Proto torque adapters are designed with a center-to-center dimension of 2". This means that the distance from the center of the square drive of the mating torque wrench to the center of the fasteners is exactly 2". This constant dimension serves to simplify the process of calculating the torque applied.

The steps as required to calculate torque when using a Proto torque adapter are as follows:

1. Determine the amount of torque required to properly set the fastener.
2. Determine the length of the torque wrench from the center of the grip to the center of the square drive (remember that this changes as you adjust the torque wrench setting).
3. Multiply the amount of torque you are trying to apply (1) by the length of the torque wrench from (2) above.
4. Add 2" for the torque adapter length to (2).
5. Divide the result from (3) by the result from (4). The result is the torque wrench setting required to properly torque the fastener.

For example, you want to torque a grade 8 fastener with a thread diameter of 3/8" and a hex size of 9/16", using a Proto 6006AB torque wrench.

1. From the Standard Torque Value Chart the recommended bolt torque is 47 foot-pounds.
2. The 6006AB torque wrench dimension is 10".
3. The torque, 47 foot-pounds, multiplied by the length of 10 inches is 470.
4. Adding 2" for the torque adapter to the torque wrench length of 10" equals 12".
5. Dividing 470 by 12 results in a torque wrench setting of 39 foot-pounds. This will result in the desired 47 foot-pounds at the fastener.

Following this procedure results in an accuracy of ±2% (added to the accuracy of the torque wrench it becomes W6% total). For greater accuracy, another iteration can be performed using a measurement of the torque wrench from the center of the grip (set at 39 foot-pounds) to the center of the square drive.