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Bolt Root and Tensile Stress Area
Fastener and Screw / Bolt Design, Formula & Calculations
Bolt Root and Tensile Stress Area Table for Metric and Inch Unit Threads
SI Metric Units |
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Bolt Size, Basic Thread Designation [Notes(1),(2)] |
Root Area, mm2 |
Tensile |
M14-2 |
102.1 |
115.4 |
M16-2 |
141.0 |
156.7 |
M20-2.5 |
220.4 |
244.8 |
M24-3 |
317.3 |
352.5 |
M27-3 |
419.1 |
459.4 |
M30-3 |
535.0 |
580.4 |
M33-3 |
665.1 |
715.6 |
M36-3 |
809.3 |
864.9 |
M39-3 |
976.6 |
1028 |
M42-3 |
1140 |
1206 |
M45-3 |
1327 |
1398 |
M48-3 |
1527 |
1604 |
M52-3 |
1817 |
1900 |
M56-3 |
2132 |
2222 |
M64-3 |
2837 |
2940 |
M70-3 |
3432 |
3545 |
M76-3 |
4083 |
4207 |
M82-3 |
4791 |
4925 |
M90-3 |
5822 |
5970 |
M95-3 |
6518 |
6674 |
M100-3 |
7253 |
7418 |
U.S.Customary Inch Units |
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Bolt Size, in. |
Threads per Inch |
Root Area, in.2 |
Tensile Stress |
|
Area ,in.2 |
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[Note(3)] |
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1⁄2 |
13 |
0.1257 |
0.1419 |
|
5⁄8 |
11 |
0.2017 |
0.2260 |
|
3⁄4 |
10 |
0.3019 |
0.3345 |
|
7⁄8 |
9 |
0.4192 |
0.4617 |
|
1 |
8 |
0.5509 |
0.6057 |
|
1 - 1⁄8 |
8 |
0.7276 |
0.7905 |
|
1 - 1⁄4 |
8 |
0.9289 |
0.9997 |
|
1 - 3⁄8 |
8 |
1.155 |
1.234 |
|
1 - 1⁄2 |
8 |
1.405 |
1.492 |
|
1 - 5⁄8 |
8 |
1.680 |
1.775 |
|
1 - 3⁄4 |
8 |
1.979 |
2.082 |
|
1 - 7⁄8 |
8 |
2.303 |
2.414 |
|
2 |
8 |
2.652 |
2.771 |
|
2 - 1⁄4 |
8 |
3.422 |
3.557 |
|
2 - 1⁄2 |
8 |
4.291 |
4.442 |
|
2 - 3⁄4 |
8 |
5.258 |
5.425 |
|
3 |
8 |
6.324 |
6.506 |
|
3 - 1⁄4 |
8 |
7.487 |
7.686 |
|
3 - 1⁄2 |
8 |
8.748 |
8.963 |
|
3 - 3⁄4 |
8 |
10.11 |
10.34 |
|
4 |
8 |
11.57 |
11.81 |
NOTES:
(1) Metric thread designations are given in bolt size (mm) and pitch (mm) (e.g., M14-2 refers to a 14 mm diameter bolt with a 2 mm pitch
thread).
(2) The side-by-side placement of the two tables is not meant to infer direct conversion between the listed SI and U.S. Customary units.
(3) The root and tensile stress areas are based on coarse-thread series for sizes M27 and smaller, and 3 mm pitch thread series for sizes
M30 and larger (coarse-thread series for sizes 1 in. and smaller, and 8-pitch thread series for sizes 1- 1⁄8 in. and larger).