Seldons
mm to inches
1 millimeter = 0.0393701 inches.
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How do you convert millimeters to inches?
Use this formula. It is exact — these units are defined by international agreement, not measured.
in = mm ÷ 25.4
Example: 10 mm × 0.0393700787 = 0.393701 in.
mm to inches conversion table
Common values, rounded to six significant figures.
| mm | in |
|---|---|
| 1 mm | 0.0393701 in |
| 2 mm | 0.0787402 in |
| 3 mm | 0.11811 in |
| 5 mm | 0.19685 in |
| 6 mm | 0.23622 in |
| 8 mm | 0.314961 in |
| 10 mm | 0.393701 in |
| 12 mm | 0.472441 in |
| 15 mm | 0.590551 in |
| 20 mm | 0.787402 in |
| 25 mm | 0.984252 in |
| 30 mm | 1.1811 in |
| 50 mm | 1.9685 in |
| 75 mm | 2.95276 in |
| 100 mm | 3.93701 in |
| 150 mm | 5.90551 in |
| 200 mm | 7.87402 in |
Millimeters show up wherever precision matters and inches do not divide cleanly — drill bits, screw lengths, sheet thickness, phone screen bezels, 3D printer nozzles. The relationship is exact by definition: an inch has been defined as 25.4 mm since the 1959 international yard and pound agreement, so this is not an approximation you need to worry about rounding.
Values worth remembering
These come up often enough that knowing them saves a lookup.
- 25.4 mm = 1 inexactly one inch
- 210 mm = 8.26772 inA4 paper width
- 297 mm = 11.6929 inA4 paper height
Questions people ask
How many inches is 1 millimeter?
1 millimeter is 0.0393701 inches.
How many millimeters is 1 inch?
1 inch is 25.4 millimeters.
How do you convert millimeters to inches in your head?
Use × 0. That lands within a percent or so of the exact figure, which is close enough for packing, shipping estimates and shopping — use the calculator when the number has to be right.
Is the millimeter to inch conversion exact?
Yes. The relationship is exact by international agreement, so 0.0393700787 is a definition rather than a measurement. Rounding in the answer comes from display, not from the conversion.