Inch fraction to decimal chart
Every sixteenth of an inch as a decimal and in millimetres. The conversion table for reading a tape into a calculator and back again.
| Fraction | Decimal | Millimetres | Thirty-seconds | Sixty-fourths |
|---|---|---|---|---|
| 1/16" | 0.0625 | 1.59 | 2/32 | 4/64 |
| 1/8" | 0.1250 | 3.17 | 4/32 | 8/64 |
| 3/16" | 0.1875 | 4.76 | 6/32 | 12/64 |
| 1/4" | 0.2500 | 6.35 | 8/32 | 16/64 |
| 5/16" | 0.3125 | 7.94 | 10/32 | 20/64 |
| 3/8" | 0.3750 | 9.52 | 12/32 | 24/64 |
| 7/16" | 0.4375 | 11.11 | 14/32 | 28/64 |
| 1/2" | 0.5000 | 12.70 | 16/32 | 32/64 |
| 9/16" | 0.5625 | 14.29 | 18/32 | 36/64 |
| 5/8" | 0.6250 | 15.88 | 20/32 | 40/64 |
| 11/16" | 0.6875 | 17.46 | 22/32 | 44/64 |
| 3/4" | 0.7500 | 19.05 | 24/32 | 48/64 |
| 13/16" | 0.8125 | 20.64 | 26/32 | 52/64 |
| 7/8" | 0.8750 | 22.22 | 28/32 | 56/64 |
| 15/16" | 0.9375 | 23.81 | 30/32 | 60/64 |
| 1" | 1.0000 | 25.40 | 32/32 | 64/64 |
Reading it
- A tape is marked in sixteenths; a calculator wants decimals. This is the table that gets taped inside the lid of a toolbox for exactly that reason.
- The inch is defined as exactly 25.4 mm, so the millimetre column is exact arithmetic rather than an approximation.
- Thirty-seconds and sixty-fourths are the same fraction written finer — useful when a drill index or a feeler gauge is marked in them.
For the case this table does not cover
- Inch fraction calculator
Add or subtract two measurements written the way a tape shows them, read to the nearest sixteenth, thirty-second or sixty-fourth.
- Board cut calculator
How many pieces of one length come out of a board of another, with the kerf charged between cuts and the leftover shown.