This chart gives the decimal equivalent of fractional, number, letter, and metric sizes in order of increasing size.
Reference Only. See Terms of Use.
| FRACTION | # SIZE | LETTER | METRIC | DECIMAL INCHES |
| #80 | 0.0135 | |||
| #79 | 0.0145 | |||
| 1/64 | 0.0156 | |||
| #78 | 0.0160 | |||
| #77 | 0.0180 | |||
| 0.5mm | 0.0197 | |||
| #76 | 0.0200 | |||
| #75 | 0.0210 | |||
| #74 | 0.0225 | |||
| #73 | 0.0240 | |||
| #72 | 0.0250 | |||
| #71 | 0.0260 | |||
| #70 | 0.0280 | |||
| #69 | 0.0292 | |||
| 0.75mm | 0.0295 | |||
| #68 | 0.0310 | |||
| 1/32 | 0.0312 | |||
| #67 | 0.0320 | |||
| #66 | 0.0330 | |||
| #65 | 0.0350 | |||
| #64 | 0.0360 | |||
| #63 | 0.0370 | |||
| #62 | 0.0380 | |||
| #61 | 0.0390 | |||
| 1mm | 0.0394 | |||
| #60 | 0.0400 | |||
| #59 | 0.0410 | |||
| #58 | 0.0420 | |||
| #57 | 0.0430 | |||
| #56 | 0.0465 | |||
| 3/64 | 0.0469 | |||
| 1.25mm | 0.0492 | |||
| #55 | 0.0520 | |||
| #54 | 0.0550 | |||
| 1.5mm | 0.0591 | |||
| #53 | 0.0595 | |||
| 1/16 | 0.0625 | |||
| #52 | 0.0635 | |||
| #51 | 0.0670 | |||
| 1.75mm | 0.0689 | |||
| #50 | 0.0700 | |||
| #49 | 0.0730 | |||
| #48 | 0.0760 | |||
| 5/64 | 0.0781 | |||
| #47 | 0.0785 | |||
| 2mm | 0.0787 | |||
| #46 | 0.0810 | |||
| #45 | 0.0820 | |||
| #44 | 0.0860 | |||
| 2.25mm | 0.0886 | |||
| #43 | 0.0890 | |||
| #42 | 0.0935 | |||
| 3/32 | 0.0938 | |||
| #41 | 0.0960 | |||
| #40 | 0.0980 | |||
| 2.5mm | 0.0984 | |||
| #39 | 0.0995 | |||
| #38 | 0.1015 | |||
| #37 | 0.1040 | |||
| #36 | 0.1065 | |||
| 2.75mm | 0.1083 | |||
| 7/64 | 0.1094 | |||
| #35 | 0.1100 | |||
| #34 | 0.1110 | |||
| #33 | 0.1130 | |||
| #32 | 0.1160 | |||
| 3mm | 0.1181 | |||
| #31 | 0.1200 | |||
| 1/8 | 0.1250 | |||
| 3.25mm | 0.1280 | |||
| #30 | 0.1285 | |||
| #29 | 0.1360 | |||
| 3.5mm | 0.1378 | |||
| #28 | 0.1405 | |||
| 9/64 | 0.1406 | |||
| #27 | 0.1440 | |||
| #26 | 0.1470 | |||
| 3.75mm | 0.1476 | |||
| #25 | 0.1495 | |||
| #24 | 0.1520 | |||
| #23 | 0.1540 | |||
| 5/32 | 0.1562 | |||
| #22 | 0.1570 | |||
| 4mm | 0.1575 | |||
| #21 | 0.1590 | |||
| #20 | 0.1610 | |||
| #19 | 0.1660 | |||
| 4.25mm | 0.1673 | |||
| #18 | 0.1695 | |||
| 11/64 | 0.1719 | |||
| #17 | 0.1730 | |||
| #16 | 0.1770 | |||
| 4.5mm | 0.1772 | |||
| #15 | 0.1800 | |||
| #14 | 0.1820 | |||
| #13 | 0.1850 | |||
| 4.75mm | 0.1870 | |||
| 3/16 | 0.1875 | |||
| #12 | 0.1890 | |||
| #11 | 0.1910 | |||
| #10 | 0.1935 | |||
| #9 | 0.1960 | |||
| 5mm | 0.1969 | |||
| #8 | 0.1990 | |||
| #7 | 0.2010 | |||
| 13/64 | 0.2031 | |||
| #6 | 0.2040 | |||
| #5 | 0.2055 | |||
| 5.25mm | 0.2067 | |||
| #4 | 0.2090 | |||
| #3 | 0.2130 | |||
| 5.5mm | 0.2165 | |||
| 7/32 | 0.2188 | |||
| #2 | 0.2210 | |||
| 5.75mm | 0.2264 | |||
| #1 | 0.2280 | |||
| A | 0.2340 | |||
| 15/64 | 0.2344 | |||
| 6mm | 0.2362 | |||
| B | 0.2380 | |||
| C | 0.2420 | |||
| D | 0.2460 | |||
| 6.25mm | 0.2461 | |||
| 1/4 | E | 0.2500 | ||
| 6.5mm | 0.2559 | |||
| F | 0.2570 | |||
| G | 0.2610 | |||
| 17/64 | 0.2656 | |||
| 6.75mm | 0.2657 | |||
