How do I convert mm to inches?
Type either value and the other one updates as you type.
- Inches (in)
- 0.03937
1 mm = 0.03937 in.
- Nearest 1/64 inch
- 3/64
Inches (in): 0.03937. 1 mm = 0.03937 in.
Inches (in) by millimeters (mm)
How to calculate
Converts millimeters (mm) to inches (in) and back, with the exact unit definitions.
Example with the default inputs (Millimeters (mm) 1): 1 mm = 0.03937 in.
Formula: in = mm × 0.0393700787402 (the same as mm ÷ 25.4)
- 1 millimeter = 0.0393700787402 inches, from the exact definitions in NIST SP 811.
- The answer shows at most 6 decimal places; the calculation keeps full precision.
Worked examples
Each example is checked against the calculator on every build.
- Millimeters (mm) 1 gives Inches (in) 0.03937.Source: exact unit definitions in NIST SP 811 (2008), Appendix B.8
- Millimeters (mm) 25 gives Inches (in) 0.984252.Source: exact unit definitions in NIST SP 811 (2008), Appendix B.8
- Inches (in) 0.984252 gives Millimeters (mm) 25.Source: exact unit definitions in NIST SP 811 (2008), Appendix B.8
Other questions people ask
How many inches are in a millimeter?
1 millimeter is 0.03937 inches, from the exact unit definitions (NIST SP 811).
How do I convert mm to inches?
Multiply by 0.03937: in = mm × 0.0393700787402 (the same as mm ÷ 25.4). For example, 1 mm × 0.03937 = 0.03937 in.
How do I convert inches back to mm?
Multiply by 25.4, or type the inches into the second box and the converter works it out. 1 inch is 25.4 millimeters.