Tap Drill for Machine Screws (in)

Written by Matt Milbury on . Posted in Thread Datasheets

  • This chart show what size drill bit to use with a tap.
  • Drill size recommendations are for 70-75% thread height.
  • Drills produce a hole slightly larger then their normal size.

Tap Drill for Machine Screws (in) Datasheet

Pipe

Size

Threads

per

Inch

Drill

Size

Drill

Size

Decimal

1/4 20 7 0.2010
1/4 28 3 0.2130
5/16 18 F 0.2570
5/16 24 I 0.2720
3/8 16 5/16 0.3125
3/8 -24 Q 0.3320
7/16 14 U 0.3680
7/16 20 25/64 0.3906
1/2 13 27/64 0.4219
1/2 20 29/64 0.4531
9/16 12 31/64 0.4844
9/16 18 33/64 0.5156
5/8 11 17/32 0.5312
5/8 18 37/64 0.5781
3/4 10 21/32 0.6562
3/4 16 11/16 0.6875
7/8 9 49/64 0.7656
7/8 14 13/16 0.8125
1 8 7/8 0.8750
1 12 59/64 0.9219
1-1/8 7 63/64 0.9844
1-1/8 12 1-3/64 1.0469
1-1/4 7 1-7/64 1.1094
1-1/4 12 1-11/64 1.1719
1-3/8 6 1-11/32 1.2188
1-3/8 12 1-19/64 1.2969
1-1/2 6 1-11/32 1.3438
1-1/2 12 1-27/64 1.4219
Pipe SizeThreads

per Inch

Drill SizeDrill Size

Decimal