MM to Inches Converter
Convert millimetres to inches instantly. 1 mm = 0.0393701 in, with a table covering centimetres, feet and metres.
1 Millimetre (mm) =
0.03937 in
Inch (in)
Centimetre (cm)0.1
Metre (m)0.001
Kilometre (km)0.000001
Foot (ft)0.003281
Yard (yd)0.001094
Mile (mi)0.000000621
Nautical mile0.00000054
All other units in this category are shown above for the same input value.
About the MM to Inches Converter
Enter a measurement in millimetres to read it in inches. Millimetres are the working unit on most engineering drawings and fastener specs, so the table also shows centimetres, feet and metres for cross-checking.
Formula
One inch is exactly 25.4 millimetres, so millimetres divided by 25.4 gives inches. The reciprocal, 0.0393700787, works as a multiplier. As with centimetres the relationship is exact by definition, not rounded.
MM to Inches conversion table
| Millimetre (mm) | Inch (in) | Inches (nearest 1/32) |
|---|---|---|
| 1 | 0.03937 | 1/32″ |
| 2 | 0.07874 | 3/32″ |
| 3 | 0.11811 | 1/8″ |
| 4 | 0.15748 | 5/32″ |
| 5 | 0.19685 | 3/16″ |
| 6 | 0.23622 | 1/4″ |
| 7 | 0.27559 | 9/32″ |
| 8 | 0.31496 | 5/16″ |
| 9 | 0.35433 | 11/32″ |
| 10 | 0.3937 | 13/32″ |
| 15 | 0.59055 | 19/32″ |
| 20 | 0.7874 | 25/32″ |
| 25 | 0.98425 | 31/32″ |
| 30 | 1.1811 | 1 3/16″ |
| 40 | 1.5748 | 1 9/16″ |
| 50 | 1.9685 | 1 31/32″ |
| 60 | 2.3622 | 2 3/8″ |
| 70 | 2.7559 | 2 3/4″ |
| 80 | 3.1496 | 3 5/32″ |
| 90 | 3.5433 | 3 17/32″ |
| 100 | 3.937 | 3 15/16″ |
| 250 | 9.8425 | 9 27/32″ |
| 500 | 19.685 | 19 11/16″ |
| 1,000 | 39.3701 | 39 3/8″ |
Frequently Asked Questions
0.03937 inches, or roughly one twenty-fifth. Twenty-five millimetres is 0.984 inches, just under one inch.
Exactly one inch. That figure is the definition of the inch, which is why it turns up in so many conversion tables.
Divide by 25.4 to get decimal inches, then multiply the decimal part by 16 for sixteenths. 10 mm is 0.3937 in, and 0.3937 × 16 is 6.3, so a shade over 6/16 — that is 3/8 of an inch.
Neither unit is inherently more precise; precision comes from how many digits you keep. Millimetres just avoid fractions, which is why machining drawings favour them.
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