Standard Tap & Drill Chart for 75% Thread Depth
To the best of my knowledge the following information is accurate

Tap Size Drill Size Clearance Size
Aluminum, Brass & Plastic Steel, Stainless & Iron
Drill
Size		 Fractional
Drill Size		 Decimal
Size		 Drill
Size		 Fractional
Drill Size		 Decimal
Size		 Drill
Size		 Decimal
Size
0-80 NF 3/64" 3/64" .0469 3/64" 3/64" .0469 #51 .0700"
1-64 #53 1/16" .0595 #53 1/16" .0595 #46 .0810"
1-72 #53 1/16" .0595 #53 1/16" .0595 #46 .0810"
2-56 #50 5/64" .070 #51 5/64" .0670 #41 .0960"
2-64 #50 5/64" .070 #50 5/64" .0700 #41 .0960"
3-48 #47 5/64" .0785 #47 5/64" .0785 #35 .1100"
3-56 #45 5/64" .0820 #46 5/64" .0810 #35 .1100"
4-40 #43 3/32" .0890 #44 3/32" .0860 #30 .1285"
4-48 #42 3/32" .0935 #42 3/32" .0935 #30 .1285"
5-40 #38 7/64" .1015 #40 3/32" .0980 #29 .1360"
5-44 #37 7/64" .1040 #38 3/32" .1015 #29 .1360"
6-32 #36 7/64" .1065 #36 7/64" .1065 #25 .1495"
6-40 #33 7/64" .1130 #34 7/64" .1100 #25 .1495"
8-32 #29 9/64" .1360 #29 9/64" .1360 #16 .1770"
8-36 #29 9/64" .1360 #29 9/64" .1360 #16 .1770"
10-24 #25 5/32" .1495 #26 5/32" .1470 #7 .2010"
10-32 #21 5/32" .1590 #22 5/32" .1570 #7 .2010"
12-24 #16 11/64" .1770 #17 11/64" .1730 #1 .2280"
12-28 #14 3/16" .1820 #15 3/16" .1800 #1 .2280"
12-32 #13 3/16" .1850 #13 3/16" .1850 #1 .2280"
1/4"-20 #7 13/64" .2010 #7 13/64" .2010 H .2660"
1/4"-28 #3 13/64" .2130 #3 13/64" .2130 H .2660"
1/4"-32 7/32" 7/32" .2188 7/32" 7/32" .2188 H .2660"
5/16"-18 F 17/64" .2570 F 17/64" .2570 Q .3320"
5/16"-24 I 17/64" .2720 H 17/64" .2660 Q .3320"
5/16"-32 9/32" 9/32" .2812 9/32" 9/32" .2812 Q .3320"
3/8"-16 5/16" 5/16" .3125 5/16" 5/16" .3125 X .3970"
3/8"-24 Q 21/64" .3320 Q 21/64" .3320 X .3970"
3/8"-32 11/32" 11/32" .3438 11/32" 11/32" .3438 X .3970"
7/16"-14 U 23/64" .3680 U 23/64" .3680 15/32" .4687"
7/16"-20 25/64" 25/64" .3906 25/64" 25/64" .3906 15/32" .4687"
7/16"-28 Y 13/32" .4040 Y 13/32" .4040 15/32" .4687"
1/2"-13 27/64" 27/64" .4219 27/64" 27/64" .4219 17/32" .5312"
1/2"-20 29/64" 29/64" .4531 29/64" 29/64" .4531 17/32" .5312"
1/2"-28 15/32" 15/32" .4688 15/32" 15/32" .4688 17/32" .5312"
9/16"-12 31/64" 31/64" .4844 31/64" 31/64" .4844 19/32" .5938"
9/16"-18 33/64" 33/64" .5156 1/2" 1/2" .5000 19/32" .5938"
9/16"-24 33/64" 33/64" .5156 1/2" 1/2" .5000 19/32" .5938"
