Tap and Drill Bit Size Chart

Tap and Drill Bit Size Chart

The charts below show you what size drill bit to use with a tap.
Tap sizes are shown as hole size – threads per inch.  Example 1/4-20 = 1/4″ hole, 20 threads per inch.

Imperial / SAE tap and drill bit size table

Tap Fractional Drill Bit Number Drill Bit Letter Drill Bit
0-80 3/64
1-64 53
2-56 50
3-48 47
4-40 3/32 43
5-40 38
6-32 7/64 35
8-32 29
10-24 5/32 25
10-32 5/32 21
12-24 11/64 16
1/4-20 13/64 7
1/4-28 7/32 3
5/16-18 17/64 F
5/16-24 I
3/8-16 5/16
3/8-24 21/64 Q
7/16-14 23/64 U
7/16-20 25/64
1/2-13 27/64
1/2-20 29/64
9/16-12 31/64
9/16-18 33/64
5/8-11 17/32
5/8-18 37/64
3/4-10 21/32
3/4-16 11/16
Drill sizes are for 75% depth of thread.

Metric tap and drill bit size table
Tap sizes are shown as hole size – threads per mm (millimeter).  Example 6mm-1.0 = 6mm hole, 1 threads per mm.

Tap Metric Drill Imperial Drill
3 mm x 0.6 2.5 mm
4 mm x 0.7 3.4 mm
5 mm x 0.8 4.3 mm
6 mm x 1.0 5.2 mm
7 mm x 1.0 6.1 mm 15/64
8 mm x 1.25 6.9 mm 17/64
8 mm x 1.0 7.1 mm
10 mm x 1.5 8.7 mm
10 mm x 1.25 8.9 mm 11/32
10 mm x 1.0 9.1 mm
12 mm x 1.75 10.5 mm
12 mm x 1.5 10.7 mm 27/64
14 mm x 2.0 12.2 mm
14 mm x 1.5 12.7 mm
16 mm x 2.0 14.2 mm 35/64
16 mm x 1.5 14.7 mm
Drill sizes are for 75% depth of thread.

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