Inches to Millimeters
Convert inches to millimeters instantly. The formula is mm = in × 25.4, and the reference table below covers the values people look up most.
1 in equals
25.400 mm
mm = in × 25.4
Formula
mm = in × 25.4
Inches to Millimeters table
| Inches | Millimeters |
|---|---|
| 1 in | 25.400 mm |
| 2 in | 50.800 mm |
| 3 in | 76.200 mm |
| 5 in | 127.000 mm |
| 10 in | 254.000 mm |
| 15 in | 381.000 mm |
| 20 in | 508.000 mm |
| 25 in | 635.000 mm |
| 30 in | 762.000 mm |
| 50 in | 1,270.000 mm |
| 100 in | 2,540.000 mm |
Frequently asked questions
How many millimeters are in a inche?
One inche equals 25.400 millimeters. The conversion is a single multiplication, so 10 in is 254.000 mm.
What is the formula to convert inches to millimeters?
mm = in × 25.4. Enter any value above and the result updates as you type, with no rounding until the final display.
How do I convert millimeters back to inches?
Use the reverse conversion: divide instead of multiplying, or open the millimeters to inches page for the same tool the other way round.
Is this inches to millimeters conversion exact?
The underlying factor is the internationally defined one, so the only rounding happens when the result is displayed. The table below shows values rounded to 3 decimal places.