5/8"-11 17/32" 17/32" .5313 17/32" 17/32" .5313 21/32" .6572"
5/8"-18 37/64" 37/64" .5781 9/16" 9/16" .5625 21/32" .6572"
5/8"-24 37/64" 37/64" .5781 9/16" 9/16" .5625 21/32" .6572"
11/16"-24 41/64" 41/64" .6410 41/64" 41/64" .6410 23/32" .7192"
3/4"-10 21/32" 21/32" .6562 21/32" 21/32" .6562 25/32" .7812"
3/4"-16 11/16" 11/16" .6875 11/16" 11/16" .6875 25/32" .7812"
3/4"-20 45/64" 45/64" .7031 45/64" 45/64" .7031 25/32" .7812"
13/16"-20 49/64" 49/64" .7656 49/64" 49/64" .7656 27/32" .8438"
7/8"-9 49/64" 49/64" .7656 49/64" 49/64" .7656 29/32" .9062"
7/8"-14 13/16" 13/16" .8125 51/64" 51/64" .7969 29/32" .9062"
7/8"-20 53/64" 53/64" .8281 53/64" 53/64" .8281 29/32" .9062"
15/16"-20 57/64" 57/64" .8906 57/64" 57/64" .8906 31/32" .9688"
1"-8 7/8" 7/8" .875 7/8" 7/8" .875 1-1/32" 1.0313"
1"-12 15/16" 15/16" .9375 59/64" 59/64" .9219 1-1/32" 1.0313"
1"-20 61/64" 61/64" .9531 61/64" 61/64" .9531 1-1/32" 1.0313"
1-1/16"-18 1" 1" 1.000 1" 1" 1.000 1-3/32" 1.0938"
1-1/8"-7 63/64" 63/64" .9844 63/64" 63/64" .9844 1-5/32" 1.1562"
1-1/8"-12 1-3/64" 1-3/64" 1.046 1-3/64" 1-3/64" 1.046 1-5/32" 1.1562"
1-1/8"-18 1-1/16" 1-1/16" 1.062 1-1/16" 1-1/16" 1.062 1-5/32" 1.1562"
1-3/16"-18 1-1/8" 1-1/8" 1.125 1-1/8" 1-1/8" 1.125 1-7/32" 1.2188"
1-1/4"-7 1-7/64" 1-7/64" 1.1094 1-7/64" 1-7/64" 1.109 1-9/32" 1.2812"
1-1/4"-12 1-11/64" 1-11/64" 1.1719 1-11/64" 1-11/64" 1.172 1-9/32" 1.2812"
1-1/4"-18 1-3/16" 1-3/16" 1.1870 1-3/16" 1-3/16" 1.187 1-9/32" 1.2812"
1-5/16"-18 1-1/4" 1-1/4" 1.250 1-1/4" 1-1/4" 1.250 1-11/32" 1.3738"
1-3/8"-6 1-7/32" 1-7/32" 1.2187 1-7/32" 1-7/32" 1.219 1-13/32" 1.4062"
1-3/8"-12 1-19/64" 1-19/64" 1.2969 1-19/64" 1-19/64" 1.297 1-13/32" 1.4062"
1-3/8"-18 1-5/16" 1-5/16" 1.3125 1-5/16" 1-5/16" 1.313 1-13/32" 1.4062"
1-7/16"-18 1-3/8" 1-3/8" 1.3750 1-3/8" 1-3/8" 1.375 1-15/32" 1.4688"
1-1/2"-6 1-11/32" 1-11/32" 1.3437 1-21/64" 1-21/64" 1.328 1-17/32" 1.5312"
1-1/2"-12 1-27/64" 1-27/64" 1.4219 1-27/64" 1-27/64" 1.422 1-17/32" 1.5312"
1-1/2"-18 1-7/16" 1-7/16" 1.4375 1-7/16" 1-7/16" 1.438 1-17/32" 1.5312"
1-9/16"-18 1-1/2" 1-1/2" 1.5000 1-1/2" 1-1/2" 1.500 1-19/32" 1.5938"
1-5/8"-18 1-9/16" 1-9/16" 1.5625 1-9/16" 1-9/16" 1.563 1-21/32" 1.6562"
1-11/16"-18 1-5/8" 1-5/8" 1.6250 1-5/8" 1-5/8" 1.625 1-23/32" 1.7188"
1-3/4"-5 1-9/16" 1-9/16" 1.5625 1-9/16" 1-9/16" 1.563 1-25/32" 1.7812"


