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Screw Tap Drill Size Chart (Metric/Inch/US)

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 SizeStandard DiameterClass 2 Tap Drill Size
MaximumMinimum
M1.0x0.250.750.7850.729
M1.1×0.250.850.8850.829
M1.2×0.250.950.9850.929
M1.4×0.31.101.1421.075
M1.6×0.351.451.5211.421
M2.0x0.41.601.6791.567
M2.2×0.451.751.8381.713
M2.3×0.41.901.9791.867
M2.5×0.452.102.1382.013
M2.6×0.452.202.2382.113
M3.0x0.52.502.5992.459
M3.5×0.62.903.0102.850
M4.0x0.73.303.4223.242
M4.5×0.753.803.8783.688
M5.0x0.84.204.3344.134
M6.0x1.05.005.1534.917
M7.0x1.06.006.1535.917
M8.0x1.256.806.9126.647
M9.0x1.257.807.9127.647
M10x1.58.508.6768.376
M11x1.59.509.6769.376
M12x1.7510.3010.44110.106
M14x2.012.0012.21011.835
M16×2.014.0014.21013.835
M18x2.515.5015.74415.294
M20x2.517.5017.74417.294
M22×2.519.5019.74419.294
M24x3.021.0021.25220.752
M27x3.024.0024.25223.752
M30x3.526.5026.77126.211
M33x3.529.5029.77129.221
M36x4.032.0032.27031.670
M39x4.035.0035.27034.670

Metric Fine Thread

Metric Tap SizeStandard DiameterClass 2 Tap Drill Size
Maximum
Minimum
M1.0x0.20.800.8210.783
M1.1×0.20.900.9210.883
M1.2×0.21.001.0210.983
M1.4×0.21.201.2211.183
M1.6×0.21.401.4211.383
M1.7×0.21.501.5211.483
M1.8×0.21.601.6211.583
M2.0x0.251.751.7851.729
M2.2×0.251.951.9851.929
M2.3×0.252.052.0612.001
M2.5×0.352.202.2212.121
M2.6×0.352.202.2462.186
M3.0x0.352.702.7212.621
M3.5×0.353.203.2213.121
M4.0x0.53.503.5993.459
M4.5×0.54.004.0993.959
M5.0x0.54.504.5994.459
M5.5×0.55.005.0994.959
M6.0x0.755.305.3785.188
M6.0x0.55.505.5505.400
M7.0x0.756.306.3786.188
M7.0x0.56.506.5506.400
M8.0x1.07.007.1536.917
M8.0x0.757.307.3787.188
M8.0x0.57.507.5207.400
M9.0x1.08.008.1537.917
M9.0x0.758.308.3788.188
M10x1.258.808.9128.647
M10x1.09.009.1538.917
M10x0.759.309.3789.188
M10x0.59.509.5209.400
M11x1.010.0010.1539.917
M11x0.7510.3010.37810.188
M12x1.510.5010.67610.376
M12x1.2510.8010.91210.647
M12x1.011.0011.15310.917
M12x0.511.5011.52011.400
M14x1.512.5012.67612.376
M14x1.013.0013.15312.917
M15x1.513.5013.67613.376
M15x1.014.0014.15313.917
M16x1.514.5014.67614.376
M16x1.015.0015.15314.917
M17x1.515.5015.67615.376
M17x1.016.0016.15315.917
M18x2.016.0016.21015.835
M18x1.516.5016.67616.376
M18x1.017.0017.15316.917
M20x2.018.0018.21017.835
M20x1.518.5018.67618.376
M20x1.019.0019.15318.917
M22x2.020.0020.21019.835
M22x1.520.5020.67620.376
M22x1.021.0021.15320.917
M24x2.022.0022.21021.835
M24x1.522.5022.67622.376
M24x1.023.0023.15322.917
M25×2.023.0023.21022.835
M25x1.523.5023.67023.370
M25x1.024.0024.15323.917
M26x1.524.5024.67624.376
M27x2.025.0025.21024.835
M27x1.525.5025.67625.376
M27x1.026.0026.15325.917
M28x2.026.0026.21025.835
M28x1.526.5026.67626.376
M28x1.027.0027.15326.917
M30x3.027.0027.25226.752
M30x2.028.0028.21027.835
M30x1.528.5028.67628.376
M30x1.029.0029.15328.917
M32x2.030.0030.21029.835
M32x1.530.5030.67630.376
M33x3.030.0030.25229.752
M33x2.031.0031.21030.835
M33x1.531.5031.67631.376
M35x1.533.5033.67633.376
M36x3.033.0033.25232.752
M36x2.034.0034.21033.835
M36x1.534.5034.67634.376

