Millimetres to Inches
1 millimetre = 0.03937 inches · 1 in = 25.4 mm
1 millimetre = 0.03937 inches
How it’s calculated
in = mm ÷ 25.4
- Divide the value in millimetres by 25.4.
- Equivalently, multiply by 0.03937007874.
- 1 mm = 0.03937007874 in · 1 in = 25.4 mm
Show worked solutionFactor, unit cancellation and rounding, step by step
Find the conversion factor
By definition 1 mm = 0.001 m and 1 in = 0.0254 m, so 1 in = 25.4 mm. Source: BIPM SI Brochure (9th ed.); NIST SP 811 / Handbook 44.
Multiply by the factor written as a fraction
Put mm in the denominator so it cancels, leaving in.
Calculate (unrounded)
Round the answer
Rounded to 5 significant figures.
Answer: 0.03937 in
1 mm in other units
Batch convert mm → in
- 1 mm = 0.03937 in
- 5 mm = 0.19685 in
- 10 mm = 0.3937 in
- 25 mm = 0.98425 in
Quick examples
- 1 millimetre = 0.03937 inches
- 5 millimetres = 0.19685 inches
- 10 millimetres = 0.3937 inches
- 25 millimetres = 0.98425 inches
- 100 millimetres = 3.937 inches
About these units
Millimetre (mm)
SI (metric)
Exactly 1/1 000 of a metre.
1 mm = 0.001 m
Source: BIPM SI Brochure (9th ed.)
Inch (in)
US & imperial (identical)
Exactly 2.54 cm (international inch, 1959).
1 in = 0.0254 m
Source: NIST SP 811 / Handbook 44
Millimetres to inches conversion table
| Millimetres (mm) | Inches (in) |
|---|---|
| 0.1 mm | 0.003937 in |
| 0.5 mm | 0.019685 in |
| 1 mm | 0.03937 in |
| 2 mm | 0.07874 in |
| 3 mm | 0.11811 in |
| 4 mm | 0.15748 in |
| 5 mm | 0.19685 in |
| 6 mm | 0.23622 in |
| 7 mm | 0.27559 in |
| 8 mm | 0.31496 in |
| 9 mm | 0.35433 in |
| 10 mm | 0.3937 in |
| 15 mm | 0.59055 in |
| 20 mm | 0.7874 in |
| 25 mm | 0.98425 in |
| 30 mm | 1.1811 in |
| 40 mm | 1.5748 in |
| 50 mm | 1.9685 in |
| 75 mm | 2.9528 in |
| 100 mm | 3.937 in |
| 250 mm | 9.8425 in |
| 500 mm | 19.685 in |
| 1,000 mm | 39.37 in |
Related conversions
Frequently asked questions
How do I convert millimetres to inches?
Use in = mm ÷ 25.4. Divide the value in millimetres by 25.4.
How many inches are in 1 millimetre?
1 millimetre (mm) equals 0.03937 inches (in); more precisely 0.03937007874.
How many millimetres are in 1 inch?
1 inch (in) equals 25.4 millimetres (mm).
What is 10 mm in in?
10 millimetres = 0.3937 inches.
What is a millimetre?
Exactly 1/1 000 of a metre.
What is a inch?
Exactly 2.54 cm (international inch, 1959).
Formula: in = mm ÷ 25.4. Factors last reviewed 2026-10-27.