ASME B18.3 dimensions — Hexagon socket head cap screws, inch series (Table 1 profile)

2012 edition, current · 32 sizes, #4-40 UNC – 1-12 UNF see the cross-reference →

We supply to ASME B18.3. Name it on your order.

ASME B18.3 dimensions

Thread size	dBasic Major Diameter (in)	TPIThreads Per Inch	Thread Series	Thread Class	d maxBody Diameter Max (in)	d minBody Diameter Min (in)	dkHead Diameter (in)	dkHead Diameter (min) (in)	kNominal Head Height (in)	kHead Height (min) (in)	CHead Chamfer (max) (in)	sHex Socket Size (in)	TKey Engagement (min) (in)	GSocket Wall (min) (in)	RUnderhead Radius (max) (in)
#4-40 UNC	0.112	40	UNC	3A	0.112	0.1075	0.183	0.176	0.112	0.108	0.009	0.094	0.051	0.038	0.008
#4-48 UNF	0.112	48	UNF	3A	0.112	0.1075	0.183	0.176	0.112	0.108	0.009	0.094	0.051	0.038	0.008
#5-40 UNC	0.125	40	UNC	3A	0.125	0.1202	0.205	0.198	0.125	0.121	0.012	0.094	0.057	0.043	0.008
#5-44 UNF	0.125	44	UNF	3A	0.125	0.1202	0.205	0.198	0.125	0.121	0.012	0.094	0.057	0.043	0.008
#6-32 UNC	0.138	32	UNC	3A	0.138	0.1329	0.226	0.216	0.138	0.134	0.013	0.109	0.064	0.047	0.008
#6-40 UNF	0.138	40	UNF	3A	0.138	0.1329	0.226	0.216	0.138	0.134	0.013	0.109	0.064	0.047	0.008
#8-32 UNC	0.164	32	UNC	3A	0.164	0.1585	0.27	0.257	0.164	0.159	0.014	0.141	0.077	0.056	0.008
#8-36 UNF	0.164	36	UNF	3A	0.164	0.1585	0.27	0.257	0.164	0.159	0.014	0.141	0.077	0.056	0.008
#10-24 UNC	0.19	24	UNC	3A	0.19	0.184	0.312	0.298	0.19	0.185	0.018	0.156	0.09	0.065	0.008
#10-32 UNF	0.19	32	UNF	3A	0.19	0.184	0.312	0.298	0.19	0.185	0.018	0.156	0.09	0.065	0.008
#12-24 UNC	0.216	24	UNC	3A	0.216	0.2095	0.324	0.314	0.216	0.21	0.022	0.156	0.103	0.082	0.01
#12-28 UNF	0.216	28	UNF	3A	0.216	0.2095	0.324	0.314	0.216	0.21	0.022	0.156	0.103	0.082	0.01
1/4-20 UNC	0.25	20	UNC	3A	0.25	0.2435	0.375	0.354	0.25	0.244	0.025	0.188	0.12	0.095	0.01
1/4-28 UNF	0.25	28	UNF	3A	0.25	0.2435	0.375	0.354	0.25	0.244	0.025	0.188	0.12	0.095	0.01
5/16-18 UNC	0.3125	18	UNC	3A	0.3125	0.3053	0.469	0.446	0.312	0.306	0.033	0.25	0.151	0.119	0.01
5/16-24 UNF	0.3125	24	UNF	3A	0.3125	0.3053	0.469	0.446	0.312	0.306	0.033	0.25	0.151	0.119	0.01
3/8-16 UNC	0.375	16	UNC	3A	0.375	0.3678	0.562	0.54	0.375	0.368	0.04	0.312	0.182	0.143	0.01
3/8-24 UNF	0.375	24	UNF	3A	0.375	0.3678	0.562	0.54	0.375	0.368	0.04	0.312	0.182	0.143	0.01
7/16-14 UNC	0.4375	14	UNC	3A	0.4375	0.4294	0.656	0.631	0.438	0.43	0.047	0.375	0.213	0.166	0.015
7/16-20 UNF	0.4375	20	UNF	3A	0.4375	0.4294	0.656	0.631	0.438	0.43	0.047	0.375	0.213	0.166	0.015
1/2-13 UNC	0.5	13	UNC	3A	0.5	0.4919	0.75	0.725	0.5	0.492	0.055	0.375	0.245	0.19	0.015
1/2-20 UNF	0.5	20	UNF	3A	0.5	0.4919	0.75	0.725	0.5	0.492	0.055	0.375	0.245	0.19	0.015
9/16-12 UNC	0.5625	12	UNC	3A	0.5625	0.5538	0.843	0.827	0.562	0.554	0.062	0.437	0.276	0.214	0.015
9/16-18 UNF	0.5625	18	UNF	3A	0.5625	0.5538	0.843	0.827	0.562	0.554	0.062	0.437	0.276	0.214	0.015
5/8-11 UNC	0.625	11	UNC	3A	0.625	0.6163	0.938	0.914	0.625	0.616	0.07	0.5	0.307	0.238	0.015
5/8-18 UNF	0.625	18	UNF	3A	0.625	0.6163	0.938	0.914	0.625	0.616	0.07	0.5	0.307	0.238	0.015
3/4-10 UNC	0.75	10	UNC	3A	0.75	0.7406	1.125	1.094	0.75	0.74	0.085	0.625	0.37	0.285	0.015
3/4-16 UNF	0.75	16	UNF	3A	0.75	0.7406	1.125	1.094	0.75	0.74	0.085	0.625	0.37	0.285	0.015
7/8-9 UNC	0.875	9	UNC	3A	0.875	0.8647	1.312	1.291	0.875	0.864	0.1	0.75	0.432	0.333	0.02
7/8-14 UNF	0.875	14	UNF	3A	0.875	0.8647	1.312	1.291	0.875	0.864	0.1	0.75	0.432	0.333	0.02
1-8 UNC	1	8	UNC	3A	1	0.9886	1.5	1.476	1	0.988	0.114	0.75	0.495	0.38	0.02
1-12 UNF	1	12	UNF	3A	1	0.9886	1.5	1.476	1	0.988	0.114	0.75	0.495	0.38	0.02

32 of 32 sizes shown.

ASME B18.3 sizes

9 diameters · weight and hole sizes live on each size page

#6-32 UNC #8-32 UNC #10-24 UNC 1/4-20 UNC 5/16-18 UNC 3/8-16 UNC 1/2-13 UNC 5/8-11 UNC 3/4-10 UNC All 151 sizes in this family →

What we supply to ASME B18.3

2 materials

Material	Property class	Finish
Alloy Steel	—	Blackened · Plain
Stainless Steel	AF · CW	Plain · Passivated

Equivalents and mating parts

ASME B1.1-2024 →ASTM A574 →ASTM F837 →Hexagon socket head cap screws — inch series (Table 1 profile) sizes and weights →

To ASME B18.3Socket Flat Countersunk Head Cap Screw ASME B18.3

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