Basic major dia (mertric)	Gauge Number or Fraction Size	Gauge Number Tap size	NF/NC UNF/UNC	Threads per inch	Basic major dia (inches)	Basic effective dia (inches)	Basic effective dia (metric)	Basic minor dia of ext. threads (inches)	Basic minor dia of int. threads (inches)	Tapping Drill size	Typical uses and general comments
1.52	# 0	0-80	UNF	80	.0600	.0519	1.32	.0447	.0465	3/64
1.85	# 1	1-64	UNC	64	.0730	.0629	1.60	.0538	.0561	#54
2.18	# 2	2-56	UNC	56	.0860	.0744	1.89	.0641	.0667	#50
2.18	# 2	2-64	UNF	64	.0860	.0759	1.93	.0668	.0691	#50
2.84	# 4	4-40	UNC	40	.1120	.0958	2.43	.0813	.0849	#43
2.84	# 4	4-48	UNF	48	.1120	.0985	2.50	.0864	.0894	#42
3.18	# 5	5-40	UNC	40	.1250	.1088	2.76	.0943	.0979	#38
3.18	# 5	5-44	UNF	44	.1250	.1102	2.80	.0971	.1004	#37
3.45	# 6	6-32	UNC	32	.1360	.1177	2.99	.0997	.1042	#36
3.45	# 6	6-40	UNF	40	.1360	.1218	3.09	.1073	.1109	#33
4.17	# 8	8-32	UNC	32	.1640	.1437	3.65	.1257	.1302	#29
4.17	# 8	8-36	UNF	36	.1640	.1460	3.71	.1299	.1339	#29
4.83	# 10	10-24	UNC	24	.1900	.1629	4.14	.1389	.1449	#25
4.83	# 10	10-32	UNF	32	.1900	.1697	4.31	.1517	.1562	#21
5.49	# 12	12-32	UNEF	32	0.2160					4.8mm
6.35	1/4"	1/4-20	UNC	20	.2500	.2175	5.52	.1887	.1959	#7
6.35	1/4"	1/4-28	UNF	28	.2500	.2268	5.76	.2062	.2113	#3
6.35	1/4"	1/4-32	UNEF	32	0.2500					5.7mm	SMA Bulkhead
7.94	5/16"	5/16-18	UNC	18	.3125	.2764	7.02	.2443	.2524	F
7.94	5/16"	5/16-24	UNF	24	.3125	.2854	7.25	.2614	.2674	I
7.94	5/16"	5/6-32	UNEF	32	.3125
9.53	3/8"	3/8-16	UNC	16	.3750	.3344	8.49	.2983	.3073	5/16
9.53	3/8"	3/8-24	UNF	24	.3750	.3479	8.84	.3239	.3299	Q
9.53	3/8"	3/8-32	UNEF	32	.3750					8.85mm	BNC recepticals
11.11	7/16"	7/16-14	UNC	14	.4375	.3911	9.93	.3499	.3602	U
11.11	7/17"	7/16-20	UNF	20	.4375	.4050	10.29	.3762	.3834	25/64
12.70	1/2"	1/2-13	UNC	13	.5000	.4500	11.43	.4056	.4167	27/64
12.70	1/2"	1/2-20	UNF	20	.5000	.4675	11.87	.4387	.4459	29/64
12.70	1/2"	1/2-28	UNEF	28	.5000					10.8mm	BNC Bulkhead
14.29	9/16"	9/16-12	UNC	12	.5625	.5084	12.91	.4603	.4723	31/64
14.29	9/16"	9/16-18	UNF	18	.5625	.5264	13.37	.4943	.5024	33/64
15.88	5/8"	5/8-11	UNC	11	.6250	.5660	14.38	.5135	.5266	17/32
15.88	5/8"	5/8-18	UNF	18	.6250	.5869	14.91	.5568	.5649	37/64
15.88	5/8"	5/8-24	UNEF	24	.6250					15.0mm	"N" series Bulkhead
19.05	3/4"	3/4-10	UNC	10	.7500	.6650	16.89	.6273	.6417	21/32
19.05	3/4"	3/4-16	UNF	16	.7500	.7094	18.02	.6733	.6823	11/16
22.23	7/8"	7/8-9	UNC	9	.8750	.8028	20.39	.7387	.7547	49/64
22.23	7/8"	7/8-14	UNF	14	.8750	.8286	21.05	.7874	.7977	13/16
25.40	1"	1-8	UNC	8	1.000	.9188	23.34	.8466	.8647	7/8
25.40	1"	1-14	UNF	14	1.000	.9459	24.03	.8978	.9098	15/16
Sizes above 1" are rarely used in electronics - see other resources as required
Note: Yellow highlights identify items of special use in electronics.