Metric Tap & Drill Chart for 75% Thread Depth
To the best of my knowledge the following information is accurate

Tap Size Drill Size Clearance Size   Tap Size Drill Size Clearance Size
MM Inch MM Inch MM Inch MM Inch
M1.6 x 0.35 1.25 # 55 1.8 # 49 M14 x 2.0 12 15/32" 16 5/8"
M2 x 0.4 1.60 # 52 2.4 # 41 M14 x 1.5 12.5 1/2" 16.0 5/8"
M2.5 x 0.45 2.05 # 46 2.9 # 32 M16 x 2.0 14 35/64" 18 45/64"
M3 x 0.5 2.50 # 39 3.4 # 29 M16 x 1.5 14.5 37/64" 18 45/64"
M3.5 x 0.6 2.90 # 32 3.9 # 23 M18 x 2.5 15.5 39/64" 20.0 51/64"
M4 x 0.7 3.30 # 30 4.5 # 16 M18 x 1.5 16.5 21/32" 20.0 51/64"
M5 x 0.8 4.2 # 19 5.5 7/32" M20 x 2.5 17.5 11/16" 22.0 7/8"
M6 x 1.0 5.0 # 8 6.6 G M20 x 1.5 18.5 47/64" 22.0 7/8"
M8 x 1.25 6.8 H 9.0 T M22 x 2.5 19.5 49/64" 25.0 1"
M8 x 1.0 7.0 J 9.0 T M22 x 1.5 20.5 13/16" 25.0 1"
M10 x 1.50 8.5 R 12.0 31/64" M24 x 3.0 21 53/64" 27.0 1-5/64"
M10 x 1.25 8.8 11/32" 12.0 31/64" M24 x 2.0 22 7/8" 27.0 1-5/64"
M12 x 1.75 10.2 13/32" 14.0 35/64" M27 x 3.0 24 15/16" 30.0 1-3/16"
M12 x 1.25 10.2 13/32" 14.0 35/64"          


Pipe Tap & Drill Chart
To the best of my knowledge the following information is accurate

Tap Size NPT Drill Size NPTF Drill Size NPS Drill Size
1/16" - 27 D D 1/4"
1/8" - 27 Q R 11/32"
1/4" - 18 7/16" 7/16" 7/16"
3/8" - 18 9/16" 37/64" 37/64"
1/2" - 14 45/64" 45/64" 23/32"
3/4" - 14 29/32" 59/64" 59/64"
1" - 11-1/2 1-9/64" 1-5/32" 1-5/32"
1-1/4" - 11-1/2 1-31/64" 1-1/2" 1-1/2"
1-1/2" - 11-1/2 1-47/64" 1-47/64" 1-3/4"
2" - 11-1/2 2-13/64" 2-7/32" 2-7/32"
2-1/2" - 8 2-5/8" 2-41/64" 2-21/32"
3" - 8 3-1/4"   3-9/32"
3-1/2" - 8 3-3/4"   3-25/32"
4" - 8 4-1/4"   4-9/32"


Helicoil Tap & Drill Chart
To the best of my knowledge the following information is accurate

Tap Size Drill Size   Tap Size Drill Size   Tap Size Drill Size
2 - 56 3/32"   8 - 32 # 17   5/16" - 24 21/64"
3 - 48 # 33   10 - 24 13/64"   3/8" - 16 X
4 - 40 # 31   10 - 32 # 7   3/8" - 24 25/64"
4 - 48 # 30   12 - 24 # 2   7/16" - 14 29/64"
5 - 40 # 30   1/4" - 20 17/64"   7/16" - 20 29/64"
6 - 32 # 25   1/4" - 28 G   1/2" - 13 33/64"
6 - 40 # 26   5/16" - 18 Q   1/2" - 20 33/64"