Fraction, decimal & mm chart
| Fraction | Decimal (in) | Millimetres |
|---|---|---|
| 1/16" | 0.0625 | 1.59 |
| 1/8" | 0.125 | 3.17 |
| 3/16" | 0.1875 | 4.76 |
| 1/4" | 0.25 | 6.35 |
| 5/16" | 0.3125 | 7.94 |
| 3/8" | 0.375 | 9.52 |
| 7/16" | 0.4375 | 11.11 |
| 1/2" | 0.5 | 12.70 |
| 9/16" | 0.5625 | 14.29 |
| 5/8" | 0.625 | 15.88 |
| 11/16" | 0.6875 | 17.46 |
| 3/4" | 0.75 | 19.05 |
| 13/16" | 0.8125 | 20.64 |
| 7/8" | 0.875 | 22.22 |
| 15/16" | 0.9375 | 23.81 |
| 1/1" | 1 | 25.40 |
Decimal = the fraction divided out (top ÷ bottom). Millimetres = decimal inches × 25.4, since one inch is exactly 25.4 mm. Every figure here is arithmetic you can reproduce — nothing is looked up.
Practise moving between these on the fraction/decimal drill and the conversion drill.
Learn one thing a week
Now and then a new diagram, drill, or reference sheet goes up. Leave your email for a short heads-up when it does — no spam, no selling it on, one click to leave.