
The current categories cover the units 99% of people search for. Niche units (furlongs, hogsheads, troy ounces, BTUs of various flavours) aren't included to keep the lists scannable. Send a request via WRRK if you need one added.