| H | 0.2660 | |||
| I | 0.2720 | |||
| 7mm | 0.2756 | |||
| J | 0.2770 | |||
| K | 0.2810 | |||
| 9/32 | 0.2812 | |||
| 7.25mm | 0.2854 | |||
| L | 0.2900 | |||
| M | 0.2950 | |||
| 7.5mm | 0.2953 | |||
| 19/64 | 0.2969 | |||
| N | 0.3020 | |||
| 7.75mm | 0.3051 | |||
| 5/16 | 0.3125 | |||
| 8mm | 0.3150 | |||
| O | 0.3160 | |||
| P | 0.3230 | |||
| 8.25mm | 0.3248 | |||
| 21/64 | 0.3281 | |||
| Q | 0.3320 | |||
| 8.5mm | 0.3346 | |||
| R | 0.3390 | |||
| 11/32 | 0.3438 | |||
| 8.75mm | 0.3445 | |||
| S | 0.3480 | |||
| 9mm | 0.3543 | |||
| T | 0.3580 | |||
| 23/64 | 0.3594 | |||
| 9.25mm | 0.3642 | |||
| U | 0.3680 | |||
| 9.5mm | 0.3740 | |||
| 3/8 | 0.3750 | |||
| V | 0.3770 | |||
| 9.75mm | 0.3839 | |||
| W | 0.3860 | |||
| 25/64 | 0.3906 | |||
| 10mm | 0.3937 | |||
| X | 0.3970 | |||
| Y | 0.4040 | |||
| 13/32 | 0.4063 | |||
| Z | 0.4130 | |||
| 10.5mm | 0.4134 | |||
| 27/64 | 0.4219 | |||
| 11mm | 0.4331 | |||
| 7/16 | 0.4375 | |||
| 11.5mm | 0.4528 | |||
| 29/64 | 0.4531 | |||
| 15/32 | 0.4688 | |||
| 12mm | 0.4724 | |||
| 31/64 | 0.4844 | |||
| 12.5mm | 0.4921 | |||
| 1/2 | 0.5000 | |||
| 13mm | 0.5118 | |||
| 33/64 | 0.5156 | |||
| 17/32 | 0.5312 | |||
| 13.5mm | 0.5315 | |||
| 35/64 | 0.5469 | |||
| 14mm | 0.5512 | |||
| 9/16 | 0.5625 | |||
| 14.5mm | 0.5709 | |||
| 37/64 | 0.5781 | |||
| 15mm | 0.5906 | |||
| 19/32 | 0.5938 | |||
| 39/64 | 0.6094 | |||
| 15.5mm | 0.6102 | |||
| 5/8 | 0.6250 | |||
| 16mm | 0.6299 | |||
| 41/64 | 0.6406 | |||
| 16.5mm | 0.6496 | |||
| 21/32 | 0.6562 | |||
| 17mm | 0.6693 | |||
| 43/64 | 0.6719 | |||
| 11/16 | 0.6875 | |||
| 17.5mm | 0.6890 | |||
| 45/64 | 0.7031 | |||
| 18mm | 0.7087 | |||
| 23/32 | 0.7188 | |||
| 18.5mm | 0.7283 | |||
| 47/64 | 0.7344 | |||
| 19mm | 0.7480 | |||
| 3/4 | 0.7500 | |||
| 49/64 | 0.7656 | |||
| 19.5mm | 0.7677 | |||
| 25/32 | 0.7813 | |||
| 20mm | 0.7874 | |||
| 51/64 | 0.7969 | |||
| 20.5mm | 0.8071 | |||
| 13/16 | 0.8125 | |||
| 21mm | 0.8268 | |||
| 53/64 | 0.8281 | |||
| 27/32 | 0.8438 | |||
| 21.5mm | 0.8465 | |||
| 55/64 | 0.8594 | |||
| 22mm | 0.8661 | |||
| 7/8 | 0.8750 | |||
| 22.5mm | 0.8858 | |||
| 57/64 | 0.8906 | |||
| 23mm | 0.9055 | |||
| 29/32 | 0.9062 | |||
| 59/64 | 0.9219 | |||
| 23.5mm | 0.9252 | |||
| 15/16 | 0.9375 | |||
| 24mm | 0.9449 | |||
| 61/64 | 0.9531 | |||
| 24.5mm | 0.9646 | |||
| 31/32 | 0.9688 | |||
| 25mm | 0.9843 | |||
| 63/64 | 0.9844 | |||
| 1 inch | 1.0000 |
For design, see:
- ASME B94.11 – Twist Drills
- This Standard covers nomenclature, definitions, sizes and tolerances of High Speed Steel, Straight and Taper Shank Drills, and Combined Drills and Countersinks, Plain and Bell Type. It covers both inch and metric size drills.
- ASME B18.2.8 – Clearance holes for bolts, screws and studs
- This Standard covers the recommended clearance hole sizes for #0 through 1.5 in. and M1.6 through M100 metric fasteners in three classes of clearance using a close-, normal-, and loose-fit category.