# Fastener Torque Calculator, Formula, Fastener Torque Calculation

## Fastener Torque Calculator:

Enter the values of torque coefficient, K, desired preload in pounds, P(lb) and nominal diameter D(in) of the fastener to determine the value of Fastener torque, Tf(lb-in).

 Enter Desired Preload: lb Enter Nominal Diameter: in Enter Torque Coefficient: Result – Fastener Torque: lb-in

## Fastener Torque Formula:

Fastener torque refers to the rotational force applied to a fastener, such as a screw, bolt, or nut, to achieve a desired level of tension and secure mechanical parts together.

Fastener torque, Tf(lb-in) in is calculated by dividing the product of torque coefficient, K, desired preload in pounds, P(lb) and nominal diameter D(in) of the fastener in inches by 12.

Fastener torque, Tf(lb-in) = D(in) * K * P(in) / 12

Tf(lb-in) = Fastener torque in pound inches, lb-in.

P(lb) = desired preload in pounds, lb.

D(in) = nominal diameter in inches, in

K = torque coefficient.

Fastener Torque Calculation:

1. For a bolt with a nominal diameter of 0.5 inches, requiring a preload of 10000 pounds and a torque coefficient of 0.2, calculate the fastener torque.
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Given: P(lb) = 10,000 pounds,  D(in) = 0.5 inches, K = 0.2.

Fastener torque, Tf(lb-in) = D(in) * K * P(in) / 12

Tf(lb-in) = 0.5 * 0.2 * 10000 / 12

Tf(lb-in) = 83.33lb-in.

1. A mechanic needs to apply a preload of 8000 pounds using a bolt inches and a torque coefficient of 0.15. The required fastener torque is 25lb-in, find the nominal diameter in inches.

Given: T f(lb-in) = 25lb-in, K = 0.15, P(lb) = 8000 pounds

Fastener torque, Tf(lb-in) = D(in) * K * P(in) / 12

D(in) = Tf(lb-in) * 12 / K * P(in)

D(in) =25 * 12 / 0.15 * 8000

D(in) =0.25 inches.