Convert metres to millimetres
1 m = 1000 mm
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How many millimetres are in a metre?
One metre is 1000 millimetres. To convert any amount, multiply by 1000. Going the other way, one millimetre is 0.001 metres.
What is the formula to convert m to mm?
Multiply the metre figure by 1000. So mm = m × 1000. For a quick mental estimate, multiplying by about 1000 gets you within a percent or so, which is close enough for most everyday purposes.
What does a metre actually look like?
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.
And what is a millimetre?
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.
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 m before converting introduces an error the conversion then multiplies.
About m to mm
How to convert metres to millimetres
Multiply by 1000. One metre is 1000 millimetres, and one millimetre is 0.001 metres.
mm = m × 1000
Worked example
10 m = 10000 mm. For a sense of scale, one metre is roughly the height of a kitchen counter plus a bit, and one millimetre is roughly the thickness of a credit card, which is 0.76 mm.
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.
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.
Quick reference
| metres | millimetres |
|---|---|
| 1 m | 1000 mm |
| 2 m | 2000 mm |
| 5 m | 5000 mm |
| 10 m | 10000 mm |
| 25 m | 25000 mm |
| 50 m | 50000 mm |
| 100 m | 100000 mm |
| 1000 m | 1000000 mm |
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 m to a whole number before converting introduces an error that the conversion then multiplies.
Other length conversions
Convert millimetres back to metres, or pick any other pair with the full unit converter. Related: m to km, m to cm, m to mi.