10 mm to Inches
Answer
0.393701 in
10 mm = 0.393701 in ≈ 25/64 in
10 millimeters equals 0.393701 inches, close to but not quite 3/8 inch (0.375 in). It is best known as the 10mm socket, the wrench size mechanics reach for constantly on bolt heads and nuts, and it is also the across-flats measurement of a standard M6 nut. At 1/64 inch precision the exact fraction is 25/64 in, a hair larger than the more familiar 3/8 in rounding used at 1/16 inch.
Try another mm value
Decimal inches
0.393701"
Nearest 1/64
25/64"
Centimeters
1 cm
Related values
| Value | Result |
|---|---|
| Decimal inches | 0.393701 in |
| Nearest 1/16 in | 3/8 in |
| Nearest 1/32 in | 13/32 in |
| Nearest 1/64 in | 25/64 in |
| Centimeters | 1 cm |
How the conversion works
- Divide by 25.4. Because one inch is defined as exactly 25.4 mm, dividing by 25.4 turns any millimeter reading into inches. For 10 mm: 10 ÷ 25.4 = 0.393701 inches, a decimal that keeps repeating at higher places since 10/25.4 does not terminate.
- Round to a fraction. Multiply 0.393701 by 64 to get 25.197, then round to the nearest whole number, 25. That produces the fraction 25/64 before checking whether it can be reduced.
- Simplify and read the answer. 25 and 64 share no common factor other than 1, so 25/64 in is already fully simplified. At the coarser 1/16 in precision the same measurement rounds instead to 3/8 in, which is why both numbers appear on different charts.
Frequently Asked Questions
10 mm equals 0.393701 inches. Rounded to 1/16 in precision that is 3/8 in, and at the finer 1/64 in precision it is 25/64 in, a difference of about 0.008 in between the two roundings.
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