MM to Meters Converter

Common questions

How many meters is 1 mm?

0.001 m, because one thousand millimetres make a metre. The pattern holds at every size: 5 mm is 0.005 m, 7 mm is 0.007 m, 250 mm is 0.25 m, 1,500 mm is 1.5 m and 12,345 mm is 12.345 m. The conversion moves the decimal point three places to the left, and the displayed result rounds longer inputs to twelve significant digits.

What is the formula for mm to meters?

Metres = millimetres / 1,000, and millimetres = metres × 1,000 in the other direction, so 2.5 m is 2,500 mm. Milli is the SI prefix for a thousandth of the base unit, so a millimetre is one thousandth of a metre by definition rather than by measurement. The factor carries no error, and any rounding you see comes from the display, which prints twelve significant digits.

Which way does the decimal point move?

Left by three places going from millimetres to metres: 7 mm becomes 0.007 m and 1,800 mm becomes 1.8 m. Right by three places going the other way: 1.8 m becomes 1,800 mm. The Swap units button between the two boxes reverses the pair, so this page turns into a metres to millimetres converter without a reload.

Is 1 mm exactly 0.001 m, or is that rounded?

Exactly, and by definition. The metre has been fixed since 1983 by defining the speed of light as 299,792,458 metres per second, and milli means one thousandth, so the millimetre is one thousandth of that metre. Dividing by 1,000 only shifts the decimal point, so the arithmetic itself is exact. The display is where limits appear: twelve significant digits, with values below 0.000001 shown in exponential notation, so 0.0001 mm reads 1e-7 m.

Does dividing by 1,000 also work for square and cubic millimetres?

No, and this is where the mistake usually happens. Area squares the ratio, so 1,000,000 mm² is 1 m², and volume cubes it, so 1,000,000,000 mm³ is 1 m³. The Area category chip above the converter has square metres, and its two dropdowns always include square millimetres; the uncommon units switch in the readout is what adds that unit to the list under the answer. The Volume category lists cubic metres, litres and millilitres but no cubic millimetre, so cube the 1,000 yourself there: 1,000 mm³ is 1 mL.

What is 1,800 mm in feet and inches?

The list under the answer already has it, because the converter works out every common length unit at once rather than one target at a time. Type 1800 in the From box and the headline reads 1.8 m, with 180 cm, 0.0018 km, 70.8661417323 in, 5.90551181102 ft, 1.96850393701 yd and 0.00111846814603 mi in the list below. Values are shown to twelve significant digits, and Copy result copies the headline exactly as printed, without the thousands separators.

Why does the page open on mm and m when I last converted something else?

Because a page that names a pair should show that pair. This one sets millimetres and metres on arrival, ahead of whatever the converter last remembered, and it leaves the main unit converter's own memory alone: go back there and it is still on the pair you left it on. The number you last typed does come with you, since it is usually the one you are still working on.