This converter turns millimeters into mils instantly, using the exact factor 1 millimeter = 39.37007874 mils. Type any number and the result updates as you go — nothing is sent to a server, so the arithmetic happens entirely in your browser.
One thousandth of a metre — the finest gradation on a standard ruler. One thousandth of an inch, the standard thickness unit for plastic film and PCB traces.
Because the relationship is a simple proportion, one multiplication does the whole job. The table further down gives pre-computed values for the amounts people look up most often, and the result panel also reports the reverse conversion so you can check the figure both ways.
The formula
millimeters- The amount you are converting, measured in millimeters
39.37007874- The exact number of mils in one millimeter
mils- The converted result
How it works, step by step
- Enter the number of millimeters you want to convert.
- The value is multiplied by 39.37007874, the exact conversion factor.
- The result is displayed in mils, rounded for readability.
- The unrounded value and the reverse conversion appear underneath so you can verify it.
Worked examples
Converting 5 millimeters
Multiply 5 by 39.370079. That gives 196.8504 mils. A quick sanity check: one millimeter is larger than one mil, so the number should get bigger — and it does.
Converting 72 millimeters
72 × 39.370079 = 2,834.65 mils. Working backwards, 2,834.65 ÷ 39.370079 returns 72 millimeters, which confirms the factor is applied the right way round.
How to read your score
Frequently asked questions
How many mils are in one millimeter?
Exactly 39.37007874. Every conversion on this page is that single number multiplied by your input, so the result carries no rounding error beyond what is shown.
What is the formula to convert millimeters to mils?
Mils = millimeters × 39.37007874. To reverse it, divide instead: millimeters = mils ÷ 39.37007874, which is the same as multiplying by 0.0254.
Is the millimeter bigger than the mil?
Yes. One millimeter equals 39.3701 mils, so it is the larger unit.
Why does my answer differ slightly from other mm to mils converters?
Most differences come from rounding the factor too early. This tool keeps full double precision through the calculation and only rounds at the final display step, and it also shows the unrounded value so you can see exactly where any difference appears.
What is a millimeter?
One thousandth of a metre — the finest gradation on a standard ruler.
What is a mil?
One thousandth of an inch, the standard thickness unit for plastic film and PCB traces.
Millimeters to mils reference table
| Millimeters | Mils |
|---|---|
| 0.5 mm | 19.685 mil |
| 1 mm | 39.3701 mil |
| 2 mm | 78.7402 mil |
| 3 mm | 118.1102 mil |
| 5 mm | 196.8504 mil |
| 10 mm | 393.7008 mil |
| 15 mm | 590.5512 mil |
| 20 mm | 787.4016 mil |
| 25 mm | 984.252 mil |
| 50 mm | 1,968.5 mil |
| 75 mm | 2,952.76 mil |
| 100 mm | 3,937.01 mil |
| 250 mm | 9,842.52 mil |
| 500 mm | 19,685.04 mil |
| 1000 mm | 39,370.08 mil |
Exact factor: 1 millimeter = 39.37007874 mils. Values rounded for display.