3 mm to Inches
Answer
0.11811 in
3 mm = 0.11811 in ≈ 1/8 in
3 millimeters equals 0.11811 inches, which rounds to almost exactly 1/8 inch (0.125 in). It is best known as the nominal shank diameter of an M3 machine screw, one of the most common metric fasteners used in electronics, eyeglass hinges, and 3D-printer frames. It also sits close to the 3.175 mm mark that equals a true 1/8 inch drill bit, so the two sizes are easy to mix up in a mixed metric and imperial toolbox.
Try another mm value
Decimal inches
0.11811"
Nearest 1/64
1/8"
Centimeters
0.3 cm
Related values
| Value | Result |
|---|---|
| Decimal inches | 0.11811 in |
| Nearest 1/16 in | 1/8 in |
| Nearest 1/32 in | 1/8 in |
| Nearest 1/64 in | 1/8 in |
| Centimeters | 0.3 cm |
How the conversion works
- Divide by 25.4. Millimeters convert to inches by dividing by 25.4, since one inch is defined as exactly 25.4 mm under the international agreement adopted in 1959. For 3 mm, that is 3 ÷ 25.4 = 0.11811 inches, the number a digital caliper shows when switched to inch mode.
- Round to a fraction. To express 0.11811 in as a fraction, multiply it by 64 to get 7.559, then round to the nearest whole number, 8. That gives 8/64, an unreduced fraction at this stage.
- Simplify and read the answer. Divide both the numerator and denominator of 8/64 by their greatest common divisor, 8, to reach 1/8 in. That is the fraction most tape measures and drill indexes show for a 3 mm measurement.
Frequently Asked Questions
3 mm equals 0.11811 inches. Rounded to a usable fraction, that is 1/8 in (0.125 in), only about 0.007 in larger than the exact decimal value, which is close enough for most hardware and drilling work.
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