Shapes and Dimensions of Hexagonal Wrenches (Hex Wrenches/L-Wrenches/Hex Wrenches) (Excerpt from JIS B 4648:2008)

2026/05/07

Width s mm			Diagonal distance e(a) mm		Length of long arm ℓ1 mm				Short side length 2ℓ mm		Minimum Rockwell hardness	Minimum guaranteed torque
Nominal	Maximum	Minimum	Maximum	Minimum	Standard Type	M-type	L-type	Tolerance	Reference dimensions	Tolerance	Minimum Rockwell hardness	Minimum guaranteed torque
0.7	0.71	0.70	0.79	0.76	33	-	-	0–2	7	0-2	52	0.08
0.9	0.89	0.88	0.99	0.96	33	-	-	0–2	11	0-2	52	0.18
1.3	1.27	1.24	1.42	1.37	41	63.5	81	0–2	13	0-2	52	0.53
1.5	1.50	1.48	1.68	1.63(b)	46.5	63.5	91.5	0–2	15.5	0-2	52	0.82
2	2.00	1.96	2.25	2.18(c)	52	77	102	0–2	18	0-2	52	1.9
2.5	2.50	2.46	2.82	2.75(c)	58.5	87.5	114.5	0–4	20.5	0-2	52	3.8
3	3.00	2.96	3.39	3.31(c)	66	93	129	0–4	23	0-2	52	6.6
4	4.00	3.95	4.53	4.44(c)	74	104	144	0–4	29	0-2	52	16
5	5.00	4.95	5.67	5.58(d)	85	120	165	0–4	33	0-2	52	30
6	6.00	5.95	6.81	6.71(d)	96	141	186	0–6	38	0-2	52	52
8	8.00	7.94	9.09	8.97	108	158	208	0–6	44	0-2	52	120
10	10.00	9.94	11.37	11.23	122	180	234	0–6	50	0-2	48	220
12	12.00	11.89	13.65	13.44	137	202	262	0–6	57	0-2	48	370
14	14.00	13.89	15.93	15.70	154	229	294	0–7	70	0-3	48	590
17	17.00	16.89	19.35	19.09	177	262	337	0–7	80	0-3	45	980
19	19.00	18.87	21.63	21.32	199	-	-	0–7	89	0-3	45	1360
22	22.00	21.87	25.05	24.71	222	-	-	0–12	102	0–5	45	2110
24	24.00	23.87	27.33	26.97	248	-	-	0–12	114	0–5	45	2750
27	27.00	26.87	30.75	30.36	277	-	-	0–12	127	0–5	45	3910
32	32.00	31.84	36.45	35.98	347	-	-	0–12	157	0–5	45	4,000
36	36.00	35.84	41.01	40.50	391	-	-	0–12	176	0–5	45	4,000
41	41.00	40.84	46.71	46.15	435	-	-	0–12	195	0–5	45	4000
46	46.00	45.84	52.41	51.80	480	-	-	0–12	215	0–5	45	4,000

* (a) e_(max) = 1.14s_(max) – 0.03 (1.5 ≤ s ≤ 46) *
(a) e_(min) = 1.13s_(min)(8 ≤ s ≤ 46)
* (b) e min = 1.13s min
– 0.04 * (c) e min = 1.13s min – 0.03 * (d) e min = 1.
13s min – 0
.02 * The spanner is hardened all the way to the center of the shaft along its entire length.
* For s ≤ 27 mm, Md is calculated using the formula Md = 0.8(5 × 0.7Rm)(0.224 × 5s³). Note that Rm is the tensile strength approximated from the minimum Rockwell hardness of the spanner.

Notes

Chamfering the end of a wrench

The end of the wrench does not need to be chamfered if it can be easily inserted into a hex socket. However, if a chamfer is applied, it should be done as shown in the figure on the right, ensuring that a width of two flanks (s) remains on the end face.
Furthermore, the sides of both the long and short shanks must be perpendicular to their respective axes and must not be tilted by more than ±4° (see figure on the right).

Guaranteed torque for strength class 45H (for reference)

Nominal screw size d	Guaranteed torque [N·m]	Recommended tightening torque [N·m]	Wrench size
M1.6	0.07	0.04	0.7
2	0.15	0.09	0.9
2.5	0.44	0.26	1.3
(2.6)	0.44	0.26	1.3
3	1.17	0.69	1.5
4	2.74	1.67	2
5	5.88	3.53	2.5
6	9.8	5.9	3
8	23.5	14.2	4
10	45.1	27.5	5
12	77.5	47.1	6
(14)	88.3	53.0	6
16	186	118	8
(18)	211	128	8
20	363	216	10

Shapes and Dimensions of Hexagonal Wrenches (Hex Wrenches/L-Wrenches/Hex Wrenches) (Excerpt from JIS B 4648:2008)

Notes

Guaranteed torque for strength class 45H (for reference)

Other Technical Documents

Specifications

Hole Machining, Tolerances, and Fits

Calculations, Conversions, Formulas, and Units

Machine Elements

Material Properties

Terminology