Enter the nominal diameter (in), the desired clamp load (lbf), and the coefficient of friction into the calculator to determine the Fastener Torque.

## Fastener Torque Formula

The following formula is used to calculate the Fastener Torque.

Tf = (D*P*K) / 12

• Where Tf is the Fastener Torque (lbf-ft)
• D is the nominal diameter (in)
• P is the desired clamp load (lbf)
• K is the coefficient of friction

## How to Calculate Fastener Torque?

The following example problems outline how to calculate Fastener Torque.

Example Problem #1

1. First, determine the nominal diameter (in). In this example, the nominal diameter (in) is determined to be .25 .
2. Next, determine the desired clamp load (lbf). For this problem, the desired clamp load (lbf) is measured to be 500 .
3. Next, determine the coefficient of friction. In this case, the coefficient of friction is found to be .85.
4. Finally, calculate the Fastener Torque using the formula above:

Tf = (D*P*K) / 12

Inserting the values from above and solving yields:

Tf = (.25*500*.85) / 12 = 8.85 (lbf-ft)

Example Problem #2

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

nominal diameter (in) = .75

desired clamp load (lbf) = 900

coefficient of friction = .40

Enter these given values yields:

Tf = (.75*900*.40) / 12 = 22.5 (lbf-ft)