National Pipe Thread (NPT) Tap Drill Size

 

Standard NPT Tap Drill Sizes

NPT Size
 Tap Drill Size (in.)
Decimal Equivalent (in.)
1/16 – 27
“C”
0.242
1/8 – 27
“Q” 
0.332
1/4 – 18
7/16
0.438
3/8 – 18
9/16
0.562
1/2 – 14
45/64
0.703
3/4 – 14
29/32
0.906
1.0 – 111/2
19/64
1.141
11/4 – 111/2
131/64
1.484
11/2 – 111/2
123/32
1.719
2.0 – 111/2
23/16
2.188
21/2 – 8
239/64
2.609
3.0 – 8
315/64
3.234

 
Metric Tap Drill Sizes
Standard UNC Tap Drill Sizes
Standard UNF Tap Drill Sizes

Drill Size Chart – Standard Fractional, Letter, Gauge and Metric

Drill size Diameter (in) Diameter (mm)
#107 0.0019 0.0483
0.05 mm 0.0020 0.0500
#106 0.0023 0.0584
#105 0.0027 0.0686
#104 0.0031 0.0787
#103 0.0035 0.0889
#102 0.0039 0.0991
0.1 mm 0.0039 0.1000
#101 0.0043 0.1092
#100 0.0047 0.1194
#99 0.0051 0.1295
#98 0.0055 0.1397
#97 0.0059 0.1499
#96 0.0063 0.1600
#95 0.0067 0.1702
#94 0.0071 0.1803
#93 0.0075 0.1905
0.2 mm 0.0079 0.2000
#92 0.0079 0.2007
#91 0.0083 0.2108
#90 0.0087 0.2210
#89 0.0091 0.2311
#88 0.0095 0.2413
#87 0.0100 0.2540
#86 0.0105 0.2667
#85 0.0110 0.2794
#84 0.0115 0.2921
0.3 mm 0.0118 0.3000
#83 0.0120 0.3048
#82 0.0125 0.3175
#81 0.0130 0.3302
#80 0.0135 0.3429
#79 0.0145 0.3680
1/64 in 0.0156 0.3969
0.4 mm 0.0158 0.4000
#78 0.0160 0.4064
#77 0.0180 0.4572
0.5 mm 0.0197 0.5000
#76 0.0200 0.5080
#75 0.0210 0.5334
#74 0.0225 0.5715
0.6 mm 0.0236 0.6000
#73 0.0240 0.6096
#72 0.0250 0.6350
#71 0.0260 0.6604
0.7 mm 0.0276 0.7000
#70 0.0280 0.7112
#69 0.0292 0.7417
#68 0.0310 0.7874
1/32 in 0.0313 0.7938
0.8 mm 0.0315 0.8000
#67 0.0320 0.8128
#66 0.0330 0.8382
#65 0.0350 0.8890
0.9 mm 0.0354 0.9000
#64 0.0360 0.9144
#63 0.0370 0.9398
#62 0.0380 0.9652
#61 0.0390 0.9906
1 mm 0.0394 1.0000
#60 0.0400 1.0160
#59 0.0410 1.0414
#58 0.0420 1.0668
#57 0.0430 1.0922
1.1 mm 0.0433 1.1000
#56 0.0465 1.1811
3/64 in 0.0469 1.1906
1.2 mm 0.0472 1.2000
1.3 mm 0.0512 1.3000
#55 0.0520 1.3208
#54 0.0550 1.3970
1.4 mm 0.0551 1.4000
1.5 mm 0.0591 1.5000
#53 0.0595 1.5113
1/16 in 0.0625 1.5875
1.6 mm 0.0630 1.6000
#52 0.0635 1.6129
1.7 mm 0.0669 1.7000
#51 0.0670 1.7018
#50 0.0700 1.7780
1.8 mm 0.0709 1.8000
#49 0.0730 1.8542
1.9 mm 0.0748 1.9000
#48 0.0760 1.9304
5/64 in 0.0781 1.9844
#47 0.0785 1.9939
2 mm 0.0787 2.0000
#46 0.0810 2.0574
#45 0.0820 2.0828
2.1 mm 0.0827 2.1000
#44 0.0860 2.1844
2.2 mm 0.0866 2.2000
#43 0.0890 2.2606
2.3 mm 0.0906 2.3000
#42 0.0935 2.3749
3/32 in 0.0938 2.3813
2.4 mm 0.0945 2.4000
#41 0.0960 2.4384
#40 0.0980 2.4892
2.5 mm 0.0984 2.5000
#39 0.0995 2.5273
#38 0.1015 2.5781
2.6 mm 0.1024 2.6000
#37 0.1040 2.6416
2.7 mm 0.1063 2.7000
#36 0.1065 2.7051
7/64 in 0.1094 2.7781
#35 0.1100 2.7940
2.8 mm 0.1102 2.8000
#34 0.1110 2.8194
#33 0.1130 2.8702
2.9 mm 0.1142 2.9000
#32 0.1160 2.9464
3 mm 0.1181 3.0000
#31 0.1200 3.0480
3.1 mm 0.1221 3.1000
1/8 in 0.1250 3.1750
3.2 mm 0.1260 3.2000
