Hole Size
Tap Drills and Clearance Drills for Machine Screws with American National Thread Form
| Size of Screw | No. of Threads per Inch | Tap Drills | Clearance Hole Drills | |||||
|---|---|---|---|---|---|---|---|---|
| No. or Diam. | Decimal Equiv. | Drill Size | Decimal Equiv. | Close Fit | Free Fit | |||
| Drill Size | Decimal Equiv. | Drill Size | Decimal Equiv. | |||||
| 0 | 0.060 | 80 | 3/64 | 0.0469 | 52 | 0.0635 | 50 | 0.0700 |
| 1 | 0.073 | 64 72 | 53 53 | 0.0595 0.0595 | 48 | 0.0760 | 46 | 0.0810 |
| 2 | 0.086 | 56 64 | 50 50 | 0.0700 0.0700 | 43 | 0.0890 | 41 | 0.0960 |
| 3 | 0.099 | 48 56 | 47 45 | 0.0785 0.0820 | 37 | 0.1040 | 35 | 0.1100 |
| 4 | 0.112 | 36a 40 48 | 44 43 42 | 0.0860 0.0890 0.0935 | 32 | 0.1160 | 30 | 0.1285 |
| 5 | 0.125 | 40 44 | 38 37 | 0.1015 0.1040 | 30 | 0.1285 | 29 | 0.1360 |
| 6 | 0.138 | 32 40 | 36 33 | 0.1065 0.1130 | 27 | 0.1440 | 25 | 0.1495 |
| 8 | 0.164 | 32 36 | 29 29 | 0.1360 0.1360 | 18 | 0.1695 | 16 | 0.1770 |
| 10 | 0.190 | 24 32 | 25 21 | 0.1495 0.1590 | 9 | 0.1960 | 7 | 0.2010 |
| 12 | 0.216 | 24 28 | 16 14 | 0.1770 0.1820 | 2 | 0.2210 | 1 | 0.2280 |
| 14 | 0.242 | 20a 24a | 10 7 | 0.1935 0.2010 | D | 0.2460 | F | 0.2570 |
| 1/4 | 0.250 | 20 28 | 7 3 | 0.2010 0.2130 | F | 0.2570 | H | 0.2660 |
| 5/16 | 0.3125 | 18 24 | F I | 0.2570 0.2720 | P | 0.3230 | Q | 0.3320 |
| 3/8 | 0.375 | 16 24 | 5/16 Q | 0.3125 0.3320 | W | 0.3860 | X | 0.3970 |
| 7/16 | 0.4375 | 14 20 | U 25/64 | 0.3680 0.3906 | 29/64 | 0.4531 | 15/32 | 0.4687 |
| 1/2 | 0.500 | 13 20 | 27/64 29/64 | 0.4219 0.4531 | 33/64 | .5156 | 17/32 | .5312 |
British Standard Metric Bolt and Screw Clearance Holes BS 4186: 1967
| Nominal Thread Diameter | Close Fit Series | Medium Fit Series | Free Fit Series |
|---|---|---|---|
| 1.6 | 1.7 | 1.8 | 2.0 |
| 2.0 | 2.2 | 2.4 | 2.6 |
| 2.5 | 2.7 | 2.9 | 3.1 |
| 3.0 | 3.2 | 3.4 | 3.6 |
| 4.0 | 4.3 | 4.5 | 4.8 |
| 5.0 | 5.3 | 5.5 | 5.8 |
| 6.0 | 6.4 | 6.6 | 7.0 |
| 7.0 | 7.4 | 7.6 | 8.0 |
| 8.0 | 8.4 | 9.0 | 10.0 |
| 10.0 | 10.5 | 11.0 | 12.0 |
| 12.0 | 13.0 | 14.0 | 15.0 |
| 14.0 | 15.0 | 16.0 | 17.0 |
| 16.0 | 17.0 | 18.0 | 19.0 |
| 18.0 | 19.0 | 20.0 | 21.0 |
| 20.0 | 21.0 | 22.0 | 24.0 |
| 22.0 | 23.0 | 24.0 | 26.0 |
| 24.0 | 25.0 | 26.0 | 28.0 |
| 27.0 | 28.0 | 30.0 | 32.0 |
| 30.0 | 31.0 | 33.0 | 35.0 |
| 33.0 | 34.0 | 36.0 | 38.0 |
| 36.0 | 37.0 | 39.0 | 42.0 |
| 39.0 | 40.0 | 42.0 | 45.0 |
| 42.0 | 43.0 | 45.0 | 48.0 |
| 45.0 | 46.0 | 48.0 | 52.0 |
| 48.0 | 50.0 | 52.0 | 56.0 |
| 52.0 | 54.0 | 56.0 | 62.0 |
| 56.0 | 58.0 | 62.0 | 66.0 |
| 60.0 | 62.0 | 66.0 | 70.0 |
| 64.0 | 66.0 | 70.0 | 74.0 |
| 68.0 | 70.0 | 74.0 | 78.0 |
| 72.0 | 74.0 | 78.0 | 82.0 |
| 76.0 | 78.0 | 82.0 | 86.0 |
| 80.0 | 82.0 | 86.0 | 91.0 |
| 85.0 | 87.0 | 91.0 | 96.0 |
| 90.0 | 93.0 | 96.0 | 101.0 |
| 95.0 | 98.0 | 101.0 | 107.0 |
| 100.0 | 104.0 | 107.0 | 112.0 |
| 105.0 | 109.0 | 112.0 | 117.0 |
| 110.0 | 114.0 | 117.0 | 122.0 |
| 115.0 | 119.0 | 122.0 | 127.0 |
| 120.0 | 124.0 | 127.0 | 132.0 |
| 125.0 | 129.0 | 132.0 | 137.0 |
| 130.0 | 134.0 | 137.0 | 144.0 |
| 140.0 | 144.0 | 147.0 | 155.0 |
| 150.0 | 155.0 | 158.0 | 165.0 |
All dimensions are given in millimeters.