Inches to Millimeters Calculator
Need to match a US part to a metric blueprint? Instantly convert inches to millimeters (in to mm) for flawless engineering, hardware sizing, and 3D printing specs.
Converting the other way? Use the Millimeters to Inches Calculator.
How to convert Inches to Millimeters?
How many Millimeters are in a Inches? The key relationship is:
- 1 Inch = 25.4 Millimeters
- 1 Millimeter = 0.0393701 Inches
To convert Inches to Millimeters, multiply the value by 25.4.
Formula: Millimeters = Inches × 25.4
Step-by-Step Calculation
- 1Take the number of Inches you want to convert (e.g., 4).
- 2Multiply that value by 25.4.
- 3The result is the value in Millimeters. (Example: 4 × 25.4 = 101.6 Millimeters).
How to use this converter?
Enter inches and instantly get millimeters—useful for engineering, tools, and precise measurements.
Common Inches to Millimeters Conversions
| Inches Input | Millimeters Result |
|---|---|
| 0.5 Inch | 12.7 mm |
| 1 Inch | 25.4 mm |
| 2 Inches | 50.8 mm |
| 3 Inches | 76.2 mm |
| 4 Inches | 101.6 mm |
| 6 Inches | 152.4 mm |
| 8 Inches | 203.2 mm |
| 10 Inches | 254 mm |
| 12 Inches | 304.8 mm |
| 24 Inches | 609.6 mm |
Frequently Asked Questions
Q
How do I convert inches to millimeters?
Multiply inches by 25.4 to get millimeters.
Q
How many mm is 1 inch?
1 inch equals exactly 25.4 mm.
Q
How many mm is 4 inches?
4 inches equals 101.6 mm.
Q
How many mm is 12 inches?
12 inches equals 304.8 mm.
Q
Is the conversion exact?
Yes—because 1 inch is defined as exactly 25.4 millimeters.