Tap and Drill Chart 1artworkz

Recommended tap drill to use for 75% depth of thread
What You Need to Know about Taps and Dies

To Tap This Size Screw Or Bolt	Use This Drill Bit	Closest Fractional	Decimal Inches
0-80 NF	3/64"	3/64"	0.0469
1-64 NC	#53	-	0.0595
1-72 NF	#53	1/16"	0.0595
2-56 NC	#50	-	0.0700
2-64 NF	#50	-	0.0700
3-48 NC	#47	5/64"	0.0785
3-56 NF	#45	-	0.0820
4-36 NS	#44	-	0.0860
4-40 NC	#43	3/32"	0.0890
4-48 NF	#42	3/32"	0.0935
3mm-.060mm	2.5mm	-	0.0984
1/8-40 NS	#38	-	0.1015
5-40 NC	#38	-	0.1015
5-44 NF	#37	-	0.1040
6-32 NC	#35	7/64"	0.1100
6-36 NS	#34	-	0.1110
6-40 NF	#33	-	0.1130
6-48 NS	#31	-	0.1200
4mm-0.70mm	3.4mm	-	0.1338
4mm-.075mm	3.4mm	-	0.1338
8-32 NC	#29	-	0.1360
8-36 NF	#29	9/64"	0.1360
8-40 NS	#28	-	0.1405
3/16-24 NS	#26	-	0.1470
10-24 NC	#25	5/32"	0.1495
3/16-32 NS	#22	-	0.1570
10-32 NF	#21	5/32"	0.1590
5mm-.090mm	4.2mm	-	0.1653
5mm-.080mm	4.3mm	-	0.1693
12-24 NC	#16	11/64"	0.1770
12-28 NF	#14	3/16"	0.1820
12-32 NEF	#13	-	0.1850
14-20 NS	#10	-	0.1935
1/4-20 NC	#7	13/64"	0.2010
14-24 NS	#7	-	0.2010
6mm-1.00mm	5.2mm	-	0.2047
1/4-24 NS	#4	-	0.2090
1/4-28 NF	#3	7/32"	0.2130
1/4-32 NEF	7/32"	7/32"	0.2188
1/4-40 NS	#1	-	0.2280
7mm-1.00mm	6.1mm	15/64"	0.2401
5/16-18 NC	Ltr.F	17/64"	0.2570
8mm-1.25mm	6.9mm	17/64"	0.2716
5/16-24 NF	Ltr.I	-	0.2720
8mm-1.00mm	7.1mm	-	0.2795
5/16-32 NEF	9/32"	9/32"	0.2812
9mm-1.25mm	7.9mm	-	0.3110
3/8-16 NC	5/16"	5/16"	0.3125
9mm-1.00mm	8.1mm	-	0.3189
9mm-0.75mm	8.3mm	-	0.3268
3/8-24 NF	Ltr.Q	21/64"	0.3320
1/8-27 NPT	Ltr.R	-	0.3390
10mm-1.50mm	8.7mm	-	0.3425
10mm-1.25mm	8.9mm	11/32"	0.3503
10mm-1.00mm¹	9.1mm	-	0.3583
7/16-14 NC	Ltr.U	23/64"	0.3680
11mm-1.50mm	9.7mm	-	0.3818
7/16-20 NF²	25/64"	25/64"	0.3906
12mm-1.75mm	10.5mm	-	0.4133
12mm-1.50mm	10.7mm	27/64"	0.4212
1/2-13 NC	27/64"	27/64"	0.4219
12mm-1.25mm¹	10.9mm	27/64"	0.4291
1/4-18 NPT²	7/16"	7/16"	0.4375
1/2-20 NF	29/64"	29/64"	0.4531
1/2-24 NS	29/64"	29/64"	0.4531
14mm-2.00mm	12.2mm	-	0.4803
9/16-12 NC	31/64"	31/64"	0.4844
14mm-1.50mm	12.7mm	-	0.4999
14mm-1.25mm¹	12.8mm	-	0.5039
9/16-18 NF	33/64"	33/64"	0.5156
5/8-11 NC	17/32"	17/32"	0.5312
16mm-2.00mm	14.2mm	35/64"	0.5590
5/8-18 NF	37/64"	37/64"	0.5781
3/8-18 NPT²	37/64"	37/64"	0.5781
16mm-1.50mm	14.7mm	-	0.5787
11/16-11 NS	19/32"	19/32"	0.5938
18mm-2.50mm	15.8mm	39/64"	0.5220
11/16-16 NS	5/8"	5/8"	0.6250
3/4-10 NC	21/32"	21/32"	0.6562
18mm-1.50mm¹	16.8mm	-	0.6614
3/4-16 NF	11/16"	11/16"	0.6875
20mm-2.50mm	17.8mm	11/16"	0.7008
1/2-14 NPT²	45/64"	45/64"	0.7031
7/8-9 NC	49/64"	49/64"	0.7656
7/8-14 NF	13/16"	13/16"	0.8125
22mm-1.50mm	20.9mm	-	0.8228
7/8-18 NS¹	53/64"	53/64"	0.8281
24mm-3.00mm	21.4mm	53/64"	0.8425
1.8 NC	7/8"	7/8"	0.8750
24mm-2.00mm	22.3mm	-	0.8779
1.12 NF	59/64"	59/64"	0.9219
3/4-14 NPT²	59/64"	59/64"	0.9219
1-14 NS	15/16"	15/16"	0.9375
1 1/8-7 NC	63/64"	63/64"	0.9844
1 1/8-12 NF	1 3/64"	1 3/64"	1.0469
1 1/4-7 NC	1 7/64"	1 7/64"	1.1094
1-11 1/2 NPT²	1 5/32"	1 5/32"	1.1562
1 1/4-12 NF	1 11/64"	1 11/64"	1.1719
1 3/8-6 NC	1 7/32"	1 7/32"	1.2188
1 3/8-12 NF	1 19/64"	1 19/64"	1.2969
1 1/2-6 NC	1 11/32"	1 11/32"	1.3438
1 1/2"-12 NF	1 27/64"	1 27/64"	1.4219
1 1/4-11 1/2 NPT	1 1/2"	1 1/2"	1.5000
1 1/2-11 1/2 NPT	1 47/64"	1 47/64"	1.7344
2-11 1/2 NPT	2 7/32"	2 7/32"	2.2188

¹ = These Sizes are Spark Plug Taps
² = These Sizes are National Pipe Tapered Taps
NC = National Course, NF = National Fine
NPT = National Pipe Taper, NEF = Narional Extra Fine,
NS = National Special, mm = milimeter
* See notes below.

NS changed to UNS
NC changed to UNC
NF changed to UNF
NEF changed to UNEF
NS changed to UNS

The American National Standard became obsoleted in 1949 and replaced with the Unified National Standard for two reasons. The first reason was to provide interchangeability with Canada and United Kingdom thread standards. The second reason was to correct certain thread production difficulties.

In all cases the threads made to the Unified National Standard are designed to screw together with the obsoleted American National Standard.