#30 0.1285 3.2639
3.3 mm 0.1299 3.3000
3.4 mm 0.1339 3.4000
#29 0.1360 3.4544
3.5 mm 0.1378 3.5000
#28 0.1405 3.5687
9/64 in 0.1406 3.5719
3.6 mm 0.1417 3.6000
#27 0.1440 3.6576
3.7 mm 0.1457 3.7000
#26 0.1470 3.7338
#25 0.1495 3.7973
3.8 mm 0.1496 3.8000
#24 0.1520 3.8608
3.9 mm 0.1535 3.9000
#23 0.1540 3.9116
5/32 in 0.1563 3.9688
#22 0.1570 3.9878
4 mm 0.1575 4.0000
#21 0.1590 4.0386
#20 0.1610 4.0894
4.1 mm 0.1614 4.1000
4.2 mm 0.1654 4.2000
#19 0.1660 4.2164
4.3 mm 0.1693 4.3000
#18 0.1695 4.3053
11/64 in 0.1719 4.3656
#17 0.1730 4.3942
4.4 mm 0.1732 4.4000
#16 0.1770 4.4958
4.5 mm 0.1772 4.5000
#15 0.1800 4.5720
4.6 mm 0.1811 4.6000
#14 0.1820 4.6228
#13 0.1850 4.6990
4.7 mm 0.1850 4.7000
3/16 in 0.1875 4.7625
4.8 mm 0.1890 4.8000
#12 0.1890 4.8006
#11 0.1910 4.8514
4.9 mm 0.1929 4.9000
#10 0.1935 4.9149
#9 0.1960 4.9784
5 mm 0.1969 5.0000
#8 0.1990 5.0546
5.1 mm 0.2008 5.1000
#7 0.2010 5.1054
13/64 in 0.2031 5.1594
#6 0.2040 5.1816
5.2 mm 0.2047 5.2000
#5 0.2055 5.2197
5.3 mm 0.2087 5.3000
#4 0.2090 5.3086
5.4 mm 0.2126 5.4000
#3 0.2130 5.4102
5.5 mm 0.2165 5.5000
7/32 in 0.2188 5.5563
5.6 mm 0.2205 5.6000
#2 0.2210 5.6134
5.7 mm 0.2244 5.7000
#1 0.2280 5.7912
5.8 mm 0.2284 5.8000
5.9 mm 0.2323 5.9000
A 0.2340 5.9436
15/64 in 0.2344 5.9531
6 mm 0.2362 6.0000
B 0.2380 6.0452
6.1 mm 0.2402 6.1000
C 0.2420 6.1468
6.2 mm 0.2441 6.2000
D 0.2460 6.2484
6.3 mm 0.2480 6.3000
1/4 in 0.2500 6.3500
E 0.2500 6.3500
6.4 mm 0.2520 6.4000
6.5 mm 0.2559 6.5000
F 0.2570 6.5278
6.6 mm 0.2598 6.6000
G 0.2610 6.6294
6.7 mm 0.2638 6.7000
17/64 in 0.2656 6.7469
H 0.2660 6.7564
6.8 mm 0.2677 6.8000
6.9 mm 0.2717 6.9000
I 0.2720 6.9088
7 mm 0.2756 7.0000
J 0.2770 7.0358
7.1 mm 0.2795 7.1000
K 0.2810 7.1374
9/32 in 0.2813 7.1438
7.2 mm 0.2835 7.2000
7.3 mm 0.2874 7.3000
L 0.2900 7.3660
7.4 mm 0.2913 7.4000
M 0.2950 7.4930
7.5 mm 0.2953 7.5000
19/64 in 0.2969 7.5406
7.6 mm 0.2992 7.6000
N 0.3020 7.6708
7.7 mm 0.3032 7.7000
7.8 mm 0.3071 7.8000
7.9 mm 0.3110 7.9000
5/16 in 0.3125 7.9375
8 mm 0.3150 8.0000
O 0.3160 8.0264
8.1 mm 0.3189 8.1000
8.2 mm 0.3228 8.2000
P 0.3230 8.2042
8.3 mm 0.3268 8.3000
21/64 in 0.3281 8.3344
8.4 mm 0.3307 8.4000
Q 0.3320 8.4328
8.5 mm 0.3347 8.5000
8.6 mm 0.3386 8.6000
R 0.3390 8.6106
8.7 mm 0.3425 8.7000
11/32 in 0.3438 8.7313
8.8 mm 0.3465 8.8000
S 0.3480 8.8392
8.9 mm 0.3504 8.9000
9 mm 0.3543 9.0000
T 0.3580 9.0932
9.1 mm 0.3583 9.1000
23/64 in 0.3594 9.1281
9.2 mm 0.3622 9.2000
9.3 mm 0.3661 9.3000
U 0.3680 9.3472
9.4 mm 0.3701 9.4000
9.5 mm 0.3740 9.5000
3/8 in 0.3750 9.5250
V 0.3770 9.5758
9.6 mm 0.3780 9.6000
9.7 mm 0.3819 9.7000
9.8 mm 0.3858 9.8000
W 0.3860 9.8044
9.9 mm 0.3898 9.9000
25/64 in 0.3906 9.9219
10 mm 0.3937 10.0000
X 0.3970 10.0838
Y 0.4040 10.2616
13/32 in 0.4063 10.3188
Z 0.4130 10.4902
10.5 mm 0.4134 10.5000
27/64 in 0.4219 10.7156
11 mm 0.4331 11.0000
7/16 in 0.4375 11.1125
