Our screw tap drill size chart provides you with a comprehensive guide to selecting the perfect drill size for your screw taps. Whether you’re working with american, metric or inch threads, coarse or fine, this table has you covered.
Our screw tap drill size chart can be provided in the form of a PDF file. You can print this file to use it in your shop. To download the file directly, simply click the “Download” button. Alternatively, click the link below to access the PDF page and then click the “Download icon” to choose where you want to save the document.
Metric Coarse Thread
| Metric Tap Size | Standard Diameter | Class 2 Tap Drill Size | |
| Maximum | Minimum | ||
| M1.0x0.25 | 0.75 | 0.785 | 0.729 |
| M1.1×0.25 | 0.85 | 0.885 | 0.829 |
| M1.2×0.25 | 0.95 | 0.985 | 0.929 |
| M1.4×0.3 | 1.10 | 1.142 | 1.075 |
| M1.6×0.35 | 1.45 | 1.521 | 1.421 |
| M2.0x0.4 | 1.60 | 1.679 | 1.567 |
| M2.2×0.45 | 1.75 | 1.838 | 1.713 |
| M2.3×0.4 | 1.90 | 1.979 | 1.867 |
| M2.5×0.45 | 2.10 | 2.138 | 2.013 |
| M2.6×0.45 | 2.20 | 2.238 | 2.113 |
| M3.0x0.5 | 2.50 | 2.599 | 2.459 |
| M3.5×0.6 | 2.90 | 3.010 | 2.850 |
| M4.0x0.7 | 3.30 | 3.422 | 3.242 |
| M4.5×0.75 | 3.80 | 3.878 | 3.688 |
| M5.0x0.8 | 4.20 | 4.334 | 4.134 |
| M6.0x1.0 | 5.00 | 5.153 | 4.917 |
| M7.0x1.0 | 6.00 | 6.153 | 5.917 |
| M8.0x1.25 | 6.80 | 6.912 | 6.647 |
| M9.0x1.25 | 7.80 | 7.912 | 7.647 |
| M10x1.5 | 8.50 | 8.676 | 8.376 |
| M11x1.5 | 9.50 | 9.676 | 9.376 |
| M12x1.75 | 10.30 | 10.441 | 10.106 |
| M14x2.0 | 12.00 | 12.210 | 11.835 |
| M16×2.0 | 14.00 | 14.210 | 13.835 |
| M18x2.5 | 15.50 | 15.744 | 15.294 |
| M20x2.5 | 17.50 | 17.744 | 17.294 |
| M22×2.5 | 19.50 | 19.744 | 19.294 |
| M24x3.0 | 21.00 | 21.252 | 20.752 |
| M27x3.0 | 24.00 | 24.252 | 23.752 |
| M30x3.5 | 26.50 | 26.771 | 26.211 |
| M33x3.5 | 29.50 | 29.771 | 29.221 |
| M36x4.0 | 32.00 | 32.270 | 31.670 |
| M39x4.0 | 35.00 | 35.270 | 34.670 |
Metric Fine Thread
| Metric Tap Size | Standard Diameter | Class 2 Tap Drill Size | |
| Maximum | Minimum | ||
| M1.0x0.2 | 0.80 | 0.821 | 0.783 |
| M1.1×0.2 | 0.90 | 0.921 | 0.883 |
| M1.2×0.2 | 1.00 | 1.021 | 0.983 |
| M1.4×0.2 | 1.20 | 1.221 | 1.183 |
| M1.6×0.2 | 1.40 | 1.421 | 1.383 |
| M1.7×0.2 | 1.50 | 1.521 | 1.483 |
| M1.8×0.2 | 1.60 | 1.621 | 1.583 |
