Dimensions in milimeters

Lower nut (tightening nut) Upper nut
(locking nut)
S H (lower nut) H1 (upper nut) B (width) C l(total height) h Set/
Weight
Material classification: Tightening torque
standard reference value list (Unit: Nm)
Materials are uniform
Margin Coarse Fine Standard dimensions Tolerance Standard dimensions Tolerance Standard dimensions Tolerance Approx Approx Approx g Class4 (SS400 or equivalent) Class8 (S45C or equivalent) Class10 (SCM435 or equivalent) A2,A4
(SUS304, 306 or equivalent)
Tightening torque (Unit Nm)
4.8(320N/m㎡) 8.8(640N/m㎡) 10.9(900N/m㎡) 50(210N/m㎡)
Cutting and hot-worked bolts
70(450N/m㎡)
Cold and warm-worked bolts
M6 1.0 - 5 0
-0.48
5 0
-0.48
10 0
-0.6
11.5 8.3 3.3 3.3 2.3~6 - - 1.5~4 3.3~9 4~5
M8 1.25 1.0 6.5 0
-0.58
6.5 0
-0.58
13 0
-0.7
15 11 4.5 8.6 5.6~15 11.2~30 15.8~42 3.7~10 7.9~21 9~13
M10 1.5 1.25 8 // 8 // 17 // 19.6 13.5 5.5 17.6 11~30 22~59 31~84 7~20 16~42 18~24
M12 1.75 1.5 10 // 10 // 19 0
-0.8
21.9 17 7.0 27.3 19~52 39~104 55~146 13~34 27~73 27~39
M14 2.0 1.5 11 0
-0.7
11 0
-0.7
22 // 25.4 18.5 7.5 39 31~82 62~165 87~232 20~54 44~116 40~58
M16 2.0 1.5 13 // 13 // 24 // 27.7 22.5 9.5 52.8 48~129 97~257 136~362 32~84 68~181 70~100
M18 2.5 1.5 15 // 15 // 27 // 31.2 25.5 10.5 80 66~177 133~354 187~498 44~116 93~249 100~150
M20 2.5 1.5 16 // 16 // 30 // 34.6 27.5 11.5 105 94~251 188~502 265~706 62~165 132~353 120~200
M22 2.5 1.5 18 // 18 // 32 0
-1.0
37 31.5 13.5 130 128~341 256~683 360~960 84~224 180~480 150~250
M24 3.0 2.0 19 0
-0.84
19 0
-0.84
36 // 41.6 33 14 180 163~434 325~868 458~1220 107~285 229~610 160~300
M27 3.0 2.0 22 0
-1.84
22 0
-1.84
41 // 47.3 38 16 246 238~635 458~1269 669~1785 156~416 335~892 250~390
M30 3.5 2.0 24 0
-1.84
24 0
-1.84
46 // 53.1 42 18 375 323~862 646~1723 909~2424 212~566 454~1212 270~440
M33 3.5 2.0 26 0
-1.84
26 0
-1.84
50 // 57.7 46 20 480 440~1173 879~2345 1237~3298 289~770 618~1649 290~490
M36 4.0 3.0 29 0
-1.84
29 0
-1.84
55 0
-1.2
63.5 50 21 630 565~1506 1129~3012 1588~4235 371~988 794~2118 340~590
M39 4.0 3.0 31 0
-2.0
31 0
-2.0
60 & 69.3 54 23 935 731~1949 1462~3898 2056~5481 480~1279 1028~2741 390~640
M42 4.5 4.0 34 0
-2.0
34 0
-2.0
65 // 75 59 25 1080 904~2411 1808~4821 2542~6780 593~1582 1271~3390 440~690
M45 4.5 4.0 36 0
-2.0
36 0
-2.0
70 // 80.8 63 27 1330 1128~3309 2257~6018 3174~8463 741~1975 1587~4231 490~740
M48 5.0 4.0 38 0
-2.0
38 0
-2.0
75 // 86.5 67 29 1595 1358~3620 2715~7240 3818~10181 891~2376 1909~5091 540~780
M52 5.0 4.0 42 0
-2.0
42 0
-2.0
80 // 92.4 75 33 2055 1755~4681 3510~9361 4937~13164 1152~3072 2468~6582 590~830
M56 5.5 4.0 45 0
-2.0
45 0
-2.0
85 0
-1.4
98.1 79 34 2410 2183~5820 4365~11641 6139~16370 1432~3820 3069~8185 640~880
M64 6.0 4.0 51 0
-2.2
51 0
-2.2
95 // 110 89 38 3172 3288~8769 6577~17537 9248~24662 2158~5755 4624~12331 690~930
The tightening torque value is uniform in both the semi-thin and thin types regardless of the material used.
*The screw standard is based on JIS BO205 and JIS BO207, and the nut standard is based on JIS B1181.


At least M8 for hot dipped zinc plating.

The minimum preload of the above-mentioned lower nuts are 60% of the bolt's yield tensile strength, given the torque constant of 0.1. The maximum preload cannot exceed 80% of the bolt's yield tensile strength with a given torque constant of 0.2.

The torque constant is 0.1 when oil is applied to the nuts and bolts, and when oil is not applied, the torque constant is 0.2.

Materials equivalent to SS400:
SWRM - mild steel wire rods, SWRH - hard steel wire rods, SWRCH - cold heading steel wire rod, SWCH - cold heading steel wire [NOTE: These are the same as above]

  • torque axial force simplified calculation formula
  • T=K×d×Ff
  • T:tightening torque
  • Ff:axial force
  • K:torque coefficient
  • d:nominal screw diameter

Tightening Torque Table: Detailed tightening torques by material size


N.B. For thinner materials, use 75% of the tightening torque. This applies to the upper (concave) nut as well.