Instant conversion
Inches To Mm Converter
1 inch = 25.4 millimeters. Multiply inches by 25.4.
12.7 mm
Common in to mm conversions
| in | mm |
|---|---|
| 0.5 | 12.7 |
| 1 | 25.4 |
| 2 | 50.8 |
| 3 | 76.2 |
| 5 | 127 |
| 10 | 254 |
| 20 | 508 |
| 50 | 1270 |
| 100 | 2540 |
| 200 | 5080 |
| 500 | 12700 |
| 1000 | 25400 |
How this conversion works
1 inch = 25.4 millimeters. Multiply inches by 25.4.
Privacy: Conversions run in this browser. Nothing you type is uploaded.
What you are converting
Inch
An inch is 1/12 of a foot, exactly 25.4 mm. Real-world anchor: a US quarter is about 1 inch wide.
Millimeter
A millimeter is 1/1,000 of a meter. Real-world anchor: a standard paper clip wire is about 1 mm thick.
Why convert and when you would use this
Reverse hardware conversion — US tools measured in inches used on metric parts.
Rounding and accuracy
Use 2–4 decimal places for everyday tasks; keep more for engineering or lab precision.
Frequently asked questions
How do you convert in to mm?
1 inch = 25.4 millimeters. Multiply inches by 25.4.
What is 1 in in mm?
1 in equals 25.4 mm.
How do you convert back from mm to in?
Use the related mm to in page.