Inch to Millimeter Converter
1 in = 25.4 mm — convert instantly with formula and table.
Type a value above and it converts instantly — no button to press, no page reload, and the math runs entirely in your browser.
Quick answer: one inch equals 25.4 millimeters. So to convert inches to millimeters, multiply by 25.4.
How to convert inches to millimeters
millimeters = inches × 25.4
The inch has been defined as exactly 2.54 centimeters since 1959. Screen sizes worldwide are still quoted in inches, making it one of the most-converted units on the internet.
The millimeter is one thousandth of a meter and the workhorse of precision measurement — engineering drawings, 3D printing tolerances and rainfall totals are all quoted in millimeters.
Inch to Millimeter conversion table
| Inch (in) | Millimeter (mm) |
|---|---|
| 0.01 in | 0.254 mm |
| 0.1 in | 2.54 mm |
| 0.25 in | 6.35 mm |
| 0.4 in | 10.16 mm |
| 0.75 in | 19.05 mm |
| 1.25 in | 31.75 mm |
| 1.75 in | 44.45 mm |
| 2.5 in | 63.5 mm |
| 3.5 in | 88.9 mm |
| 4.5 in | 114.3 mm |
| 6 in | 152.4 mm |
| 8 in | 203.2 mm |
| 10 in | 254 mm |
| 12 in | 304.8 mm |
| 14 in | 355.6 mm |
| 16 in | 406.4 mm |
| 18 in | 457.2 mm |
| 20 in | 508 mm |
| 24 in | 609.6 mm |
| 26 in | 660.4 mm |
| 30 in | 762 mm |
| 35 in | 889 mm |
| 45 in | 1,143 mm |
| 55 in | 1,397 mm |
| 65 in | 1,651 mm |
| 75 in | 1,905 mm |
| 85 in | 2,159 mm |
| 95 in | 2,413 mm |
| 110 in | 2,794 mm |
| 125 in | 3,175 mm |
| 175 in | 4,445 mm |
| 250 in | 6,350 mm |
| 350 in | 8,890 mm |
| 450 in | 11,430 mm |
| 600 in | 15,240 mm |
| 750 in | 19,050 mm |
| 900 in | 22,860 mm |
| 1,500 in | 38,100 mm |
| 2,500 in | 63,500 mm |
| 10,000 in | 254,000 mm |
Need the opposite direction? Use the Millimeter to Inch converter, or read our complete guide to length conversions for every formula in one place.
Frequently asked questions
How many millimeters are in one inch?
One inch equals 25.4 millimeters. Multiply any inch value by 25.4 to get millimeters.
What is 10 inches in millimeters?
10 inches equal 254 millimeters (10 × 25.4).
Is the inch to millimeter conversion exact?
The conversion factor used here (25.4) is based on the internationally agreed definitions of both units, so results are exact up to rounding of the final decimal places.
Is my data stored when I use this converter?
No. The conversion runs entirely in your browser with JavaScript — nothing you type is sent to a server, logged or stored.