📏 Length
inches to millimeters Converter
Convert inches to millimeters instantly. Includes a reference table and formula.
Quick answer: To convert inches to millimeters, multiply by 25.4. For example, 1 inches = 25.4 millimeters. Use the calculator below for any value.
inches to millimeters
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Common conversions
| inches | millimeters |
|---|
Formula:
How to convert inches to millimeters
1
Enter your value
Type the number of inches you want to convert into the left box. The result in millimeters appears instantly in the right box. You can also type into the right box to convert in the other direction.
2
Use the swap button
Click the ⇄ Swap button to reverse the conversion — millimeters to inches. Your current value carries across so you don't have to re-enter anything.
3
About inches and millimeters
inches and millimeters are both length measurements. Use this converter to switch between them instantly.
💡 Did you know?
1 inch = 25.4 mm exactly. The factor has been internationally agreed since 1959 and is used everywhere from carpentry to aircraft manufacturing.
📊 Common conversions at a glance
| inches | millimeters |
|---|---|
| 0.25 | 6.35 |
| 0.5 | 12.7 |
| 1 | 25.4 |
| 2 | 50.8 |
| 3 | 76.2 |
| 4 | 101.6 |
Reviewed for 2026. inches ↔ millimeters conversion factor verified against published reference data. Built by a UK-based qualified primary teacher and FA Level 2 coach as part of 247QuickTools' free utility-tools project.