Convert millimetres to metres
1 mm = 0.001 m
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How many metres are in a millimetre?
One millimetre is 0.001 metres. To convert any amount, multiply by 0.001. Going the other way, one metre is 1000 millimetres.
What is the formula to convert mm to m?
Multiply the millimetre figure by 0.001. So m = mm × 0.001. For a quick mental estimate, dividing by about 1000 gets you close enough for most everyday purposes.
What does a millimetre actually look like?
One millimetre is roughly the thickness of a credit card, which is 0.76 mm. The millimetre is the working unit of engineering drawings and machining tolerances almost everywhere metric is used, because it avoids decimals for most part dimensions.
And what is a metre?
One metre is roughly the height of a kitchen counter plus a bit. The metre has been defined since 1983 as the distance light travels in a vacuum in 1/299,792,458 of a second — a definition that ties it to a physical constant rather than to any object.
Is this conversion exact?
Yes. Since the 1959 international yard and pound agreement, the imperial and metric systems are related by exact definitions rather than measurements — the inch is exactly 25.4 mm and the pound exactly 0.45359237 kg. Everything derived from those, including this conversion, is therefore exact. Round at the end rather than partway through, since rounding mm before converting introduces an error the conversion then multiplies.
About mm to m
How to convert millimetres to metres
Multiply by 0.001. One millimetre is 0.001 metres, and one metre is 1000 millimetres.
m = mm × 0.001
Worked example
10 mm = 0.01 m. For a sense of scale, one millimetre is roughly the thickness of a credit card, which is 0.76 mm, and one metre is roughly the height of a kitchen counter plus a bit.
About the millimetre
The millimetre is the working unit of engineering drawings and machining tolerances almost everywhere metric is used, because it avoids decimals for most part dimensions.
About the metre
The metre has been defined since 1983 as the distance light travels in a vacuum in 1/299,792,458 of a second — a definition that ties it to a physical constant rather than to any object.
Quick reference
| millimetres | metres |
|---|---|
| 1 mm | 0.001 m |
| 2 mm | 0.002 m |
| 5 mm | 0.005 m |
| 10 mm | 0.01 m |
| 25 mm | 0.025 m |
| 50 mm | 0.05 m |
| 100 mm | 0.1 m |
| 1000 mm | 1 m |
Getting it right
This conversion is exact by definition, so the only limit on accuracy is how many digits you keep. Round at the end rather than partway through — rounding mm to a whole number before converting introduces an error that the conversion then multiplies.
Other length conversions
Convert metres back to millimetres, or pick any other pair with the full unit converter. Related: mm to km, mm to cm, mm to mi.