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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