3/8 inch to decimal and mm
3/8" = 0.375" = 9.525 mm
3/8 is the standard socket drive size and a common bolt, rod and drywall-anchor size. In decimals it lands on a neat 0.375.
To get the decimal, divide the top number by the bottom: 3 ÷ 8 = 0.375. For millimeters, multiply that by 25.4, which gives 9.525 mm (about 9.5 mm if you're working with a metric ruler).
Nearby sizes in 64ths
| Fraction | Decimal (in) | Millimeters |
|---|---|---|
| 5/16" | 0.312500 | 7.938 mm |
| 21/64" | 0.328125 | 8.334 mm |
| 11/32" | 0.343750 | 8.731 mm |
| 23/64" | 0.359375 | 9.128 mm |
| 3/8" | 0.375000 | 9.525 mm |
| 25/64" | 0.390625 | 9.922 mm |
| 13/32" | 0.406250 | 10.319 mm |
| 27/64" | 0.421875 | 10.716 mm |
| 7/16" | 0.437500 | 11.112 mm |
Need a different value or want to round to 1/32 or 1/64? Use the full converter.