UNF/UNRF - Fine Thread (in)

Bolt Size	Major Diameter (in)	Threads per Inch (tpi)	Pitch Diameter (in)	Minor Diameter External (in) a)	Minor Diameter Internal (in) b)	Minor Diameter Area (sq in)	Tensile Stress Area (sq in)
#0	0.06	80	0.0519	0.0451	0.0465	0.00151	0.0018
#1$	0.073	72	0.064	0.0565	0.058	0.00237	0.00278
#2	0.086	64	0.0759	0.0674	0.0691	0.00339	0.00394
#3*	0.099	56	0.0874	0.0778	0.0797	0.00451	0.00523
#4	0.112	48	0.0985	0.0871	0.0894	0.00566	0.00661
#5	0.125	44	0.1102	0.0979	0.1004	0.00716	0.0083
#6	0.138	40	0.1218	0.1082	0.1109	0.00874	0.01015
#8	0.164	36	0.146	0.1309	0.1339	0.01285	0.01474
#10	0.19	32	0.1697	0.1528	0.1562	0.0175	0.02
#12*	0.216	28	0.1928	0.1734	0.1773	0.0226	0.0258
1/4	0.25	28	0.2268	0.2074	0.2113	0.0326	0.0364
5/16	0.3125	24	0.2854	0.2629	0.2674	0.0524	0.058
3/8	0.375	24	0.3479	0.3254	0.3299	0.0809	0.0878
7/16	0.4375	20	0.405	0.378	0.3834	0.109	0.1187
1/2	0.5	20	0.4675	0.4405	0.4459	0.1486	0.1599
9/16	0.5625	18	0.5264	0.4964	0.5024	0.189	0.203
5/8	0.625	18	0.5889	0.5589	0.5649	0.24	0.256
3/4	0.75	16	0.7094	0.6763	0.6823	0.351	0.373
7/8	0.875	14	0.8286	0.79	0.7977	0.48	0.509
1	1	12	0.9459	0.9001	0.9098	0.625	0.663
1-1/8	1.125	12	1.0709	1.0258	1.0348	0.812	0.856
1 1/4	1.25	12	1.1959	1.1508	1.1598	1.024	1.073
1 3/8	1.375	12	1.3209	1.2758	1.2848	1.26	1.315
1 1/2	1.5	12	1.4459	1.4008	1.4098	1.521	1.581
Bolt Size	Major Diameter (in)	Threads per Inch (tpi)	Pitch Diameter (in)	Minor Diameter External (in) a)	Minor Diameter Internal (in) b)	Minor Diameter Area (sq in)	Tensile Stress Area (sq in)
* Secondary Size		a) Form for UNR thread			b) Basic Minor Diameter

Notes:

• a) For Class 2A threads with coating (plating) the max. is increased by the allowance, to the basic size. This is the same value as Class 3A.
• b) For uncoated hot-rolled, but not standard fasteners with cold rolled threads.
• c) UN series external thread, Max. Diameter, allows for Class 1A and 2A and basic for Class 3A.

Bo