Formula
in to mm conversion formula
Use this relationship for a direct conversion:
mm = in x 25.4
Worked example
2 in = 50.8 mm.
Metric factors and international inch, foot, yard, mile, and nautical mile definitions are exact.
Length conversion
Convert Inch to Millimeter
1 inch (in) equals 25.4 millimeter (mm). Enter any value below to convert from in to mm.
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1 in = 25.4 mm
All Length units
From 1 in| Unit | Value |
|---|---|
| Meter m | 0.0254 |
| Kilometer km | 0.0000254 |
| Centimeter cm | 2.54 |
| Millimeter mm | 25.4 |
| Micrometer μm | 25,400 |
| Nanometer nm | 25,399,999.9999999963 |
| Inch in | 1 |
| Foot ft | 0.0833333333 |
| Yard yd | 0.0277777778 |
| Mile mi | 0.0000157828 |
| Nautical mile nmi | 0.0000137149 |
| Light-year ly | 2.6847821184e-18 |
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Quick reference
Inch to Millimeter table
| Inch (in) | Millimeter (mm) |
|---|---|
| 0.01 | 0.254 |
| 0.1 | 2.54 |
| 1 | 25.4 |
| 2 | 50.8 |
| 5 | 127 |
| 10 | 254 |
| 25 | 635 |
| 50 | 1,270 |
| 100 | 2,540 |
| 1,000 | 25,400 |
From unit
About the inch
Exactly 25.4 millimeters by international agreement.
Symbol: in
To unit
About the millimeter
One thousandth of a meter.
Symbol: mm
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Conversion standard
Definitions are checked against NIST SP 811: Guide for the Use of the SI. Calculations use full internal precision before display rounding.
View the complete length converterQuestions
in to mm FAQ
How do you convert inch to millimeter?
Use the formula mm = in x 25.4. 1 inch (in) equals 25.4 millimeter (mm).
Is the in to mm conversion exact?
Both unit definitions use exact factors. Only the displayed decimal may be rounded.