Torque Wrench Calibration in 6 Steps

When was the last time you calibrated your torque wrench? Do you sincerely believe that your torque wrench is as accurate as possible? How often do you calibrate your torque wrench?

There is a high chance you haven't given your torque wrench enough thought to answer such questions. It is safe to say that a torque wrench is one of the most overlooked tools we own.

A device used to fasten a nut or bolt, a torque wrench is an inexpensive tool that ensures that our car tires stay put. Even though it performs such a crucial function, no one pays much attention to its calibration. Why? This is because people are not aware of the importance of torque wrench calibration.

What does calibration entail?

Calibrating a tool involves adjusting the standard readings of the tool by comparison with the standard. The method allows for checking the accuracy of the tool.

If your torque wrench is not calibrated correctly, it will provide you with an accurate measure of torque. If you use your faulty torque wrench, you will either under torque or over torque, which may lead to dangerous outcomes for your beloved car and its passengers.

Therefore, it is integral for you to know how to perform torque wrench calibration. Let us provide you with an overview of the steps that you should follow.

How to calibrate torque wrenches

While there are numerous professionals who are equipped at calibrating torque wrenches, unless you plan on using the tool on a plane, you can risk doing it on your own. After all, it is always better to be self-reliant. If you think you are well equipped for the task, you can easily calibrate torque wrench by following a few simple steps.

The instruments that you will require may include the following:

  • A bench vise to clamp the torque wrench
  • A weight (20 pounds) to provide a force
  • A tape measure to measure the distance
  • A sharpie or marker to make markings

Step 1: Understand how calibration is done

How would you feel if a doctor operated on you without even looking at your case? Unless you wish to die, you will probably not let him/her operate on you. Similarly, before delving into any task, it is imperative that you know as much about it as possible. While there is no parallel between a simple calibration process and surgery, the fact remains that you need to be well equipped for whatever task you perform.

Therefore, in order to successfully calibrate your torque wrench, you should understand the intricacies of the process. The formula used for the adjustment is torque = force multiplied by distance. The load you place on the bolt depends on various factors including friction. For instance, if the bolt you are fastening is well oiled, you will have to apply a larger load.

A DIY calibration of a torque wrench can be done via a bench vise by using a 20-pound weight, a measuring tape, and a thin string. Now the actual calibration process begins.

Step 2: Measure the mark

torque wrench calibration

To match to the middle of the square drive, create a mark on the backside of the torque wrench. By measuring the distance between the handle and where you normally grab the wrench, you will make another marking.

torque wrench calibration

The distance between the two markings should then be measured via the measuring tape.

Step 3: Place the wrench firmly on the vice

torque wrench calibration

After clamping the square drive on to the vice, you need to make sure that no other part of the torque wrench touches the clamp. Once you have made sure of this, the handle of the wrench should be rotated to a horizontal position and set the torque value to whatever the appropriate setting is.

Step 4: Locate the point of transition

torque wrench calibration

Place the weight on the line you made during the second stage. Once you hear a clicking sound, the weight should be lifted and brought towards the square drive, a little distance at a time. This procedure should be continued until the clicking sound diminishes. Mark the point where the clicking sound is not heard and mark the point where it is. This will help you locate the point of transition.

Step 5: Measure the point of transition

torque wrench calibration

After locating the transition point, measure the distance from the point of transition to the square drive. This will give you the value of the ratio required for the calculations.

Step 6: Plug the data into the equation

torque wrench calibration

Divide the two distances measured to get the required ratio. The answer of this will then be multiplied by the torque you desire.

While conducting the calibration process, you need to be aware of various factors which may affect the result of the calibration. Such factors include the temperature the tool is usually used at. By paying heed to the temperature during calibration, you will avoid errors.


Following the above mentioned steps will help in successfully calibrating a torque wrench.

Moreover, you should take steps to ensure maximum life of your torque wrench. Such steps include storing the tool in a dry area. Furthermore, you should reverse your torque setting to low before storing it and never wrench the tool past the clicking sound. All such measures will lead to a better life of the product. This, together with appropriate calibration, will ensure that you gain maximum value from the tool.

All in all, you don’t need a professional to do the calibration for you. All you need is a little knowledge of physics and determination, and you can do it on your own.

Regardless of whether you decide to calibrate your torque wrench through a professional or by yourself, the fact remains that the procedure itself is highly important. In order to avoid any unfavorable outcomes, it is best that you take all the necessary measures to exemplify the quality of your torque wrench. Calibrating it is one of these measures. Calibrate your own torque wrench and be resourceful. 

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