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Torque Calculation

  • Published on Jan 30, 2025
  • 1 minute(s) read
  • Denis Tkalec
  • Tomislav Renic
  • Marko Bozac

For imperial:

For Metric:

Torque calculations:

Symbol

Name

UoM

Source

T

Torque

ft-lbs

Calculated.

Sb

Target Bolt Stress

psi

LOOKUP (based on Flange SIZE and CLASS RATING). If inputs missing then 70% of the Bolt Yield Stress is suggested. See Target Bolt Stress Lookup.

A

Bolt tensile stress area

in2

Calculated.

D

Bolt nominal diameter (stud size)

in

LOOKUP (based on Flange SIZE and CLASS RATING). See Stud Size Lookup.

K

Nut factor

dimensionless

User entered value. (Typically a value of 0.17 is used for uncoated studs properly lubricated with nickel-based anti-seize, and 0.12 for Teflon-coated studs is used.) 

Example:

Calculating the torque required for a bolt using both imperial and metric formulas.

Imperial Calculation if:

  • Target Bolt Stress (Sb): 73,505 psi

  • Bolt Tensile Stress Area (A): 0.969 in²

  • Stud Size (D): 1.25 in

  • Nut Factor (K): 0.12

Metric calculation if:

  • Target Bolt Stress (Sb): 560.8 MPa

  • Bolt Tensile Stress Area (A): 6.25 cm²

  • Stud Size (D): 31.75 mm

  • Nut Factor (K): 0.12