Shapes and Dimensions of Hex Socket Set Screws (Excerpt from JIS B 1177-1997)

2026/04/06

[Scope of Application]

This standard specifies hexagon socket set screws with nominal sizes ranging from M1.6 to M24 and a material grade of A.

*This page provides an overview of screw tip shapes, specifically "flat tips" and "recessed tips."

[Flat Tip]

Nominal diameter (d)			M1.6	M2	M2.5	M3	M4	M5	M6	M8	M10	M12	M16	M20	M25
Pitch (P)			0.35	0.4	0.45	0.5	0.7	0.8	1	1.25	1.5	1.75	2	2.5	3
dp	Max		0.80	1.00	1.50	2.00	2.50	3.5	4.0	5.5	7.00	8.50	12.00	15.00	18.00
dp	Minimum		0.55	0.75	1.25	1.75	2.25	3.2	3.7	5.2	6.64	8.14	11.57	14.57	17.57
df			Approximate thread pitch
e * 3	Minimum		0.809	1.011	1.454	1.733	2.303	2.873	3.443	4.583	5.723	6.863	9.149	11.429	13.716
S * 4	Nominal		0.7	0.9	1.3	1.5	2	2.5	3	4	5	6	8	10	12
	Max		0.724	0.913	1.300	1.58	2.08	2.58	3.08	4.095	5.14	6.14	8.175	10.175	12.212
	Minimum		0.710	0.887	1.275	1.52	2.02	2.52	3.02	4.020	5.02	6.02	8.025	10.025	12.032
t	Minimum * 5		0.7	0.8	1.2	1.2	1.5	2	2	3	4	4.8	6.4	8	10
t	Minimum * 6		1.5	1.7	2	2	2.5	3	3.5	5	6	8	10	12	15
L	(Reference) Approximate mass per 1,000 pieces, in kg (Density: 7.85 kg/dm³)
L	Nominal length	Minimum	Max
2	1.8	2.2	0.021	0.029
2.5	2.3	2.7	0.025	0.037	0.063
3	2.8	3.2	0.029	0.044	0.075	0.1
4	3.76	4.24	0.037	0.059	0.1	0.14	0.22
5	4.76	5.24	0.046	0.074	0.125	0.18	0.3	0.44
6	5.76	6.24	0.054	0.089	0.15	0.22	0.38	0.56	0.76
8	7.71	8.29	0.07	0.119	0.199	0.3	0.54	0.8	1.11	1.89
10	9.71	10.29		0.148	0.249	0.38	0.7	1.04	1.46	2.52	3.78
12	11.65	12.35			0.299	0.46	0.86	1.28	1.81	3.15	4.78	6.8
16	15.65	16.35				0.62	1.18	1.76	2.51	4.41	6.78	9.6	16.3
20	19.58	20.42					1.49	2.24	3.21	5.67	8.76	12.4	21.5	32.3
25	24.58	25.42						2.84	4.09	7.25	11.2	15.9	28	42.6	57
30	29.58	30.42							4.97	8.82	13.7	19.4	34.6	52.9	72
35	34.5	35.5								10.4	16.2	22.9	41.4	63.2	87
40	39.5	40.5								12	18.7	26.4	47.7	73.5	102
45	44.5	45.5									21.2	29.9	54.2	83.8	117
50	49.5	50.5									23.7	33.4	60.7	94.1	132
55	54.4	55.6										36.8	67.3	104	147
60	59.4	60.6										40.3	73.7	115	162

[Screw Tip]

Nominal diameter (d)			M1.6	M2	M2.5	M3	M4	M5	M6	M8	M10	M12	M16	M20	M25
Pitch (P)			0.35	0.4	0.45	0.5	0.7	0.8	1	1.25	1.5	1.75	2	2.5	3
dz	Max		0.80	1.00	1.20	1.40	2.00	2.50	3.00	5.0	6.0	8.05	10.00	14.00	16.00
dz	Minimum		0.55	0.75	0.95	1.15	1.75	2.25	2.75	4.7	5.7	7.64	9.64	13.57	15.57
df			Approximate thread root diameter
e * 3	Minimum		0.809	1.011	1.454	1.733	2.303	2.873	3.443	4.583	5.723	6.863	9.149	11.429	13.716
S * 4	Nominal		0.7	0.9	1.3	1.5	2	2.5	3	4	5	6	8	10	12
	Max		0.724	0.913	1.300	1.58	2.08	2.58	3.08	4.095	5.14	6.14	8.175	10.175	12.212
	Minimum		0.710	0.887	1.275	1.52	2.02	2.52	3.02	4.020	5.02	6.02	8.025	10.025	12.032
t	Minimum * 5		0.7	0.8	1.2	1.2	1.5	2	2	3	4	4.8	6.4	8	10
t	Minimum * 6		1.5	1.7	2	2	2.5	3	3.5	5	6	8	10	12	15
L	(Reference) Approximate mass per 1,000 pieces, in kg (Density: 7.85 kg/dm³)
L	Nominal length	Minimum	Max
2	1.8	2.2	0.019	0.029
2.5	2.3	2.7	0.025	0.037	0.063
3	2.8	3.2	0.029	0.044	0.075	0.1
4	3.76	4.24	0.037	0.059	0.1	0.14	0.23
5	4.76	5.24	0.046	0.074	0.125	0.18	0.305	0.42
6	5.76	6.24	0.054	0.089	0.15	0.22	0.38	0.54	0.74
8	7.71	8.29	0.07	0.119	0.199	0.3	0.53	0.78	1.09	1.88
10	9.71	10.29		0.148	0.249	0.38	0.68	1.02	1.44	2.51	3.72
12	11.65	12.35			0.299	0.46	0.83	1.26	1.79	3.14	4.73	6.7
16	15.65	16.35				0.62	1.13	1.74	2.49	4.4	6.73	9.5	15.7
20	19.58	20.42					1.4	2.22	3.19	5.66	8.72	12.3	20.9	31.1
25	24.58	25.42						2.82	4.07	7.24	11.2	15.8	27.4	41.4	55.2
30	29.58	30.42							4.94	8.81	13.7	19.3	33.9	51.7	70.3
35	34.5	35.5								10.4	16.2	22.7	40.4	62	85.3
40	39.5	40.5								12	18.7	26.2	46.9	72.3	100
45	44.5	45.5									21.2	29.7	53.3	82.6	115
50	49.5	50.5									23.6	33.2	59.8	92.6	130
55	54.4	55.6										36.6	66.3	103	145
60	59.4	60.6										40.1	72.8	114	160

Note

The recommended nominal length for a screw shall be as specified in the section on mass.
*1: For nominal lengths ℓ indicated by the stepped shading in the table above, apply a 120° chamfer.
*2: The angle of approximately 45° applies to the tapered section below the diameter of the thread groove.
*3: e_(min) = 1.14 × s_(min)
*4: Gauge inspections for e and s are conducted in accordance with JIS B 1016.
*5: The minimum value in the top row applies to screws with the nominal length indicated by the shading.
*6: The minimum value in the bottom row applies to screws with a nominal length without a shank.
*7: The rim of the hexagonal hole may have a slight rounding or chamfer.
The bottom of the hexagonal hole may be finished with a reamer. If a reamer is used, the remaining depth of the drilled hole must not exceed one-third of the length of the hexagonal side (e/2).

Other Technical Documents