Fraction to decimal chart
Every 64th of an inch from 1/64 to 1 inch, then every 16th to 2 inches and every quarter to 4 inches, as a decimal inch and in millimeters. The decimal is rounded to four places the way a plan or a caliper reads, with the exact value under it when it runs longer. Where a drill bit, a plywood thickness or a board comes in that size, the row links to it.
Printable fraction chart (one page)Convert any size, or round to the nearest 16th
Fractions, decimals and mm
| Fraction | Inch | mm | At this size |
|---|---|---|---|
| 1/64 in | 0.01560.015625 | 0.397 | |
| 1/32 in | 0.03130.03125 | 0.794 | |
| 3/64 in | 0.04690.046875 | 1.191 | |
| 1/16 in | 0.0625 | 1.588 | |
| 5/64 in | 0.07810.078125 | 1.984 | |
| 3/32 in | 0.09380.09375 | 2.381 | |
| 7/64 in | 0.10940.109375 | 2.778 | |
| 1/8 in | 0.1250 | 3.175 | |
| 9/64 in | 0.14060.140625 | 3.572 | |
| 5/32 in | 0.15630.15625 | 3.969 | |
| 11/64 in | 0.17190.171875 | 4.366 | |
| 3/16 in | 0.1875 | 4.763 | |
| 13/64 in | 0.20310.203125 | 5.159 | |
| 7/32 in | 0.21880.21875 | 5.556 | |
| 15/64 in | 0.23440.234375 | 5.953 | |
| 1/4 in | 0.2500 | 6.350 | |
| 17/64 in | 0.26560.265625 | 6.747 | |
| 9/32 in | 0.28130.28125 | 7.144 | |
| 19/64 in | 0.29690.296875 | 7.541 | |
| 5/16 in | 0.3125 | 7.938 | |
| 21/64 in | 0.32810.328125 | 8.334 | |
| 11/32 in | 0.34380.34375 | 8.731 | |
| 23/64 in | 0.35940.359375 | 9.128 | |
| 3/8 in | 0.3750 | 9.525 | |
| 25/64 in | 0.39060.390625 | 9.922 | |
| 13/32 in | 0.40630.40625 | 10.319 | |
| 27/64 in | 0.42190.421875 | 10.716 | |
| 7/16 in | 0.4375 | 11.113 | |
| 29/64 in | 0.45310.453125 | 11.509 | |
| 15/32 in | 0.46880.46875 | 11.906 | |
| 31/64 in | 0.48440.484375 | 12.303 | |
| 1/2 in | 0.5000 | 12.700 | |
| 33/64 in | 0.51560.515625 | 13.097 | |
| 17/32 in | 0.53130.53125 | 13.494 | |
| 35/64 in | 0.54690.546875 | 13.891 | |
| 9/16 in | 0.5625 | 14.288 | |
| 37/64 in | 0.57810.578125 | 14.684 | |
| 19/32 in | 0.59380.59375 | 15.081 | |
| 39/64 in | 0.60940.609375 | 15.478 | |
| 5/8 in | 0.6250 | 15.875 | |
| 41/64 in | 0.64060.640625 | 16.272 | |
| 21/32 in | 0.65630.65625 | 16.669 | |
| 43/64 in | 0.67190.671875 | 17.066 | |
| 11/16 in | 0.6875 | 17.463 | |
| 45/64 in | 0.70310.703125 | 17.859 | |
| 23/32 in | 0.71880.71875 | 18.256 | |
| 47/64 in | 0.73440.734375 | 18.653 | |
| 3/4 in | 0.7500 | 19.050 | |
| 49/64 in | 0.76560.765625 | 19.447 | |
| 25/32 in | 0.78130.78125 | 19.844 | |
| 51/64 in | 0.79690.796875 | 20.241 | |
| 13/16 in | 0.8125 | 20.638 | |
| 53/64 in | 0.82810.828125 | 21.034 | |
| 27/32 in | 0.84380.84375 | 21.431 | |
| 55/64 in | 0.85940.859375 | 21.828 | |
| 7/8 in | 0.8750 | 22.225 | |
| 57/64 in | 0.89060.890625 | 22.622 | |
| 29/32 in | 0.90630.90625 | 23.019 | |
| 59/64 in | 0.92190.921875 | 23.416 | |
| 15/16 in | 0.9375 | 23.813 | |
| 61/64 in | 0.95310.953125 | 24.209 | |
| 31/32 in | 0.96880.96875 | 24.606 | |
| 63/64 in | 0.98440.984375 | 25.003 | |
| 1 in | 1.0000 | 25.400 | |
| 1-1/16 in | 1.0625 | 26.988 | |
| 1-1/8 in | 1.1250 | 28.575 | |
| 1-3/16 in | 1.1875 | 30.163 | |
| 1-1/4 in | 1.2500 | 31.750 | |
| 1-5/16 in | 1.3125 | 33.338 | |
| 1-3/8 in | 1.3750 | 34.925 | |
| 1-7/16 in | 1.4375 | 36.513 | |
| 1-1/2 in | 1.5000 | 38.100 | |
| 1-9/16 in | 1.5625 | 39.688 | |
| 1-5/8 in | 1.6250 | 41.275 | |
| 1-11/16 in | 1.6875 | 42.863 | |
| 1-3/4 in | 1.7500 | 44.450 | |
| 1-13/16 in | 1.8125 | 46.038 | |
| 1-7/8 in | 1.8750 | 47.625 | |
| 1-15/16 in | 1.9375 | 49.213 | |
| 2 in | 2.0000 | 50.800 | |
| 2-1/4 in | 2.2500 | 57.150 | |
| 2-1/2 in | 2.5000 | 63.500 | |
| 2-3/4 in | 2.7500 | 69.850 | |
| 3 in | 3.0000 | 76.200 | |
| 3-1/4 in | 3.2500 | 82.550 | |
| 3-1/2 in | 3.5000 | 88.900 | |
| 3-3/4 in | 3.7500 | 95.250 | |
| 4 in | 4.0000 | 101.600 |
From the standard, the international inch, 25.4 mm exactly
How to convert a fraction
Divide the top number by the bottom one: 3/16 is 3 ÷ 16 = 0.1875 inch. For millimeters, multiply the decimal by 25.4, which is exact by definition: 0.1875 × 25.4 = 4.7625 mm. To go the other way, from a decimal to the nearest 64th, multiply by 64 and round: 0.300 × 64 = 19.2, so 19/64 inch, which is 0.2969, about 0.003 inch small.
A tape measure is marked in 16ths, a good steel rule in 32nds or 64ths. The "Show every" choice hides the finer rows when you only want the marks on your tape. Eighths and coarser are bold on a shaded band and 64ths are lighter, so the steps read without color.
The sizes in the last column come from the site's own charts. 3/4 inch is a 3/4 drill, plywood stamped 3/4, Baltic birch sold as 3/4 (18 mm, a little thinner), 3/4 rough hardwood and a dressed 1x board. 13/16 is 4/4 hardwood surfaced on two sides, and 1-1/2 is a dressed 2x. See the plywood thickness chart, the hardwood thickness chart and the drill bit size chart for the rest of each standard.