100% free · No sign-up · Runs in your browser
Convert inches to millimeters
Instant, accurate in → mm conversion with a live converter, table and formula.
=
1 inche = 25.4 millimeters
1 millimeter = 0.0393701 inches
inches to millimeters table
| inches (in) | millimeters (mm) |
|---|---|
| 0.5 | 12.7 |
| 1 | 25.4 |
| 2 | 50.8 |
| 5 | 127 |
| 10 | 254 |
| 20 | 508 |
| 50 | 1270 |
| 100 | 2540 |
| 500 | 12700 |
| 1000 | 25400 |
Formula
millimeters = inches × 25.4.
Example
10 inches = 254 millimeters.
What is a inche?
An inch (in) is an imperial unit equal to exactly 2.54 cm; 12 inches make a foot.
What is a millimeter?
A millimeter (mm) is one-thousandth of a meter — about the thickness of a credit-card edge.
Real-world reference points
A meter is about one long stride; a foot is a large shoe; an inch is the top joint of a thumb.
| Reference | inches | millimeters |
|---|---|---|
| Credit card width | 3.37 in | 85.6 mm |
| Average adult height | 66.93 in | 1,700 mm |
| Door height | 78.74 in | 2,000 mm |
| Football (soccer) pitch length | 4,134 in | 105,000 mm |
| Marathon distance | 1,660,000 in | 42,200,000 mm |
Mistakes to avoid with length conversions
- Mixing unit systems mid-calculation — convert everything first, then do the math.
- Treating yards and meters as equal: a yard is ~8.6% shorter, which compounds over long distances.
- Rounding centimeters to inches too early when cutting materials — keep one extra decimal until the final cut.
Frequently asked questions
How many millimeters in a inches?+
1 inche = 25.4 millimeters.
How do I convert inches to millimeters?+
Enter the value in the inches box above and the millimeters value appears instantly. You can also type in the millimeters box to convert the other way.
Is this in to mm converter free?+
Yes — it is 100% free, needs no sign-up, and runs entirely in your browser.