| M2.0x0.25 | 1.75 | 1.785 | 1.729 |
| M2.2×0.25 | 1.95 | 1.985 | 1.929 |
| M2.3×0.25 | 2.05 | 2.061 | 2.001 |
| M2.5×0.35 | 2.20 | 2.221 | 2.121 |
| M2.6×0.35 | 2.20 | 2.246 | 2.186 |
| M3.0x0.35 | 2.70 | 2.721 | 2.621 |
| M3.5×0.35 | 3.20 | 3.221 | 3.121 |
| M4.0x0.5 | 3.50 | 3.599 | 3.459 |
| M4.5×0.5 | 4.00 | 4.099 | 3.959 |
| M5.0x0.5 | 4.50 | 4.599 | 4.459 |
| M5.5×0.5 | 5.00 | 5.099 | 4.959 |
| M6.0x0.75 | 5.30 | 5.378 | 5.188 |
| M6.0x0.5 | 5.50 | 5.550 | 5.400 |
| M7.0x0.75 | 6.30 | 6.378 | 6.188 |
| M7.0x0.5 | 6.50 | 6.550 | 6.400 |
| M8.0x1.0 | 7.00 | 7.153 | 6.917 |
| M8.0x0.75 | 7.30 | 7.378 | 7.188 |
| M8.0x0.5 | 7.50 | 7.520 | 7.400 |
| M9.0x1.0 | 8.00 | 8.153 | 7.917 |
| M9.0x0.75 | 8.30 | 8.378 | 8.188 |
| M10x1.25 | 8.80 | 8.912 | 8.647 |
| M10x1.0 | 9.00 | 9.153 | 8.917 |
| M10x0.75 | 9.30 | 9.378 | 9.188 |
| M10x0.5 | 9.50 | 9.520 | 9.400 |
| M11x1.0 | 10.00 | 10.153 | 9.917 |
| M11x0.75 | 10.30 | 10.378 | 10.188 |
| M12x1.5 | 10.50 | 10.676 | 10.376 |
| M12x1.25 | 10.80 | 10.912 | 10.647 |
| M12x1.0 | 11.00 | 11.153 | 10.917 |
| M12x0.5 | 11.50 | 11.520 | 11.400 |
| M14x1.5 | 12.50 | 12.676 | 12.376 |
| M14x1.0 | 13.00 | 13.153 | 12.917 |
| M15x1.5 | 13.50 | 13.676 | 13.376 |
| M15x1.0 | 14.00 | 14.153 | 13.917 |
| M16x1.5 | 14.50 | 14.676 | 14.376 |
| M16x1.0 | 15.00 | 15.153 | 14.917 |
| M17x1.5 | 15.50 | 15.676 | 15.376 |
| M17x1.0 | 16.00 | 16.153 | 15.917 |
| M18x2.0 | 16.00 | 16.210 | 15.835 |
| M18x1.5 | 16.50 | 16.676 | 16.376 |
| M18x1.0 | 17.00 | 17.153 | 16.917 |
| M20x2.0 | 18.00 | 18.210 | 17.835 |
| M20x1.5 | 18.50 | 18.676 | 18.376 |
| M20x1.0 | 19.00 | 19.153 | 18.917 |
| M22x2.0 | 20.00 | 20.210 | 19.835 |
| M22x1.5 | 20.50 | 20.676 | 20.376 |
| M22x1.0 | 21.00 | 21.153 | 20.917 |
| M24x2.0 | 22.00 | 22.210 | 21.835 |
| M24x1.5 | 22.50 | 22.676 | 22.376 |
| M24x1.0 | 23.00 | 23.153 | 22.917 |
| M25×2.0 | 23.00 | 23.210 | 22.835 |
| M25x1.5 | 23.50 | 23.670 | 23.370 |
| M25x1.0 | 24.00 | 24.153 | 23.917 |
| M26x1.5 | 24.50 | 24.676 | 24.376 |
| M27x2.0 | 25.00 | 25.210 | 24.835 |
| M27x1.5 | 25.50 | 25.676 | 25.376 |
| M27x1.0 | 26.00 | 26.153 | 25.917 |
| M28x2.0 | 26.00 | 26.210 | 25.835 |
| M28x1.5 | 26.50 | 26.676 | 26.376 |
| M28x1.0 | 27.00 | 27.153 | 26.917 |
