Related Resources: calculators

Thread Yield and Tensile Strength Equation and Calculator

Fastener and Screw / Bolt Design, Formula and Calculations

The following Equation and Calculator will determine the working loads base on the ultimate yield strength threaded connections.

Tensile Stress-Strain Diagram For Bolt

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Ultimate Strength of a thread

ymin = syield x a

Ultimate Tensile Strength of a thread

stensile = tmin x a

Shear Strength of a thread

Ssy = pr x syield


ymin = Minimum Yield of bolt threads engaged (lbs)

syield = Minimum yield strength of the bolt grade, ASTM, SAE, etc. (psi)

stensile = Ultimate Yield Strength (lbs)

tmin = Minimum tensile strength of the bolt grade, ASTM, SAE, etc. (psi)

Ssy = Working axial load of fastener bolt (lbs)

a = Stress area of thread (in2)

pr = Percent expressed as decimal, e.g. 60% = 0.6 - This is the factor of safety (FOS) for the design application