Tap Drill Reference

Imperial Tap Drill Chart
Machine Screw Size Number of Threads Per Inch Minor Dia. Tap Drills Clearance Hole Drills

Aluminum, Brass, Hardwoods & Plastics

75% Thread

Stainless Steel, Steels & Iron

50% Thread

 All Materials
Close Fit Free Fit
No. or Dia. Major Dia. Drill Size Decimal Equiv. Drill Size Decimal Equiv. Drill Size Decimal Equiv. Drill Size Decimal Equiv.
0 .0600 80 .0447 3/64 .0469 55 .0520 52 .0635 50 .0700
1 .0730 64 .0538 53 .0595 1/16 .0625 48 .0760 46 .0810
72 .0560 53 .0595 52 .0635
2 .0860 56 .0641 50 .0700 49 .0730 43 .0890 41 .0960
64 .0668 50 .0700 48 .0760
3 .0990 48 .0734 47 .0785 44 .0860 37 .1040 35 .1100
56 .0771 45 .0820 43 .0890
4 .1120 40 .0813 43 .0890 41 .0960 32 .1160 30 .1285
48 .0864 42 .0935 40 .0980
5 .1250 40 .0943 38 .1015 7/64 .1094 30 .1285 29 .1360
44 .0971 37 .1040 35 .1100
6 .1380 32 .0997 36 .1065 32 .1160 27 .1440 25 .1495
40 .1073 33 .1130 31 .1200
8 .1640 32 .1257 29 .1360 27 .1440 18 .1695 16 .1770
36 .1299 29 .1360 26 .1470
10 .1900 24 .1389 25 .1495 20 .1610 9 .1960 7 .2010
32 .1517 21 .1590 18 .1695
12 .2160 24 .1649 16 .1770 12 .1890 2 .2210 1 .2280
28 .1722 14 .1820 10 .1935
32 .1777 13 .1850 9 .1960
1/4 .2500 20 .1887 7 .2010 7/32 .2188 F .2570 H .2660
28 .2062 3 .2130 1 .2280
32 .2117 7/32 .2188 1 .2280
5/16 .3125 18 .2443 F .2570 J .2770 P .3230 Q .3320
24 .2614 I .2720 9/32 .2812
32 .2742 9/32 .2812 L .2900
3/8 .3750 16 .2983 5/16 .3125 Q .3320 W .3860 X .3970
24 .3239 Q .3320 S .3480
32 .3367 11/32 .3438 T .3580

7/16

.4375

 14 .3499 U .3680 25/64 .3906

29/64

.4531

15/32

.4687
20 .3762 25/64 .3906 13/32 .4062
28 .3937 Y .4040 Z .4130
1/2 .5000 13 .4056 27/64 .4219 29/64 .4531 33/64 .5156 17/32 .5312
20 .4387 29/64 .4531 15/32 .4688
28 .4562 15/32 .4688 15/32 .4688
9/16 .5625 12 .4603 31/64 .4844 33/64 .5156 37/64 .5781 19/32 .5938
18 .4943 33/64 .5156 17/32 .5312
24 .5114 33/64 .5156 17/32 .5312
5/8 .6250 11 .5135 17/32 .5312 9/16 .5625 41/64 .6406 21/32 .6562
18 .5568 37/64 .5781 19/32 .5938
24 .5739 37/64 .5781 19/32 .5938
1-1/16 .6875 24 .6364 41/64 .6406 21/32 .6562 45/64 .7031 23/32 .6562

3/4

.7500

 10 .6273 21/32 .6562 11/16 .6875

49/64

.7656

25/32

.7812
16 .6733 11/16 .6875 45/64 .7031
20 .6887 45/64 .7031 23/32 .7188
1-3/16 .8125 20 .7512 49/64 .7656 25/32 .7812 53/64 .8281 27/32 .8438
7/8 .8750 9 .7387 49/64 .7656 51/64 .7969 57/64 .8906 29/32 .9062
14 .7874 13/16 .8125 53/64 .8281
20 .8137 53/64 .8281 27/32 .8438
15/16 .9375 20 .8762 57/64 .8906 29/32 .9062 61/64 .9531 31/32 .9688
1 1.000 8 .8466 7/8 .8750 59/64 .9219 1-1/64 1.0156 1-1/32 1.0313
12 .8978 15/16 .9375 61/64 .9531
20 .9387 61/64 .9531 31/32 .9688
1-1/16 1.0625 18 .9943 1.000 1.000 1-1/64 1.0156 1-5/64 1.0781 1-3/32 1.0938
1-1/8 1.1250 7 .9497 63/64 .9844 1-1/32 1.0313 1-9/64 1.1406 1-5/32 1.1562
12 1.0228 1-3/64 1.0469 1-5/64 1.0781
18 1.0568 1-1/16 1.0625 1-5/64 1.0781
1-3/16 1.1875 18 1.1193 1-1/8 1.1250 1-9/64 1.1406 1-13/64 1.2031 1-7/32 1.2188

