Enjoy our reference chart with the standard and not so standard metric and imperial fastener sizes. With over 250 metric sizes, the chart displays the equivalent fraction and decimal number for easy cross referencing. Useful when you are trying to narrow the size down to the absolute closest mm or fraction of an inch.
| METRIC | IMPERIAL | |
|---|---|---|
| Millimetres (mm) | Fractional (in”) | Decimal |
| 0.10 | – | 0.0039 |
| 0.20 | – | 0.0079 |
| 0.30 | – | 0.0118 |
| 0.39 | 1/64 | 0.0156 |
| 0.40 | – | 0.0157 |
| 0.50 | – | 0.0197 |
| 0.60 | – | 0.0236 |
| 0.70 | – | 0.0276 |
| 0.79 | 1/32 | 0.0313 |
| 0.80 | – | 0.0315 |
| 0.90 | – | 0.0354 |
| 1.00 | – | 0.0394 |
| 1.10 | – | 0.0433 |
| 1.90 | 3/64 | 0.0469 |
| 1.20 | – | 0.0472 |
| 1.30 | – | 0.0512 |
| 1.40 | – | 0.0551 |
| 1.50 | – | 0.0591 |
| 1.59 | 1/16 | 0.0625 |
| 1.60 | – | 0.063 |
| 1.70 | – | 0.0669 |
| 1.80 | – | 0.0709 |
| 1.90 | – | 0.0748 |
| 1.98 | 5/64 | 0.0781 |
| 2.00 | – | 0.0787 |
| 2.10 | – | 0.0827 |
| 2.20 | – | 0.0866 |
| 2.30 | – | 0.0906 |
| 2.38 | 3/32 | 0.0938 |
| 2.40 | – | 0.0945 |
| 2.50 | – | 0.0984 |
| 2.78 | 7/64 | 0.1094 |
| 3.00 | – | 0.1181 |
| 3.18 | 1/8 | 0.125 |
| 3.50 | – | 0.1378 |
| 3.57 | 9/64 | 0.1406 |
| 3.97 | 5/32 | 0.1563 |
| 4.00 | – | 0.1575 |
| 4.37 | 11/64 | 0.1719 |
| 4.50 | – | 0.1772 |
| 4.76 | 3/16 | 0.1875 |
| 5.00 | – | 0.1969 |
| 5.16 | 13/64 | 0.2031 |
| 5.5 | – | 0.2165 |
| 5.56 | 7/32 | 0.2188 |
| 5.95 | 15/64 | 0.2344 |
| 6.00 | – | 0.2362 |
| 6.35 | 1/4 | 0.25 |
| 6.50 | – | 0.2559 |
| 6.75 | 17/64 | 0.2656 |
| 7.00 | – | 0.2756 |
| 7.14 | 9/32 | 0.2813 |
| 7.50 | – | 0.2953 |
| 7.54 | 19/64 | 0.2969 |
| 7.94 | 5/16 | 0.3125 |
| 8.00 | – | 0.315 |
| 8.33 | 21/64 | 0.3281 |
| 8.50 | – | 0.3346 |
| 8.73 | 11/32 | 0.3438 |
| 9.00 | – | 0.3543 |
| 9.13 | 23/64 | 0.3594 |
| 9.50 | – | 0.374 |
| 9.53 | 3/8 | 0.375 |
| 9.92 | 25/64 | 0.3906 |
| 10.00 | – | 0.3937 |
| 10.32 | 13/32 | 0.4063 |
| 10.50 | – | 0.4134 |
| 10.72 | 27/64 | 0.4219 |
| 11.00 | – | 0.4331 |
| 11.11 | 7/16 | 0.4375 |
| 11.50 | – | 0.4528 |
| 11.51 | 29/64 | 0.4531 |
| 11.91 | 15/32 | 0.4688 |
| 12.00 | – | 0.4724 |
| 12.30 | 31/64 | 0.4844 |
| 12.50 | – | 0.4921 |
| 12.70 | 1/2 | 0.5 |
| 13.00 | – | 0.5118 |
| 13.10 | 33/64 | 0.5156 |
| 13.49 | 17/32 | 0.5313 |
| 13.50 | – | 0.5315 |
| 13.89 | 35/64 | 0.5469 |
| 14.00 | – | 0.551 |
| 14.29 | 9/16 | 0.563 |
| 14.50 | – | 0.571 |
| 14.68 | 37/64 | 0.578 |
| 15.00 | – | 0.591 |
| 15.08 | 19/32 | 0.594 |
| 15.48 | 39/64 | 0.609 |
| 15.50 | – | 0.610 |
| 15.88 | 5/8 | 0.625 |
| 16.00 | – | 0.630 |
| 16.27 | 41/64 | 0.641 |
| 16.50 | – | 0.650 |
| 16.67 | 21/32 | 0.656 |
| 17.00 | – | 0.669 |
| 17.07 | 43/64 | 0.672 |
| 17.46 | 11/16 | 0.688 |
| 17.50 | – | 0.689 |
| 17.86 | 45/64 | 0.703 |
| 18.00 | – | 0.709 |
| 18.26 | 23/32 | 0.719 |
| 18.50 | – | 0.728 |
| 18.65 | 47/64 | 0.734 |
| 19.00 | – | 0.748 |
| 19.05 | 3/4 | 0.75 |
| 19.45 | 49/64 | 0.766 |
| 19.50 | – | 0.768 |
| 19.84 | 25/32 | 0.781 |
| 20.00 | – | 0.787 |
| 20.24 | 51/64 | 0.797 |
| 20.50 | – | 0.807 |