American Fine Thread

Screw Tap Size(UNF)Standard DiameterClass 2 Tap Drill Size
MaximumMinimum
NO.O  -80(1524)1.251.3051.182
NO.1  -72(1.854)1.551.6121.474
NO.2  -64(2184)1.851.9121.756
NO.3  -56(2515)2.102.1972.025
NO.4  -48(2845)2.402.4582.271
NO.5  -44(3715)2.702.7402.551
NO.6  -40(3.505)2.903.0222.820
NO.8  -36(4.166)3.503.6063.404
NO.10  -32(4.826)4.104.1653.963
NO.12  -28(5.486)4.604.7244.496
1/4  -285.505.5885.360
5/16  -246.907.0356.782
3/8  -248.508.6368.382
7/16  -209.9010.0339.729
1/2  -2011.5011.30711.329
9/16  -1812.9013.08112.751
5/8  -1814.5014.68114.351
3/4  -1617.5017.67817.323
7/18  -1420.5020.67520.270
1  -1223.3023.57123.114
1-1/8  -1226.5026.74626.289
1-14  -1229.6029.92129.464
1-38  -1232.8033.09632.639
1-1/2  -1236.0036.27135.814

American Coarse Thread

Screw Tap(UNC)Standard DiameterClass 2 Tap Drill Size
MaximumMinimum
NO.1  -64(1.854)1.551.5821.425
NO.2  -56(2.184)1.801.8711.695
NO.3  -48(2.515)2.102.1461.941
NO.4  -40(2.845)2.302.3852.157
NO.5  -40(3.175)2.602.6972.487
NO.6  -32(3.505)2.802.8952.642
NO.8  -32(4.166)3.403.5303.302
NO.10  -24(4.826)3.903.9623.683
NO.12  -24(5.486)4.504.5974.344
1/4  -205.105.2574.979
5/16  -186.606.7316.401
3/8  -168.008.1537.798
7/16  -149.409.5509.144
1/2  -1310.9011.02310.592
9/16 -1212.2012.44611.989
5/8  -1113.6013.86813.386
3/4  -1016.6016.84016.307
7/8  -919.6019.76119.177
1  -822.3022.60621.971
1-1/8  -725.0025.34924.638
1-1/4  -728.2028.52427.813
1-3/8  -630.8031.11530.353
1-1/2  -634.0034.29033.528
1-3/4  -539.5039.82738.964
2  -4-1/245.2045.59344.679

American Extra Fine Thread

Screw Tap(UNEF)Standard DiameterClass 2 Tap Drill Size
MaximumMinimum
NO.12  -324.704.8264.623
1/4  -325.605.6895.487
5/16 -327.107.2647.087
3/8  -328.78.8648.662
7/16  -2810.2010.33710.135
1/2  -2811.8011.93811.710
9/16  -2413.2013.38513.132
5/18  -2414.8014.96814.732
3/4  -2017.8017.95717.679
7/8  -2021.0021.13220.854
1  -2024.1024.30724.029

American Pipe Thread

Screw TapDrill Diameter
NPTNPS
When Using a TapWithout Using a Tap
1/16  -275.946.156.35
1/8  -278.338.438.74
1/4  -1810.7211.1311.13
3/8  -1814.2714.2714.68
1/2  -1417.4817.8618.26
3/4  -1422.6323.0123.42
1  -11-1/228.5828.9829.36
1-1/4  -11-1237.3137.6938.10
1-1/2  -11-1/243.2643.6644.45
2  -11-1/255.1755.5858.36