| M30x3.0 | 27.00 | 27.252 | 26.752 |
| M30x2.0 | 28.00 | 28.210 | 27.835 |
| M30x1.5 | 28.50 | 28.676 | 28.376 |
| M30x1.0 | 29.00 | 29.153 | 28.917 |
| M32x2.0 | 30.00 | 30.210 | 29.835 |
| M32x1.5 | 30.50 | 30.676 | 30.376 |
| M33x3.0 | 30.00 | 30.252 | 29.752 |
| M33x2.0 | 31.00 | 31.210 | 30.835 |
| M33x1.5 | 31.50 | 31.676 | 31.376 |
| M35x1.5 | 33.50 | 33.676 | 33.376 |
| M36x3.0 | 33.00 | 33.252 | 32.752 |
| M36x2.0 | 34.00 | 34.210 | 33.835 |
| M36x1.5 | 34.50 | 34.676 | 34.376 |
American Fine Thread
| Screw Tap Size(UNF) | Standard Diameter | Class 2 Tap Drill Size | |
| Maximum | Minimum | ||
| NO.O -80(1524) | 1.25 | 1.305 | 1.182 |
| NO.1 -72(1.854) | 1.55 | 1.612 | 1.474 |
| NO.2 -64(2184) | 1.85 | 1.912 | 1.756 |
| NO.3 -56(2515) | 2.10 | 2.197 | 2.025 |
| NO.4 -48(2845) | 2.40 | 2.458 | 2.271 |
| NO.5 -44(3715) | 2.70 | 2.740 | 2.551 |
| NO.6 -40(3.505) | 2.90 | 3.022 | 2.820 |
| NO.8 -36(4.166) | 3.50 | 3.606 | 3.404 |
| NO.10 -32(4.826) | 4.10 | 4.165 | 3.963 |
| NO.12 -28(5.486) | 4.60 | 4.724 | 4.496 |
| 1/4 -28 | 5.50 | 5.588 | 5.360 |
| 5/16 -24 | 6.90 | 7.035 | 6.782 |
| 3/8 -24 | 8.50 | 8.636 | 8.382 |
| 7/16 -20 | 9.90 | 10.033 | 9.729 |
| 1/2 -20 | 11.50 | 11.307 | 11.329 |
| 9/16 -18 | 12.90 | 13.081 | 12.751 |
| 5/8 -18 | 14.50 | 14.681 | 14.351 |
| 3/4 -16 | 17.50 | 17.678 | 17.323 |
| 7/18 -14 | 20.50 | 20.675 | 20.270 |
| 1 -12 | 23.30 | 23.571 | 23.114 |
| 1-1/8 -12 | 26.50 | 26.746 | 26.289 |
| 1-14 -12 | 29.60 | 29.921 | 29.464 |
| 1-38 -12 | 32.80 | 33.096 | 32.639 |
| 1-1/2 -12 | 36.00 | 36.271 | 35.814 |
American Coarse Thread
| Screw Tap(UNC) | Standard Diameter | Class 2 Tap Drill Size | |
| Maximum | Minimum | ||
| NO.1 -64(1.854) | 1.55 | 1.582 | 1.425 |
| NO.2 -56(2.184) | 1.80 | 1.871 | 1.695 |
| NO.3 -48(2.515) | 2.10 | 2.146 | 1.941 |
| NO.4 -40(2.845) | 2.30 | 2.385 | 2.157 |
| NO.5 -40(3.175) | 2.60 | 2.697 | 2.487 |
| NO.6 -32(3.505) | 2.80 | 2.895 | 2.642 |
| NO.8 -32(4.166) | 3.40 | 3.530 | 3.302 |
| NO.10 -24(4.826) | 3.90 | 3.962 | 3.683 |
| NO.12 -24(5.486) | 4.50 | 4.597 | 4.344 |
| 1/4 -20 | 5.10 | 5.257 | 4.979 |
| 5/16 -18 | 6.60 | 6.731 | 6.401 |
| 3/8 -16 | 8.00 | 8.153 | 7.798 |
| 7/16 -14 | 9.40 | 9.550 | 9.144 |
| 1/2 -13 | 10.90 | 11.023 | 10.592 |