| 20.64 | 13/16 | 0.813 |
| 21.00 | – | 0.827 |
| 21.03 | 53/64 | 0.828 |
| 21.43 | 27/32 | 0.844 |
| 21.50 | – | 0.847 |
| 21.83 | 55/64 | 0.859 |
| 22.00 | – | 0.866 |
| 22.23 | 7/8 | 0.875 |
| 22.50 | – | 0.886 |
| 22.62 | 57/64 | 0.891 |
| 23.00 | – | 0.906 |
| 23.02 | 29/32 | 0.906 |
| 23.42 | 59/64 | 0.922 |
| 23.50 | – | 0.925 |
| 23.81 | 15/16 | 0.938 |
| 24.00 | – | 0.945 |
| 24.21 | 61/64 | 0.953 |
| 24.50 | – | 0.965 |
| 24.61 | 31/32 | 0.969 |
| 25.00 | 63/64 | 0.984 |
| 25.40 | 1 | 1 |
| 25.50 | – | 1.004 |
| 26.00 | – | 1.024 |
| 26.50 | – | 1.043 |
| 27.00 | – | 1.063 |
| 27.50 | – | 1.083 |
| 28.00 | – | 1.102 |
| 28.50 | – | 1.122 |
| 29.00 | – | 1.142 |
| 29.50 | – | 1.161 |
| 30.00 | – | 1.181 |
| 31.00 | – | 1.221 |
| 31,75 | 1-1/4 | 1.25 |
| 32.00 | – | 1.260 |
| 33.00 | – | 1.299 |
| 34.00 | – | 1.339 |
| 34.90 | 1-3/8 | 1.375 |
| 36.00 | – | 1.417 |
| 37.00 | – | 1.457 |
| 38.00 | – | 1.496 |
| 38.10 | 1-1/2 | 1.5 |
| 39.00 | – | 1.535 |
| 40.00 | – | 1.575 |
| 41.00 | – | 1.614 |
| 42.00 | – | 1.654 |
| 43.00 | – | 1.693 |
| 44.00 | – | 1.732 |
| 44.45 | 1-3/4 | 1.75 |
| 45.00 | – | 1.772 |
| 46.00 | – | 1.811 |
| 47.00 | – | 1.850 |
| 48.00 | – | 1.8898 |
| 49.00 | – | 1.9291 |
| 50.00 | – | 1.9685 |
| 50.80 | 2 | 2 |
| 51.00 | – | 2.0079 |
| 52.00 | – | 2.0472 |
| 53.00 | – | 2.0866 |
| 54.00 | 2-1/8 | 2.125 |
| 55.00 | – | 2.1654 |
| 56.00 | – | 2.2047 |
| 57.00 | – | 2.2441 |
| 57.15 | 2-1/4 | 2.25 |
| 58.00 | – | 2.2835 |
| 59.00 | – | 2.3228 |
| 60.30 | 2-3/8 | 2.3675 |
| 61.00 | – | 2.4016 |
| 62.00 | – | 2.4409 |
| 63.00 | – | 2.4803 |
| 63.50 | 2-1/2 | 2.5 |
| 64.00 | – | 2.5197 |
| 65.00 | – | 2.5591 |
| 66.00 | – | 2.5984 |
| 66.70 | 2-5/8 | 2.625 |
| 68.00 | – | 2.6772 |
| 69.00 | – | 2.7165 |
| 69.85 | 2-3/4 | 2.75 |
| 70.00 | – | 2.7559 |
| 71.00 | – | 2.7953 |
| 72.00 | – | 2.8346 |
| 73.00 | – | 2.874 |
| 74.00 | – | 2.9134 |
| 75.00 | – | 2.9528 |
| 76.00 | – | 2.9921 |
| 76.20 | 3 | 3 |
| 77.00 | – | 3.0315 |
| 78.00 | – | 3.0709 |
| 79.00 | – | 3.1102 |
| 80.00 | – | 3.1496 |
| 81.00 | – | 3.189 |
| 82.00 | – | 3.2283 |
| 83.00 | – | 3.2677 |
| 84.00 | – | 3.3071 |
| 85.00 | – | 3.3465 |
| 86.00 | – | 3.3858 |
| 87.00 | – | 3.4252 |
| 88.00 | – | 3.4646 |
| 88.90 | 3-1/2 | 3.5 |
| 89.00 | – | 3.5039 |
| 90.00 | – | 3.5433 |
| 91.00 | – | 3.5827 |
| 92.00 | – | 3.622 |
| 93.00 | – | 3.6614 |
| 94.00 | – | 3.7008 |
| 95.00 | – | 3.7402 |
| 96.00 | – | 3.7795 |
| 97.00 | – | 3.8189 |
| 98.00 | – | 3.8583 |
| 99.00 | – | 3.8976 |
| 100.00 | – | 3.937 |
| 101.60 | 4 | 4 |
| 110.00 | – | 4.3307 |
| 114.30 | 4-1/2 | 4.5 |
| 120.00 | – | 4.7244 |
| 127.00 | 5 | 5 |
| 130.00 | – | 5.1181 |
| 140.00 | – | 5.5118 |
| 150.00 | – | 5.9055 |
| 152.40 | 6 | 6 |
| 160.00 | – | 6.2992 |
| 170.00 | – | 6.6929 |
| 177.80 | 7 | 7 |
| 190.00 | – | 7.4803 |
| 200.00 | – | 7.87 |
| 203.20 | 8 | 8 |
| 250.00 | – | 9.84 |
| 254.00 | 10 | 10 |
| 279.40 | 11 | 11 |
| 304.80 | 12 | 12 |
| 330.02 | 13 | 13 |
| 355.60 | 14 | 14 |
| 381.00 | 15 | 15 |
| 508.00 | 20 | 20 |
| 635.00 | 25 | 25 |