1-1/4

1.2500

 7 1.0747 1-7/64 1.1094 1-5/32 1.1562

1-17/64

1.2656

1-9/32

1.2812
12 1.1478 1-11/64 1.1719 1-13/64 1.2031
18 1.1818 1-3/16 1.1875 1-13/64 1.2031
1-5/16 1.3125 18 1.2443 1-1/4 1.2500 1-17/64 1.2656 1-21/64 1.3281 1-11/32 1.3438
1-3/8 1.3750 6 1.1705 1-7/32 1.2187 1-17/64 1.2656 1-25/64 1.3906 1-13/32 1.4062
12 1.2728 1-19/64 1.2969 1-21/64 1.3281
18 1.3068 1-5/16 1.3125 1-21/64 1.3281
1-7/16 1.4375 18 1.3693 1-3/8 1.3750 1-25/64 1.3906 1-29/64 1.4531 1-15/32 1.4688
1-1/2 1.500 6 1.2955 1-11/32 1.3437 1-25/64 1.3906 1-33/64 1.5156 1-17/32 1.5312
12 1.3978 1-27/64 1.4219 1-7/16 1.4375
18 1.4318 1-7/16 1.4375 1-29/64 1.4531
1-9/16 1.5625 18 1.4943 1-12 1.500 1-33/64 1.5156 1-37/64 1.5781 1-19/32 1.5938
1-5/8 1.625 18 1.5568 1-9/16 1.5625 1-37/64 1.5781 1-41/64 1.6406 1-21/32 1.6562
1-11/16 1.6875 18 1.6193 1-5/8 1.6250 1-41/64 1.6406 1-45/64 1.7031 1-23/32 1.7188
1-3/4 1.750 5 1.5046 1-9/16 1.5625 1-5/8 1.6250 1-49/64 1.7659 1-25/32 1.7812

Metric Tap Drill Chart
Tap size Major
Dia (mm)		 Threads
per 		Tap Drill
(mm)		 Tap Drill
(inch)		 Clearance
(mm)		 Clearance
(inch)
M1.6x0.35 1.6 0.35 1.25 #55 1.8 #49
M2x0.4 2.0 0.40 1.60 #52 2.4 #41
M2.5x0.45 2.5 0.45 2.05 #46 2.9 #32
M3x.05 3.0 0.50 2.50 #39 3.4 #29
M3.5x0.6 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

Pipe Threads
- American Standard British Standard
Nominal
OD		 Threads
per inch		 NPT NPS Threads
per inch		 Drill size
1/16 27 D 1/4 28 G
1/8 27 R S 28 11/32
1/4 18 7/16 29/64 19 15/32
3/8 18 37/64 19/32 19 39/64
1/2 14 23/32 47/64 14 3/4
5/8 - - - 14 53/64
3/4 14 59/64 15/16 14 31/32
7/8 - - - 14 1-7/64
1 11.5 1-5/32 1-3/16 11 1-7/32

Drill Chart - Standard Drill Sizes / Millimeter Sizes

(See typical tolerances of drilled holes at bottom of page)

