Convert millimeters to inches (fraction) instantly. Enter a value below, or use the formula and reference table further down the page.
In practice
Millimetres to the nearest inch fraction is the reverse of a common workshop problem: you have a metric measurement but a tape measure or drill set marked in sixteenths and thirty-seconds. The conversion divides by 25.4 and then rounds to the closest fraction, which means the result is nearly always a close approximation, not an exact match. A 10 mm bolt, for example, is about 25/64 inch, and a 6 mm bit is a little under 1/4 inch. When fit matters, choose the next size up or down deliberately rather than relying on the rounded figure.
How to convert millimeters to inches (fraction)
Multiply the value by 0.03937007874.
in = mm × 0.03937007874Example: 10 mm = 0.3937 in.
Millimeters to Inches (fraction) conversion table
| Millimeters (mm) | Inches (fraction) (in) |
|---|---|
| 1 mm | 0.0394 in |
| 2 mm | 0.0787 in |
| 3 mm | 0.1181 in |
| 4 mm | 0.1575 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 |
Frequently asked questions
How many inches (fraction) is 1 millimeter?
1 millimeter equals 0.0394 inches (fraction).
What is the formula to convert mm to in?
To convert mm to in, multiply the value by 0.03937007874. The full formula is: in = mm × 0.03937007874.
How do I convert inches (fraction) back to millimeters?
Use the same calculator above and type your value into the inches (fraction) field instead — it converts in both directions. Or use the reverse formula: mm = in ÷ 0.03937007874.
Is the mm to in conversion exact?
The conversion factor used here (0.03937007874) is the standard internationally defined value. Results on this page are rounded to four decimal places for readability.