| 9/16 -12 | 12.20 | 12.446 | 11.989 |
| 5/8 -11 | 13.60 | 13.868 | 13.386 |
| 3/4 -10 | 16.60 | 16.840 | 16.307 |
| 7/8 -9 | 19.60 | 19.761 | 19.177 |
| 1 -8 | 22.30 | 22.606 | 21.971 |
| 1-1/8 -7 | 25.00 | 25.349 | 24.638 |
| 1-1/4 -7 | 28.20 | 28.524 | 27.813 |
| 1-3/8 -6 | 30.80 | 31.115 | 30.353 |
| 1-1/2 -6 | 34.00 | 34.290 | 33.528 |
| 1-3/4 -5 | 39.50 | 39.827 | 38.964 |
| 2 -4-1/2 | 45.20 | 45.593 | 44.679 |
American Extra Fine Thread
| Screw Tap(UNEF) | Standard Diameter | Class 2 Tap Drill Size | |
| Maximum | Minimum | ||
| NO.12 -32 | 4.70 | 4.826 | 4.623 |
| 1/4 -32 | 5.60 | 5.689 | 5.487 |
| 5/16 -32 | 7.10 | 7.264 | 7.087 |
| 3/8 -32 | 8.7 | 8.864 | 8.662 |
| 7/16 -28 | 10.20 | 10.337 | 10.135 |
| 1/2 -28 | 11.80 | 11.938 | 11.710 |
| 9/16 -24 | 13.20 | 13.385 | 13.132 |
| 5/18 -24 | 14.80 | 14.968 | 14.732 |
| 3/4 -20 | 17.80 | 17.957 | 17.679 |
| 7/8 -20 | 21.00 | 21.132 | 20.854 |
| 1 -20 | 24.10 | 24.307 | 24.029 |
American Pipe Thread
| Screw Tap | Drill Diameter | ||
| NPT | NPS | ||
| When Using a Tap | Without Using a Tap | ||
| 1/16 -27 | 5.94 | 6.15 | 6.35 |
| 1/8 -27 | 8.33 | 8.43 | 8.74 |
| 1/4 -18 | 10.72 | 11.13 | 11.13 |
| 3/8 -18 | 14.27 | 14.27 | 14.68 |
| 1/2 -14 | 17.48 | 17.86 | 18.26 |
| 3/4 -14 | 22.63 | 23.01 | 23.42 |
| 1 -11-1/2 | 28.58 | 28.98 | 29.36 |
| 1-1/4 -11-12 | 37.31 | 37.69 | 38.10 |
| 1-1/2 -11-1/2 | 43.26 | 43.66 | 44.45 |
| 2 -11-1/2 | 55.17 | 55.58 | 58.36 |
American Forced Thread Tapping Drill Diameter
| American Tap Size | Precision | Maximum | Minimum |
| 1 -64UNC | G5 | 1.76 | 1.68 |
| 2 -56 | G4 | 2.04 | 1.96 |
| 3 -48 | G4 | 2.35 | 2.25 |
| 4 -40 | G5 | 2.64 | 2.54 |
| 5 -40 | G5 | 2.97 | 2.87 |
| 6 -32 | G5 | 3.22 | 3.11 |
| 8 -32 | G6 | 3.89 | 3.78 |
| 10 -24 | G6 | 4.44 | 4.30 |
| 12 -24 | G6 | 5.07 | 4.96 |
| 1/4″ -20 | G7 | 5.86 | 5.73 |
| 5/16″ -18 | G7 | 7.38 | 7 23 |
| 3/8″ -16 | G7 | 8.89 | 8.72 |
| 7/16″ -14 | G8 | 10.40 | 10.02 |
| 1/2″ -13 | G8 | 11.92 | 11.70 |
| 0 -80UNF | G5 | 14.5 | 1.39 |
| 1 -72 | G5 | 1.77 | 1.70 |
| 2 -64 | G4 | 2.06 | 1.98 |
| 3 -56 | G4 | 2.37 | 2.29 |
| 4 -48 | G5 | 2.68 | 2.59 |
| 5 -44 | G5 | 2.99 | 2 90 |
| 6 -40 | G5 | 3.29 | 3.19 |
| 8 -36 | G5 | 3.91 | 3.81 |
| 10 -32 | G6 | 4.53 | 4.44 |
| 12 -20 | G6 | 5.13 | 5.03 |