Drill
(in.)		 Decimal Drill
(in.)		 Decimal Drill
(in.)		 Decimal Drill
(mm)		 Decimal
(in.)		 Drill
(mm)		 Decimal
(in.)		 Drill
(mm)		 Decimal
(in.)
80 .0135 1/8 .1250 O .3160 .35 .0138 3.4 .1339 8.0 .3150
79 .0145 30 .1285 P .3230 .4 .0157 3.5 .1378 8.1 .3189
1/64 .0156 29 .1360 21/64 .3281 .45 .0177 3.6 .1417 8.2 .3228
78 .0160 28 .1405 Q .3320 .5 .0197 3.7 .1457 8.25 .3248
77 .0180 9/64 .1406 R .3390 .55 .0217 3.75 .1477 8.3 .3267
76 .0200 27 .1440 11/32 .3437 .6 .0236 3.8 .1496 8.4 .3307
75 .0210 26 .1470 S .3480 .65 .0256 3.9 .1535 8.5 .3346
74 .0225 25 .1495 T .3580 .7 .0276 4.0 .1575 8.6 .3386
73 .0240 24 .1520 23/64 .3594 .75 .0295 4.1 .1614 8.7 .3425
72 .0250 23 .1540 U .3680 .8 .0315 4.2 .1654 8.75 .3445
71 .0260 5/32 .1562 3/8 .3750 .85 .0335 4.25 .1674 8.8 .3465
70 .0280 22 .1570 V .3770 .9 .0355 4.3 .1693 8.9 .3504
69 .0292 21 .1590 W .3860 .95 .0374 4.4 .1732 9.0 .3543
68 .0310 20 .1610 25/64 .3906 1.0 .0394 4.5 .1771 9.1 .3583
1/32 .0313 19 .1660 X .3970 1.05 .0413 4.6 .1811 9.2 .3622
67 .0320 18 .1695 Y .4040 1.1 .0433 4.7 .1850 9.25 .3642
66 .0330 11/64 .1719 13/32 .4062 1.15 .0453 4.75 .1870 9.35 .3661
65 .0350 17 .1730 Z .4130 1.2 .0472 4.8 .1890 9.4 .3701
64 .0360 16 .1770 27/64 .4219 1.25 .0492 4.9 .1929 9.5 .3740
63 .0370 15 .1800 7/16 .4375 1.3 .0512 5.0 .1968 9.6 .3780
62 .0380 14 .1820 29/64 .4531 1.35 .0531 5.1 .2008 9.7 .3819
61 .0390 13 .1850 15/32 .4687 1.4 .0551 5.2 .2047 9.75 .3839
60 .0400 3/16 .1875 31/64 .4844 1.45 .0571 5.25 .2067 9.8 .3858
59 .0410 12 .1890 ½ .5000 1.5 .0591 5.3 .2087 9.9 .3898
58 .0420 11 .1910 33/64 .5156 1.55 .0610 5.4 .2126 10.0 .3937
57 .0430 10 .1935 17/32 .5312 1.6 .0629 5.5 .2165 10.5 .4133
56 .0465 9 .1960 35/64 .5469 1.65 .0650 5.6 .2205 11.0 .4331
3/64 .0469 8 .1990 9/16 .5625 1.7 .0669 5.7 .2244 11.5 .4528
55 .0520 7 .2010 37/64 .5781 1.75 .0689 5.75 .2264 12.0 .4724
54 .0550 13/64 .2031 19/32 .5937 1.8 .0709 5.8 .2283 12.5 .4921
53 .0595 6 .2040 39/64 .6094 1.85 .0728 5.9 .2323 13.0 .5118
1/16 .0625 5 .2055 5/8 .6250 1.9 .0748 6.0 .2362 13.5 .5315
52 .0635 4 .2090 41/64 .6406 1.95 .0768 6.1 .2401 14.0 .5512
51 .0670 3 .2130 21/32 .6562 2.0 .0787 6.2 .2441 14.5 .5708
50 .0700 7/32 .2187 43/64 .6719 2.05 .0807 6.25 .2461 15.0 .5906
49 .0730 2 .2210 11/16 .6875 2.1 .0827 6.3 .2480 15.5 .6102
48 .0760 1 .2280 45/64 .7031 2.15 .0846 6.4 .2520 16.0 .6300
5/64 .0781 A .2340 23/32 .7187 2.2 .0866 6.5 .2559 16.5 .6496
47 .0785 15/64 .2344 47/64 .7344 2.25 .0886 6.6 .2598 17.0 .6693
46 .0810 B .2380 ¾ .7500 2.3 .0905 6.7 .2638 17.5 .6889
45 .0820 C .2420 49/64 .7656 2.35 .0925 6.75 .2658 18.0 .7087
44 .0860 D .2460 25/32 .7812 2.4 .0945 6.8 .2677 18.5 .7283
43 .0890 E .2500 51/64 .7969 2.45 .0965 6.9 .2716 19.0 .7480
42 .0935 ¼ .2500 13/16 .8125 2.5 .0984 7.0 .2756 19.5 .7677
3/32 .0937 F .2570 53/64 .8281 2.55 .1004 7.1 .2795 20.0 .7874
41 .0960 G .2610 27/32 .8437 2.6 .1024 7.2 .2835 20.5 .8071
40 .0980 17/64 .2656 55/64 .8594 2.65 .1043 7.25 .2855 21.0 .8268
39 .0995 H .2660 7/8 .8750 2.7 .1063 7.3 .2874 21.5 .8465
38 .1015 I .2720 57/64 .8906 2.75 .1083 7.4 .2913 22.0 .8661
37 .1040 J .2770 29/32 .9062 2.8 .1102 7.5 .2953 22.5 .8858
36 .1065 K .2811 59/64 .9219 2.9 .1142 7.6 .2990 23.0 .9055
7/64 .1093 9/32 .2812 15/16 .9375 3.0 .1181 7.7 .3031 23.5 .9252
35 .1100 L .2900 61/64 .9531 3.1 .1220 7.75 .3051 24.0 .9449
34 .1110 M .2950 31/32 .9687 3.2 .1260 7.8 .3071 24.5 .9646
33 .1130 19/64 .2968 63/64 .9844 3.25 .1280 7.9 .3110 25.0 .9843
32 .1160 N .3020 1 1.000 3.3 .1299        
31 .1200 5/16 .3125                

HOLE DIA TOLERANCE-STANDARD DRILLED HOLE TOLERANCES                   .0135 THRU .125   +.004/ -.001
FOR HOLES DRILLED WITH A DRILLING                                                               .1260 THRU .25     +.005/ -.001
MACHINE USING SUITABLE JIGS AND .                                                               .2510 THRU .500    +.006/-.001                 
FIXTURES, THE HOLE TOLERANCES DE-                                                              .5010 THRU .750     +.008/ -.001
PEND UPON THE DIAMETER OF THE HOLE                                                           .7510 THRU 1.000  +.010/ -.001
AND INCREASE AS THE HOLE DIAMETER                                                            1 .001  THRU 2.000  +.012/ -.001   
INCREASES. THE FOLLOWING ARE STANDARD            
TOLERANCES FOR GENERAL MACHINE                                                                    
WORK AND APPLY IN ALL CASES EXCEPT
WHERE GREATER OR LESSER ACCURACY IS                                                         
REQUIRED BY THE DESIGN.
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