Millimeters to Inches Converter
Use our millimeters to inches converter to calculate mm to inch instantly. This mm to in converter includes the mm to inch formula, examples (including diameter), and a quick mm to in conversion chart.
What is Millimeters to Inches Conversion?
Millimeters (mm) and inches (in) are both units of length used in different measurement systems. Millimeters are part of the metric system, while inches are part of the US customary and imperial systems. A millimeter to inch converter helps you switch between these units quickly.
If you’re searching convert millimeters to inches calculator, you may be working with product dimensions, engineering drawings, tools, or measurements like convert mm to inches diameter (for pipes, bolts, drill bits, and circles). The conversion is the same: just convert the length value from mm to inches.
The key relationship is that 1 inch equals 25.4 millimeters. That answers questions like how many millimeters to one inch and how much mm in 1 inch.
Millimeters to Inches Formula
To convert mm to in, divide millimeters by 25.4. For the reverse conversion, multiply inches by 25.4. This is the standard calculate mm to inch formula.
This is the standard mm to inch converter equation (exact: 1 in = 25.4 mm).
Use this if you need the reverse conversion.
So there are 25.4 millimeters in 1 inch.
So 50 mm is about 1.97 inches.
Diameter conversion uses the same mm to in formula—just convert the diameter value.
If you need mm to fraction of inch, convert to inches first, then round to a common fraction (like 1/64).
mm to in conversion chart
Quick reference values for common conversions (millimeters to inches).
| mm | in |
|---|---|
| 1 | 0.0394 |
| 2 | 0.0787 |
| 5 | 0.1969 |
| 10 | 0.3937 |
| 12 | 0.4724 |
| 15 | 0.5906 |
| 20 | 0.7874 |
| 25.4 | 1 |
| 30 | 1.1811 |
| 50 | 1.9685 |
| 100 | 3.9370 |
How to Convert mm to in
- 1
Enter the measurement in millimeters (mm).
- 2
Divide the mm value by 25.4.
- 3
Read the result in inches (in).
- 4
To convert inches back to mm, multiply inches by 25.4.
Frequently Asked Questions
Divide millimeters by 25.4. The formula is in = mm ÷ 25.4.
There are exactly 25.4 mm in 1 inch.
Yes—this millimeters to inches converter performs the standard mm to in conversion instantly.
Feet are a different unit. Convert mm to inches (÷ 25.4) and then divide inches by 12 to get feet.
Convert mm to inches first, then round the decimal inches to a common fraction (often 1/64 for tools and hardware).
The standard mm to inch converter formula is in = mm ÷ 25.4.