Unit Converter
Convert length, weight, temperature, speed, area, volume and data units instantly. See the formula used with every conversion.
Length Converter
1 km = 0.6213711922 mi
Formula: km × 0.621371 = mi
Quick Conversions — Length
Length — All Units
| Unit | Symbol | Value in 1 m |
|---|---|---|
| Millimetres | mm | 1000 |
| Centimetres | cm | 100 |
| Metres | m | 1 (base) |
| Kilometres | km | 0.001 |
| Inches | in | 39.370079 |
| Feet | ft | 3.2808399 |
| Yards | yd | 1.0936133 |
| Miles | mi | 0.00062137119 |
How to Use the Unit Converter
Select Category
Click a category tab — Length, Weight, Temperature, Speed, Area, Volume or Data.
Choose Units
Select your source unit from the left dropdown and your target unit from the right dropdown.
Enter Value
Type a number in the input field. The result updates instantly with the formula used.
Swap or Copy
Use the swap button to reverse the conversion, or click the copy icon to copy the result.
Frequently Asked Questions
How does the unit converter calculate results?
All unit conversions (except temperature) use a base-unit system. Each unit has a defined factor relative to a base unit (e.g., metres for length). To convert, the input is multiplied by the source factor to reach the base, then divided by the target factor. Temperature uses direct formulas because it requires addition and subtraction, not just multiplication.
Why does temperature conversion work differently?
Temperature scales don't share a common zero point. Celsius and Fahrenheit start at different values (water freezes at 0°C and 32°F), while Kelvin starts at absolute zero. This means temperature conversion requires the formula (°F − 32) × 5/9 = °C rather than a simple multiplication factor.
What is the difference between UK and US fluid ounces?
A UK (imperial) fluid ounce is 28.41 ml while a US fluid ounce is 29.57 ml. They differ by about 4%. This also affects pints and gallons — a UK pint is 568 ml and a US pint is 473 ml. Always check which system is being used when following recipes or measuring liquids.
How are data units calculated (KB, MB, GB)?
This converter uses binary prefixes: 1 KB = 1,024 bytes, 1 MB = 1,024 KB, 1 GB = 1,024 MB, and 1 TB = 1,024 GB. This is the standard used by operating systems. Note that storage manufacturers often use decimal prefixes (1 KB = 1,000 bytes), which is why a '1 TB' drive shows as ~931 GB in Windows.
How accurate are the conversion results?
Conversions are calculated using double-precision floating-point arithmetic (IEEE 754), the same standard used by all modern computers. Results are displayed to up to 10 significant figures. For scientific work, always verify results against authoritative standards such as NIST or the UK National Physical Laboratory.
Related Tools
BMI Calculator
Calculate BMI in metric or imperial with UK/US health guidelines.