Calculate wrench torque, hand force, or lever length in metric and imperial units, then correct a torque-wrench setting for an angled crowfoot extension.

90ยฐ is perpendicular. At 0ยฐ or 180ยฐ, forward torque is zero and inverse force/length is undefined.

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Wrench Torque Formula

The following formula is used to calculate the Wrench Torque.

Tw = F ร— R ร— sin(af), with af measured in degrees between the lever and force.

  • Where Tw is the Wrench Torque (N-m)
  • F is the total force applied to the wrench (N) 
  • af is the angle between the lever and applied force (degrees) 
  • R is the length of the wrench (m) 

For a fixed crowfoot adapter, the calculator also uses Tsetting = Tdesired ร— L รท (L + E cos ฮธ), assuming hand force perpendicular to the wrench at its calibrated grip point. Measure L from drive center to grip center and E from drive center to fastener center. At 0ยฐ the adapter extends away from the grip; at 90ยฐ no lever-length correction is needed. Follow the wrench and adapter manufacturerโ€™s instructions.

How to Calculate Wrench Torque?

The following example problems outline how to calculate Wrench Torque.

Example Problem #1

  1. First, determine the total force applied to the wrench (N). In this example, the total force applied to the wrench (N) is determined to be 15.
  2. Next, determine the direction of force applied to the wrench (deg). For this problem, the direction of force applied to the wrench (deg) is measured to be 45.
  3. Next, determine the length of the wrench (m). In this case, the length of the wrench (m) is found to be .10.
  4. Finally, calculate the Wrench Torque using the formula above: 

Tw = F * sin(af) * R

Inserting the values from above and solving yields: 

Tw = 15 ร— sin(45ยฐ) ร— 0.10 โ‰ˆ 1.061 Nยทm

Example Problem #2

Using the same method as above, determine the variables required by the formula. For this example problem, these are:

total force applied to the wrench (N) = 16

direction of force applied to the wrench (deg) = 40

length of the wrench (m) = .75

Entering these given values into the calculator or the formula above yields: 

Tw = 16 * sin(40deg) * .75 = 7.713 (N-m)