Millimeters to inches conversion table
Every row is computed with the exact factor the converter above uses:
1 mm = 0.03937 in (in = mm × 0.03937).
Looked-up values are rounded to 3 decimals;
type any amount into the tool for other millimeters values.
| mm | in |
|---|---|
| 0.5 mm | 0.02 in |
| 1 mm | 0.039 in |
| 1.5 mm | 0.059 in |
| 2 mm | 0.079 in |
| 2.5 mm | 0.098 in |
| 3 mm | 0.118 in |
| 3.5 mm | 0.138 in |
| 4 mm | 0.157 in |
| 4.5 mm | 0.177 in |
| 5 mm | 0.197 in |
| 6 mm | 0.236 in |
| 6.35 mm | 0.25 in |
| 7 mm | 0.276 in |
| 8 mm | 0.315 in |
| 9 mm | 0.354 in |
| 10 mm | 0.394 in |
| 11 mm | 0.433 in |
| 12 mm | 0.472 in |
| 13 mm | 0.512 in |
| 14 mm | 0.551 in |
| mm | in |
|---|---|
| 15 mm | 0.591 in |
| 16 mm | 0.63 in |
| 17 mm | 0.669 in |
| 18 mm | 0.709 in |
| 19 mm | 0.748 in |
| 20 mm | 0.787 in |
| 21 mm | 0.827 in |
| 22 mm | 0.866 in |
| 23 mm | 0.906 in |
| 24 mm | 0.945 in |
| 25 mm | 0.984 in |
| 26 mm | 1.024 in |
| 27 mm | 1.063 in |
| 28 mm | 1.102 in |
| 29 mm | 1.142 in |
| 30 mm | 1.181 in |
| 32 mm | 1.26 in |
| 35 mm | 1.378 in |
| 38 mm | 1.496 in |
| 40 mm | 1.575 in |
| mm | in |
|---|---|
| 45 mm | 1.772 in |
| 50 mm | 1.969 in |
| 55 mm | 2.165 in |
| 60 mm | 2.362 in |
| 65 mm | 2.559 in |
| 70 mm | 2.756 in |
| 75 mm | 2.953 in |
| 80 mm | 3.15 in |
| 90 mm | 3.543 in |
| 100 mm | 3.937 in |
| 110 mm | 4.331 in |
| 120 mm | 4.724 in |
| 125 mm | 4.921 in |
| 150 mm | 5.906 in |
| 200 mm | 7.874 in |
| 250 mm | 9.843 in |
| 300 mm | 11.811 in |
| 400 mm | 15.748 in |
| 500 mm | 19.685 in |
| 1000 mm | 39.37 in |
Small units, precise work
Millimeters are where measurements get serious. When a centimeter is too coarse, you reach for the millimeter, and that’s exactly the scale where the metric-imperial clash gets annoying. The fix is one ratio: there are 25.4 millimeters in an inch. Flip it and one millimeter is 0.0393701 inches.
Type your value, read the result the instant it appears. Everything calculates locally in your browser, so there’s no waiting and nothing uploaded anywhere.
Hardware, bolts, and drill bits
This is the conversion every maker and DIYer needs. Fasteners are a mess of mixed standards. A drill bit might be sold as 6 mm in one shop and 15/64 inch in another, and those are nearly the same hole (6 mm is 0.2362 inches). Wrench sizes, socket sets, sheet metal thickness: half of it is metric, half imperial, and nobody labels both.
The 10 mm socket, the one that always goes missing, is 0.3937 inches, a hair under 25/64. A 13 mm is 0.5118 inches, just past a half inch. Wire and sheet gauges add another layer. A 1.5 mm² cable, a 0.8 mm steel panel, an M4 screw with a 4 mm shank: knowing those in inches helps when your tools or parts come from the other side of the standards divide. Drop the number in and you’ll see whether two parts actually match or just look close.
Rainfall and the tiny stuff
Weather reports outside the US give rainfall in millimeters. “25 mm of rain overnight” sounds modest until you convert it: that’s almost exactly one inch falling across every square foot. A 50 mm downpour is about two inches, which is a lot of water.
Small physical dimensions live here too. Phone thickness (often 7 to 9 mm), the diameter of a coin, the lead in a mechanical pencil (0.5 mm is 0.0197 inches). When a spec sheet only gives one system, this gets you the other.
Two anchors worth memorizing: 10 mm is 0.393701 inches, which is also exactly 1 cm, and 25.4 mm is one inch on the nose. The rest of the values people reach for sit in the conversion table at the top of the page.
Running the tool
Enter millimeters, and the inch figure updates live with no button to click. The dropdown lets you change either unit, so switching to centimeters or going the reverse direction stays on this page. The reference table up top carries the values folks check most often.
Results round to a sensible precision for general use. If you’re machining to a thousandth of an inch, work from the exact 25.4 mm per inch ratio yourself, since that figure carries no rounding error.
Questions people ask
How many mm in an inch?
25.4 millimeters, exactly. It’s a defined value, so there’s no approximation involved. That makes inch-to-mm conversions clean.
What is 10 mm in inches?
0.3937 inches, a whisker under 25/64 inch. That’s the “missing” 10 mm socket everyone hunts for, and it’s also exactly 1 cm, so the same figure covers both.
How many inches is 13 mm?
0.5118 inches, just past the half-inch mark. A 13 mm socket and a 1/2 inch socket (12.7 mm) are close enough to strip a bolt if you grab the wrong one, so the 0.3 mm gap matters.
How do I convert mm to inches by hand?
Divide the millimeters by 25.4. So 38 mm divided by 25.4 is about 1.496 inches, basically 1.5 inches. Multiplying by 0.0393701 gives the same answer.
Is 10 mm the same as 1 cm in inches?
It is. 10 mm equals 1 cm, and both convert to 0.393701 inches. The metric system stacks neatly in tens, which is why this works out evenly.
How much is 25 mm of rain in inches?
About 0.98 inches, so call it an inch. A solid day of steady rain. 25.4 mm would be exactly one inch.
Does the calculation happen on your servers?
No. It’s plain JavaScript running in your browser. Nothing about your input is sent anywhere, and it keeps working even if you go offline after loading.