Inches to Millimeters (in to mm)
Free online inch to millimeter converter. Type a value, get an instant exact result — plus the formula, a ready-made conversion table, and reverse conversion.
LENGTH CONVERTER — INSTANT RESULT
Formula: multiply the inch value by 25.4 — i.e. mm = in × 25.4
Quick check: 1 in = 25.4 mm
Quick check: 1 in = 25.4 mm
Inches to Millimeters conversion table
| Inches (in) | Millimeters (mm) |
|---|---|
| 1 in | 25.4 mm |
| 2 in | 50.8 mm |
| 3 in | 76.2 mm |
| 4 in | 101.6 mm |
| 5 in | 127 mm |
| 6 in | 152.4 mm |
| 7 in | 177.8 mm |
| 8 in | 203.2 mm |
| 9 in | 228.6 mm |
| 10 in | 254 mm |
| 15 in | 381 mm |
| 20 in | 508 mm |
| 25 in | 635 mm |
| 30 in | 762 mm |
| 40 in | 1,016 mm |
| 50 in | 1,270 mm |
| 75 in | 1,905 mm |
| 100 in | 2,540 mm |
| 250 in | 6,350 mm |
| 500 in | 12,700 mm |
| 1,000 in | 25,400 mm |
How to convert inches to millimeters
To convert inches to millimeters, multiply the amount in inches by 25.4. For example, 10 in = 254 mm. To convert in the other direction, divide by the same factor, or use the ⇄ swap button above.
Convert between metric and imperial/US customary length units, plus nautical, astronomical and survey units. The meter is the SI base unit of length; all factors below are exact definitions where a legal definition exists.
Frequently asked questions
How many millimeters are in one inch?
One inch is exactly 25.4 millimeters.
How do I convert in to mm?
Multiply the in value by 25.4 to get mm. The converter at the top of this page does this automatically and works in both directions.
How much is 100 inches in millimeters?
100 inches equals 2,540 millimeters.