11.5 mm 0.4528 11.5000
29/64 in 0.4531 11.5094
15/32 in 0.4688 11.9063
12 mm 0.4724 12.0000
31/64 in 0.4844 12.3031
12.5 mm 0.4921 12.5000
1/2 in 0.5000 12.7000
13 mm 0.5118 13.0000
33/64 in 0.5156 13.0969
17/32 in 0.5313 13.4938
13.5 mm 0.5315 13.5000
35/64 in 0.5469 13.8906
14 mm 0.5512 14.0000
9/16 in 0.5625 14.2875
14.5 mm 0.5709 14.5000
37/64 in 0.5781 14.6844
15 mm 0.5906 15.0000
19/32 in 0.5938 15.0813
39/64 in 0.6094 15.4781
15.5 mm 0.6102 15.5000
5/8 in 0.6250 15.8750
16 mm 0.6299 16.0000
41/64 in 0.6406 16.2719
16.5 mm 0.6496 16.5000
17 mm 0.6693 17.0000
43/64 in 0.6719 17.0656
11/16 in 0.6875 17.4625
17.5 mm 0.6890 17.5000
45/64 in 0.7031 17.8594
18 mm 0.7087 18.0000
23/32 in 0.7188 18.2563
18.5 mm 0.7284 18.5000
47/64 in 0.7344 18.6531
19 mm 0.7480 19.0000
3/4 in 0.7500 19.0500
49/64 in 0.7656 19.4469
19.5 mm 0.7677 19.5000
25/32 in 0.7813 19.8438
20 mm 0.7874 20.0000
51/64 in 0.7969 20.2406
20.5 mm 0.8071 20.5000
13/16 in 0.8125 20.6375
21 mm 0.8268 21.0000
53/64 in 0.8281 21.0344
27/32 in 0.8438 21.4313
21.5 mm 0.8465 21.5000
55/64 in 0.8594 21.8281
22 mm 0.8661 22.0000
7/8 in 0.8750 22.2250
22.5 mm 0.8858 22.5000
57/64 in 0.8906 22.6219
23 mm 0.9055 23.0000
29/32 in 0.9063 23.0188
21/23 in 0.9130 23.1913
59/64 in 0.9219 23.4156
23.5 mm 0.9252 23.5000
15/16 in 0.9375 23.8125
24 mm 0.9449 24.0000
61/64 in 0.9531 24.2094
24.5 mm 0.9646 24.5000
31/32 in 0.9688 24.6063
25 mm 0.9843 25.0000
63/64 in 0.9844 25.0031
1 in 1.0000 25.4000
25.5 mm 1.0039 25.5000
1 1/64 in 1.0156 25.7969
26 mm 1.0236 26.0000
1 1/32 in 1.0313 26.1938
26.5 mm 1.0433 26.5000
1 3/64 in 1.0469 26.5906
1 1/16 in 1.0625 26.9875
27 mm 1.0630 27.0000
1 5/64 in 1.0781 27.3844
27.5 mm 1.0827 27.5000
1 3/32 in 1.0938 27.7813
28 mm 1.1024 28.0000
1 7/64 in 1.1094 28.1781
28.5 mm 1.1221 28.5000
1 1/8 in 1.1250 28.5750
1 9/64 in 1.1406 28.9719
29 mm 1.1417 29.0000
1 5/32 in 1.1563 29.3688
29.5 mm 1.1614 29.5000
1 11/64 in 1.1719 29.7656
30 mm 1.1811 30.0000
1 3/16 in 1.1875 30.1625
30.5 mm 1.2008 30.5000
1 13/64 in 1.2031 30.5594
1 7/32 in 1.2188 30.9563
31 mm 1.2205 31.0000
1 15/64 in 1.2344 31.3531
31.5 mm 1.2402 31.5000
1 1/4 in 1.2500 31.7500
32 mm 1.2598 32.0000
1 17/64 in 1.2656 32.1469
32.5 mm 1.2795 32.5000
1 9/32 in 1.2813 32.5438
1 19/64 in 1.2969 32.9406
33 mm 1.2992 33.0000
1 5/16 in 1.3125 33.3375
33.5 mm 1.3189 33.5000
1 21/64 in 1.3281 33.7344
34 mm 1.3386 34.0000
1 11/32 in 1.3438 34.1313
34.5 mm 1.3583 34.5000
1 23/64 in 1.3594 34.5281
1 3/8 in 1.3750 34.9250
35 mm 1.3780 35.0000
1 25/64 in 1.3906 35.3219
35.5 mm 1.3976 35.5000
1 13/32 in 1.4063 35.7188
36 mm 1.4173 36.0000
1 27/64 in 1.4219 36.1156
36.5 mm 1.4370 36.5000
1 7/16 in 1.4375 36.5125
1 29/64 in 1.4531 36.9094
37 mm 1.4567 37.0000
1 15/32 in 1.4688 37.3063
37.5 mm 1.4764 37.5000
1 31/64 in 1.4844 37.7031
38 mm 1.4961 38.0000
1 1/2 in 1.5000 38.1000

