How to Convert Millimetres to Metres (mm to m)
Length conversions come up when reading overseas furniture specs, cycling the Round Island Route in kilometres while a foreign app shows miles, or checking marine distances in the Singapore Strait in nautical miles. This guide shows how to convert millimetres into metres by hand, with examples and a quick-reference table.
The conversion
To convert millimetres to metres, multiply the value by 0.001. To go the other way, divide by the same number (or multiply by 1,000). For a quick estimate, multiply by about 0.001.
Metres = millimetres × 0.001
Worked examples
- 3 mm = 0.003 m
- 12.5 mm = 0.0125 m
- 75 mm = 0.075 m
Millimetres to Metres table
| Millimetres | Metres |
|---|---|
| 1 mm | 0.001 m |
| 2 mm | 0.002 m |
| 5 mm | 0.005 m |
| 10 mm | 0.01 m |
| 20 mm | 0.02 m |
| 25 mm | 0.025 m |
| 50 mm | 0.05 m |
| 100 mm | 0.1 m |
| 250 mm | 0.25 m |
| 500 mm | 0.5 m |
| 1,000 mm | 1 m |
Common questions
Is mm to m exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the Metres to Millimetres converter.
Mistakes to avoid
Mixing similar-sounding units
US and imperial gallons, pints and tons are different sizes, and decimal kilobytes differ from binary kibibytes.
Dropping the units
A bare number without a unit is easy to misread later. Always write the unit with the result.
Rounding the factor too early
Using 3 instead of 3.28 for feet per metre introduces an error of almost 9% before you have started.
Background
Singapore adopted the metric system in the 1970s, replacing imperial units and traditional Chinese measures in most official uses. Metric units are now standard in schools, trade and government, but older units survive in property, markets and imported goods.
Writing the units next to every number while you work is the simplest way to avoid mistakes. If the units do not cancel to leave the one you want, the calculation is set up wrongly.
For everyday use, three or four significant figures are usually enough. Engineering, science and trade documents may need more, and rounding should happen only at the end of a calculation.
For any value, use the Millimetres to Metres Converter or browse all length converters.
Run your own numbers: Millimetres to Metres Converter