Convert Millimeters (mm) to Inches (in)
Convert millimetres (mm) to inches (in): 1 inch = 25.4 mm exactly, so divide millimetres by 25.4. Useful for screen sizes, hardware, woodworking and engineering drawings.
Formula
1 mm = 0.03937 in
To convert mm to in, divide the value by 25.4.
Conversion Table
| Millimeters (mm) | Inches (in) |
|---|---|
| 0.01 mm | 0.0004 in |
| 0.1 mm | 0.0039 in |
| 0.5 mm | 0.0197 in |
| 1 mm | 0.0394 in |
| 2 mm | 0.0787 in |
| 3 mm | 0.1181 in |
| 5 mm | 0.1969 in |
| 10 mm | 0.3937 in |
| 15 mm | 0.5906 in |
| 20 mm | 0.7874 in |
| 25 mm | 0.9843 in |
| 50 mm | 1.9685 in |
| 100 mm | 3.937 in |
| 250 mm | 9.8425 in |
| 500 mm | 19.685 in |
| 1000 mm | 39.3701 in |
| 2500 mm | 98.4252 in |
| 5000 mm | 196.8504 in |
| 10000 mm | 393.7008 in |
| 50000 mm | 1968.5039 in |
Common mm to in Examples
- 1 mm = 0.0394 in
- 5 mm = 0.1969 in
- 10 mm = 0.3937 in
- 25 mm = 0.9843 in
- 50 mm = 1.9685 in
- 100 mm = 3.937 in
- 500 mm = 19.685 in
- 1000 mm = 39.3701 in
About mm to in
The inch is defined as exactly 25.4 mm, so mm divided by 25.4 gives inches — 100 mm is about 3.94 in. The relationship is exact, not an approximation.
This conversion is everywhere in making and building: bolt and pipe sizes, plywood thickness, phone and TV dimensions, and drawings that mix metric and imperial. Many tools and fasteners come in both systems, so converting mm to inches avoids costly mistakes.
Frequently Asked Questions
Why is the conversion factor between mm and in 0.03937?
It comes from the official definitions of both Length units, which are anchored to internationally agreed reference standards.
What is a quick way to estimate mm to in?
Round 0.03937 to one or two significant digits and multiply mentally. Use the exact factor when accuracy matters.
How do I convert mm to in by hand?
Take the value in mm and divide the value by 25.4. The result is the same value expressed in in.
Which industries rely on mm to in conversions?
Logistics, manufacturing, scientific research, and international commerce all routinely move between mm and in.
Is the conversion from mm to in exact?
The ratio 0.03937 is defined to high precision and is exact for most practical purposes. Rounding only matters when many decimal places are needed.
What are common uses for converting mm to in?
Typical scenarios include travel, trade, engineering, science, and any situation where data is reported in mm but needed in in.