Metric Thread – Tap Drill / Clearance Drill


Metric Tap Drill Chart
Tap size Major
Dia (mm)
Threads
per
Tap Drill
(mm)
Tap Drill
(inch)
Clearance
(mm)
Clearance
(inch)
M1.6×0.35 1.6 0.35 1.25 #55 1.8 #49
M2x0.4 2.0 0.40 1.60 #52 2.4 #41
M2.5×0.45 2.5 0.45 2.05 #46 2.9 #32
M3x.05 3.0 0.50 2.50 #39 3.4 #29
M3.5×0.6 3.5 0.60 2.90 #32 3.9 #23
M4x0.7 4.0 0.70 3.30 #30 4.5 #16
M5x0.8 5.0 0.80 4.20 #19 5.5 7/32
M6x1 6.0 1.00 5.0 #8 6.6 G
M8x1.25 8.0 1.25 6.8 H 9.0 T
M8x1 8.0 1.00 7.0 J 9.0 T
M10x1.5 10.0 1.50 8.5> R 12.0 31/64
M10x1.25 10.0 1.25 8.8 11/32 12.0 31/64
M12x1.75 12.0 1.75 10.2 13/32 14.0 35/64
M12x1.25 12.0 1.25 10.8 27/64 14.0 35/64
M14x2 14.0 2.00 12.0 15/32 16.0 5/8
M14x1.5 14.0 1.5 12.5 1/2 16.0 5/8
M16x2 16.0 2.00 14.0 35/64 18.0 45/64
M16x1.5 16.0 1.50 14.5 37/64 18.0 45/64
M18x2.5 18.0 2.50 15.5 39/64 20.0 51/64
M18x1.5 18.0 1.50 16.5 21/32 20.0 51/64
M20x2.5 20.0 2.50 17.5 11/16 22.0 7/8
M20x1.5 20.0 1.50 18.5 47/64 22.0 7/8
M22x2.5 22.0 2.50 19.5 49/64 25.0 1
M22x1.5 22.0 1.50 20.5 13/16 25.0 1
M24x3 24.0 3.00 21.0 53/64 27.0 1-5/64
M24x2 24.0 2.00 22.0 7/8 27.0 1-5/64
M27x3 27.0 3.00 24.0 15/16 30.0 1-3/16
M27x2 27.0 2.0 25.0 1 30.0 1-3/16

 
Standard UNC Tap Drill Sizes
Standard UNF Tap Drill Sizes
Standard NPT Tap Drill Sizes

Tap Drill Size – UNF


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
5/16-24 I
3/8-24 Q
7/16-20 W
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

 
Metric Tap Drill Sizes
Standard UNC Tap Drill Sizes
Standard NPT Tap Drill Sizes

Tap Drill Size – UNC


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
5/16-18 F
3/8-16 5/16
7/16-14 U
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

 
Metric Tap Drill Sizes
Standard UNF Tap Drill Sizes
Standard NPT Tap Drill Sizes