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Engineering, Design, and Manufacturing Knowledge

Metric and inches Tap drill size chart

METRIC COARSE TAP SIZE
TAP SIZE DRILL SIZE
M1 x .25 .75mm
1.2 x .25 .95
2 x .4 1.6
2.5 x .45 2.05
3 x .5 2.5
3.5 x .6 2.9
4 x .7 3.3
5 x .8 4.2
6 x 1 5
8 x 1.25 6.8
10 x 1.5 8.5
12 x 1.75 10.2
14 x 2 12
16 x 2 14
18 x 2.5 15.5
20 x 2.5 17.5
22 x 2.5 19.5
24 x 3 21
30 x 3.5 26.5
33 x 3.5 29.5
36 x 4 32

 
METRIC FINE TAP SIZE
TAP SIZE DRILL SIZE
M4 x .35 3.6mm
4 x .5 3.5
5 x .5 4.5
6 x .5 5.5
7 x .75 6.25
8 x .5 7.5
8 x 1 7
9 x 1 8
10 x .75 9.25
10 x 1.25 8.8
12 x 1.5 10.5
14 x 1.5 12.5
16 x 1.5 14.5
18 x 1 17
20 x 1.5 18.5
22 x 1.5 20.5
24 x 1.5 22.5
26 x 1.5 24.5
27 x 1.5 25.5
28 x 1.5 26.5
30 x 1.5 28.5
30 x 2 28
33 x 2 31
36 x 3 33
INCH SIZES - NATIONAL COARSE
TAP SIZE DRILL SIZE
#0-80 3/64"
#1-64 #53
#2-56 #51
#3-48 5/64"
#4-40 #43
#5-40 #39
#6-32 #36
#8-32 #29
#10-24 #25
#12-24 #17
1/4-20 #7
3/8-16 5/16
1/2-13 27/64
9/16-12 31/64
5/8-11 17/32
3/4-10 21/32
7/8-9 49/64
1"-8 7/8
1-1/8-7 63/64
1-1/4-7 1-7/64
1-1/2-6 1-11/32
1-3/4-5 1-35/64
2"-4-1/2 1-25/32
INCH SIZES - NATIONAL FINE
TAP SIZE DRILL SIZE
#1-72 #53
#2-64 #50
#3-56 #46
#4-48 #42
#5-44 #37
#6-40 #33
#8-36 #29
#10-32 #21
#12-28 #15
1/4-28 #3
1/2-20 29/64
9/16-18 33/64
5/8-18 37/64
3/4-16 11/16
7/8-14 13/16
1"-12 15/16
1-1/8-12 1-3/64
1-1/4-12 1-11/64
1-1/2-12 1-27/64
1-3/4-12 1-43/64
2"-12 1-59/64
TAPER PIPE SIZES - NPT
TAP SIZE DRILL SIZE
1/4-18 7/16
3/8-18 37/64
1/2-14 23/32
3/4-14 59/64
1"-11-1/2 1-5/32
1-1/4-11-1/2 1-1/2
1-1/2-11-1/2 1-47/64
2"-11-1/2 2-7/32
2-1/2-8 2-5/8
3"-8 3-1/4
3-1/2-8 3-3/4
4"-8 4-1/4
STRAIGHT PIPE SIZES - NPS
TAP SIZE DRILL SIZE
1/4-18 29/64
3/8-18 19/32
1/2-14 47/64
3/4-14 15/16
1"-11-1/2 1-3/16
1-1/4-11-1/2 1-33/64
1-1/2-11-1/2 1-3/4
2"-11-1/2 2-7/32
2-1/2-8 2-21/32
3"-8 3-9/32
3-1/2-8 3-25/32
4"-8 4-9/32