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.
Inches → Millimeters
Enter a value in Inches•1 Inches = 25.4 Millimeters
Inches
Decimals supported.
Result
Millimeters
—
Enter a value to convert Inches to Millimeters.
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.