| 1/4″ -28 | G7 | 6.00 | 5.91 |
| 5/16″ -24 | G7 | 7.53 | 7.42 |
| 3/8″ -24 | G7 | 9.10 | 8.99 |
| 7/16″ -20 | G8 | 10.62 | 10.48 |
| 1/2″ -20 | G8 | 12.20 | 12.06 |
Metric Forced Thread Tapping Drill Diameter
| Metric Tap Size | Precision | Maximum | Minimum |
| M1.0x0.25 | G4 | 0.92 | 0.89 |
| M1.2 x0.25 | G4 | 1.12 | 1.09 |
| M1.4 x0.3 | G4 | 1.30 | 1.26 |
| M1.6 x0.35 | G4 | 1.47 | 1.42 |
| M1.7 x0.35 | G4 | 1.57 | 1.52 |
| M1.8 x0.35 | G4 | 1.67 | 1.62 |
| M2.0 x0.4 | G4 | 1.84 | 1.79 |
| M2.2 x0.45 | G5 | 2.04 | 1.97 |
| M2.3 x0.4 | G4 | 2.14 | 2.09 |
| M2.5 x0.45 | G5 | 2.34 | 2.27 |
| M2.6 x0.45 | G5 | 2.44 | 2.37 |
| M3.0x0.5 | G5 | 2.82 | 2.75 |
| M3.5×0.6 | G5 | 3.27 | 3.19 |
| M4.0 x0.7 | G6 | 3.72 | 3.65 |
| M5.0 x0.8 | G6 | 4.67 | 4.59 |
| M6.0x1.0 | G7 | 5.59 | 5.49 |
| M7.0x1.0 | G7 | 6.59 | 6.49 |
| M8.0x1.25 | G7 | 7.49 | 7.36 |
| M10x1.5 | G7 | 9.34 | 9.22 |
| M10 x1.25 | G7 | 9.49 | 9.35 |
| M12x 1.75 | G8 | 11.23 | 11.09 |
| M12 x 1.25 | G9 | 11.50 | 11.36 |
Inch Standard Thread
| Inch Tap Size | Drill Diameter | |
| Hard Material | Soft Material | |
| W1/8 -40 | 2.65 | 2.60 |
| W5/32 -32 | 3.25 | 3.20 |
| W3/16 -24 | 3.75 | 3.70 |
| W1/4 -20 | 5.10 | 5.00 |
| W5/16 -18 | 6.60 | 6.50 |
| W3/8 -16 | 8.00 | 7.90 |
| W7/16 -14 | 9.40 | 9.30 |
| W1/2 -12 | 10.70 | 10.50 |
| W9/16 -12 | 12.30 | 12.00 |
| W5/8 -11 | 13.70 | 13.50 |
| W3/4 -10 | 16.70 | 16.50 |
| W7/8 -9 | 19.50 | 19.30 |
| W1 -8 | 22.40 | 22.00 |
| W1-1/8 -7 | 25.00 | 24.80 |
| W1-1/4 -7 | 28.30 | 28.00 |
Inch Standard Electrical Thread
| Inch Tap Size | Drill Diameter |
| 2BA | 4.0-4.2 |
| 3BA | 3.4-3.6 |
| 4BA | 3.0-3.2 |
| 5BA | 2.7-2.8 |
| 6BA | 2.4-2.5 |
Inch Standard Pipe Thread
| Inch Tap Size （New Specification PR） | Standard Diameter | Maximum | Minimum |
| 1/16 -28 | 6.5 | 6.632 | 6.490 |
| 1/8 -28 | 8.5 | 8.637 | 8.495 |
| 1/4 -19 | 11.4 | 11.549 | 11.341 |
| 3/8 -19 | 14.9 | 15.045 | 14.846 |
| 1/2 -14 | 18.6 | 18.773 | 18.489 |
| 3/4 -14 | 24.0 | 24.259 | 23.975 |
| 1 -11 | 30.2 | 30.47 | 30.110 |
| 11/4 -11 | 38.8 | 39.133 | 38.771 |
| 1 1/2 -11 | 44.7 | 45.026 | 44.664 |
| 2 -11 | 56.5 | 56.837 | 56.475 |
| Inch Tap Size （New Specification G） | Standard Diameter | Maximum | Minimum |
| 1/16 -28 | 6.7 | 6.843 | 6.561 |
