Millimeters to Inches Converter
Convert mm to inches instantly. Free online mm to in calculator—divide by 25.4. For 3D printing, bolts, and screen specs.
How to Convert Millimeter to Inch
To convert millimeters to inches, multiply the number of millimeters by 0.03937. One millimeter equals approximately 0.03937 inches, making this conversion essential for precise measurements between metric and imperial systems.
Conversion Formula:
value * 0.0393700787Conversion Examples
Example: 25.4 mm to inches
- 25.4 ÷ 25.4 = 1 in
25.4 mm = 1 inch
Exact definition.
Example: 10 mm to inches
- 10 ÷ 25.4 ≈ 0.394 in
10 mm ≈ 0.394 inches
Common bolt/shim size.
Conversion Chart
| Millimeter | Inch |
|---|---|
| 1 | 0.0394 |
| 10 | 0.3937 |
| 25.4 | 1 |
| 50 | 1.9685 |
| 100 | 3.937 |
| 250 | 9.8425 |
| 500 | 19.685 |
| 1000 | 39.37 |
Conversion Formula
The formula to convert millimeters to inches is:
millimeters × 0.03937 = inches
Mathematically, you can write this as:
millimeters × 0.03937 inches/millimeter = inches
Since 1 inch equals exactly 25.4 millimeters, dividing by 25.4 (or multiplying by 0.03937) converts millimeters to inches using the standard international conversion factor.
Quick Conversion Tip
Quick conversion: Divide millimeters by 25.4 to get inches, or multiply by 0.0394 (approximately). For example, 25.4 mm = 1 in, 100 mm ≈ 3.94 in, 250 mm ≈ 9.84 in. Remember that 1 inch equals exactly 25.4 millimeters.
Unit Definitions
Millimeter (mm)
A millimeter is a metric unit of length equal to one-thousandth of a meter (1/1000 m). It is the smallest common metric unit for length measurements and is widely used in engineering, manufacturing, and precision measurements.
1 millimeter = 0.1 centimeters = 0.01 decimeters = 0.001 meters = 0.000001 kilometers = 0.0393701 inches
Inch (in)
An inch is an imperial unit of length equal to 1/12 of a foot or exactly 2.54 centimeters. It is commonly used in the United States and United Kingdom for measuring length, height, and dimensions.
1 inch = 2.54 centimeters = 25.4 millimeters = 0.083333 feet = 0.027778 yards
Common Use Cases
- 3D printing and machining tolerances.
- Wrench and drill bit sizing.
- Product dimensions on import packaging.
- Science lab ruler conversions.
Understanding the Conversion
Millimeters to inches: divide by 25.4 (exact). Essential for metric hardware specs, tire tread depth, and engineering drawings in inches.
1 inch = 25.4 mm exactly.
3D printing and machining tolerances. The table and FAQ on this page walk through the factor if you need it.
FAQs
How many inches in a millimeter?
1 mm ≈ 0.03937 inches (divide by 25.4).
How do I convert mm to inches?
Divide millimeters by 25.4.
What is 50 mm in inches?
50 ÷ 25.4 ≈ 1.97 inches.