Length Converter
Convert any length or distance between metric and imperial units — millimetres to inches, metres to feet, kilometres to miles — with the exact factor shown.
How it works
Every length unit here is defined against the metre, so a conversion is one multiplication by a fixed factor. The values are exact by definition — the inch has been exactly 25.4 mm since 1959, which is why metric and imperial lengths convert cleanly rather than approximately.
Only the display is rounded. The calculation runs at full precision and rounds at the end, so converting there and back returns the number you started with rather than drifting.
The nautical mile is the exception worth knowing: it is 1,852 metres exactly, defined from the earth's circumference rather than from the statute mile, which is why sea and air distances never match road distances.
The formula
m → ft
ft = m × 3.2808
ft → m
m = ft ÷ 3.2808
Any pair in this family
result = value × (factor of source ÷ factor of target)
Every unit is defined against the m, so any combination converts in one step.
Worked examples
| Scenario | Working | Result |
|---|---|---|
| 1 metre to feet | 1 ÷ 0.3048 | 3.2808 ft |
| 12 inches to centimetres | 12 × 2.54 | 30.48 cm |
| 5 km to miles | 5 × 0.621371 | 3.1069 mi |
When you'd use it
- Reading a spec sheet written in the other system
- Converting a height or a room measurement
- Checking a running or cycling distance
- Coursework and lab reports needing SI units
Common questions
Is the inch to centimetre conversion exact?
Yes. Since 1959 the international inch has been defined as exactly 25.4 millimetres, so the conversion is a definition rather than a measurement. Any difference you see between converters is display rounding.
Why is a nautical mile different from a mile?
A nautical mile is 1,852 metres, originally one minute of latitude, while a statute mile is 1,609.344 metres. They come from different purposes — navigation against land surveying — so sea and air distances are always longer per mile than road ones.
Which units use the metre as their base?
All of them here. Each unit carries a factor relative to the metre, so any pair converts by dividing one factor by the other. That is why the tool can offer every combination without listing them separately.
Is anything I enter sent anywhere?
No. Every conversion runs in your browser, so nothing you type is uploaded, logged or stored. There is no account and no record of what you converted.