American Forced Thread Tapping Drill Diameter

American Tap SizePrecisionMaximumMinimum
1  -64UNCG51.761.68
2  -56G42.041.96
3  -48G42.352.25
4  -40G52.642.54
5  -40G52.972.87
6  -32G53.223.11
8  -32G63.893.78
10  -24G64.444.30
12  -24G65.074.96
1/4″  -20G75.865.73
5/16″  -18G77.387 23
3/8″  -16G78.898.72
7/16″  -14G810.4010.02
1/2″  -13G811.9211.70
0  -80UNFG514.51.39
1  -72G51.771.70
2  -64G42.061.98
3  -56G42.372.29
4  -48G52.682.59
5  -44G52.992 90
6  -40G53.293.19
8  -36G53.913.81
10  -32G64.534.44
12  -20G65.135.03
1/4″  -28G76.005.91
5/16″  -24G77.537.42
3/8″  -24G79.108.99
7/16″  -20G810.6210.48
1/2″  -20G812.2012.06

Metric Forced Thread Tapping Drill Diameter

Metric Tap SizePrecisionMaximumMinimum
M1.0x0.25G40.920.89
M1.2 x0.25G41.121.09
M1.4 x0.3G41.301.26
M1.6 x0.35G41.471.42
M1.7 x0.35G41.571.52
M1.8 x0.35G41.671.62
M2.0 x0.4G41.841.79
M2.2 x0.45G52.041.97
M2.3 x0.4G42.142.09
M2.5 x0.45G52.342.27
M2.6 x0.45G52.442.37
M3.0x0.5G52.822.75
M3.5×0.6G53.273.19
M4.0 x0.7G63.723.65
M5.0 x0.8G64.674.59
M6.0x1.0G75.595.49
M7.0x1.0G76.596.49
M8.0x1.25G77.497.36
M10x1.5G79.349.22
M10 x1.25G79.499.35
M12x 1.75G811.2311.09
M12 x 1.25G911.5011.36

Inch Standard Thread

Inch Tap SizeDrill Diameter
Hard MaterialSoft Material
W1/8  -402.652.60
W5/32   -323.253.20
W3/16  -243.753.70
W1/4  -205.105.00
W5/16  -186.606.50
W3/8  -168.007.90
W7/16  -149.409.30
W1/2  -1210.7010.50
W9/16  -1212.3012.00
W5/8  -1113.7013.50
W3/4  -1016.7016.50
W7/8  -919.5019.30
W1  -822.4022.00
W1-1/8   -725.0024.80
W1-1/4   -728.3028.00

Inch Standard Electrical Thread

Inch Tap SizeDrill Diameter
2BA4.0-4.2
3BA3.4-3.6
4BA3.0-3.2
5BA2.7-2.8
6BA2.4-2.5

Inch Standard Pipe Thread

Inch Tap Size
(New Specification PR)
Standard DiameterMaximumMinimum
1/16   -286.56.6326.490
1/8  -288.58.6378.495
1/4   -1911.411.54911.341
3/8  -1914.915.04514.846
1/2  -1418.618.77318.489
3/4   -1424.024.25923.975
1   -1130.230.4730.110
11/4  -1138.839.13338.771
1 1/2  -1144.745.02644.664
2   -1156.556.83756.475
Inch Tap Size
(New Specification G)
Standard DiameterMaximumMinimum
1/16   -286.76.8436.561
1/8  -288.78.8488.566
1/4  -1911.711.89011.445
3/8  -1915.215.39514.950
1/2  -1419.019.17218.631
5/8  -1421.021.12820.587
3/4  -1424.524.65824.117
7/8  -1428.228.41827.877
1  -1130.630.93130.291
1 1/8   -1135.235.57934.939
1 1/4   -1139.239.59238.952
1 1/2   -1145.045.48544.845
13/4   -1151.051.42850.788
2  -1157.057.29656.656

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.


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