INCH TAP DRILL SIZES

INCH TAP DRILL SIZES
Recommended tap drill sizes (for approx. 75% thread)

 INCH SIZES - NATIONAL COARSE
  INCH SIZES - NATIONAL FINE
 TAP SIZE
 
 #1-64
#2-56
#3-48
#4-40
#5-40
#6-32
#8-32
#10-24
#12-24
1/4-20
5/16-18
3/8-16
7/16-14
1/2-13
9/16-12
5/8-11
3/4-10
7/8-9
1"-8
1-1/8-7
1-1/4-7
1-1/2-6
1-3/4-5
2"-4-1/2
DRILL SIZE
 
 #53
#51
5/64"
#43
#39
#36
#29
#25
#17
#7
F
5/16
U
27/64
31/64
17/32
21/32
49/64
7/8
63/64
1-7/64
1-11/32
1-35/64
1-25/32
TAP SIZE
 
 #0-80
#1-72
#2-64
#3-56
#4-48
#5-44
#6-40
#8-36
#10-32
#12-28
1/4-28
5/16-24
3/8-24
7/16-20
1/2-20
9/16-18
5/8-18
3/4-16
7/8-14
1"-14
1-1/8-12
1-1/4-12
1-1/2-12
1-3/4-12
2"-12
DRILL SIZE
 3/64"
#53
#50
#46
#42
#37
#33
#29
#21
#15
#3
I
Q
W
29/64
33/64
37/64
11/16
13/16
15/16
1-3/64
1-11/64
1-27/64
1-43/64
1-59/64

METRIC COARSE SIZES
METRIC FINE SIZES

TAP SIZE

1mm x .25
1.1 x .25
1.2 x .25
1.4 x .3
1.6 x .35
1.7 x .35
1.8 x .35
2 x .4 
2.2 x .45
2.5 x .45
3 x .5
3.5 x .6
4 x .7
4.5 x .75
5 x .8
6 x 1 
7 x 1
8 x 1.25
9 x 1.25
10 x 1.5
11 x 1.5
12 x 1.75 
14 x 2
16 x 2 
18 x 2.5 
20 x 2.5
22 x 2.5 
24 x 3 
27 x 3
30 x 3.5
33 x 3.5
36 x 4
39 x 4
DRILL SIZE

.75mm 
.85
.95
1.1
1.25
1.3 
1.45
1.6
1.75
2.05
2.5
2.9
3.3
3.7
4.2
5 
6
6.8
7.8
8.5
9.5
10.2
12
14
15.5
17.5
19.5
21
24
26.5
29.5
32
35 
TAP SIZE 

4 mm x .35
4 x .5
5 x .5
6 x .5
6 x .75
7 x .75
8 x .5
8 x .75
8 x 1
9 x 1 
10 x .75
10 x 1
10 x 1.25
11 x 1 
12 x .75 
12 x 1
12 x 1.5
14 x 1 
14 x 1.25
14 x 1.5
16 x 1
16 x 1.5
18 x 1
18 x 2 
20 x 1
20 x 1.5
20 x 2
22 x 1
22 x 1.5
22 x 2
24 x 1.5
24 x 2
26 x 1.5
27 x 1.5
27 x 2
28 x 1.5
30 x 1.5
30 x 2
33 x 2
36 x 3
39 x 3
DRILL SIZE

3.6mm
3.5
4.5
5.5
5.25
6.25
7
7.25
7.5
8
9.25
9
8.8
10
11.25
11
10.5
13
12.8
12.5
15
14.5
17
16
19
18.5
18
21
20.5
20
22.5
22
24.5
25.5
25 
26.5
28.5
28
31
33
36 

Handy Helpers!
 Tap Drill Sizes (inch) for a 75% Thread
 In general, you can find the tap-drill for any size 60 degree thread, subtract one pitch length from the major diameter.
 Formula: Major Dia. minus One Pitch Length equals tap-drill size
 English Example for 3/8-16 thread: .375 - .0625 = .3125 tap-drill (5/16)
 Metric Example for M6 X 1 thread: 6mm - 1mm = 5mm tap-drill