About the m to mm calculation
One meter is exactly 1,000 millimeters, so converting between them is a single multiplication. Enter any value above and the result updates as you type. The SI base unit of length, defined by the distance light travels in 1/299,792,458 of a second. The standard fine unit on engineering drawings and rainfall figures.
Formula
mm = m × 1,000
1 m = 1,000 mm
1 mm = 0.001 mWorked example
To convert 100 m, multiply by 1,000: 100 × 1,000 = 100,000 mm.
Frequently asked questions
How many millimeters are in a meter?
There are 1,000 millimeters in one meter. To convert any amount, multiply the number of meters by 1,000.
How do I convert millimeters back to meters?
Divide instead of multiplying, or equivalently multiply by 0.001. One millimeter is 0.001 meters.
Is this conversion exact?
Yes. Since the international agreement of 1959, the relationship between meters and millimeters is defined exactly rather than measured, so the only rounding here is in how many decimal places we show.
Where is each of these units used?
Meters: the SI base unit of length, defined by the distance light travels in 1/299,792,458 of a second. Millimeters: the standard fine unit on engineering drawings and rainfall figures.
Sources
- NIST Special Publication 811 — Guide for the Use of the International System of Units