| 1/8 -28 | 8.7 | 8.848 | 8.566 |
| 1/4 -19 | 11.7 | 11.890 | 11.445 |
| 3/8 -19 | 15.2 | 15.395 | 14.950 |
| 1/2 -14 | 19.0 | 19.172 | 18.631 |
| 5/8 -14 | 21.0 | 21.128 | 20.587 |
| 3/4 -14 | 24.5 | 24.658 | 24.117 |
| 7/8 -14 | 28.2 | 28.418 | 27.877 |
| 1 -11 | 30.6 | 30.931 | 30.291 |
| 1 1/8 -11 | 35.2 | 35.579 | 34.939 |
| 1 1/4 -11 | 39.2 | 39.592 | 38.952 |
| 1 1/2 -11 | 45.0 | 45.485 | 44.845 |
| 13/4 -11 | 51.0 | 51.428 | 50.788 |
| 2 -11 | 57.0 | 57.296 | 56.656 |
| PT Specification (New Specification RC) | Standard Diameter | Minimum Inside Diameter of Parent Thread in Minimum Effective Thread Length | Minimum Inside Diameter of Parent Thread in Standard Length | |
| When Using a Tap | Without Using a Tap | |||
| 1/16 -28 | 6.1 | 6.2 | 6.244 | 6.384 |
| 1/8 -28 | 8.1 | 8.2 | 8.249 | 8.388 |
| 1/4 -19 | 10.7 | 11.0 | 10.962 | 11.174 |
| 3/8 -19 | 914.2 | 14.5 | 14.448 | 14.658 |
| 1/2 -14 | 17.6 | 18.0 | 17.979 | 18.263 |
| 3/14 -14 | 23.0 | 23.5 | 23.378 | 23.663 |
| 1 -11 | 29.0 | 29.5 | 29.459 | 29.822 |
| 11/4 -11 | 37.5 | 38.0 | 37.976 | 38.339 |
| 11/12 -11 | 43.4 | 44.0 | 43.869 | 44.232 |
| 2 -11 | 54.9 | 55.5 | 55.412 | 55.844 |
Related resources: Thread Size Chart (inch/mm)
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FAQ
What is a tap for a screw?
Specifically, a tap serves the purpose of cutting or shaping the female component of a screw-and-nut pairing (for instance, a nut).
How do I know what size hole to drill for tapping?
To determine the correct hole size for tapping, refer to a tap drill size chart based on the thread size and type of tap you’re using. Consider the material being tapped and aim for at least 1 to 1.5 times the diameter of the screw’s major diameter for proper thread engagement.
What are the different types of tap screws?
Tap screws come in various types, including machine screws, tapping screws, wood screws, sheet metal screws, thread-forming screws, thread-cutting screws, and machine screws with tapped holes.
Tagged: CNC Machining Guide
This article was written by engineers from the BOYI team. Fuquan Chen is a professional engineer and technical expert with 20 years of experience in rapid prototyping, mold manufacturing, and plastic injection molding.
