Torque Wrench
A wrench that releases or indicates at a set torque. The only common hand tool that measures what it applied — which is what makes a specified tightening torque achievable at all.
What it does
- Tightening a joint to a specified torque
- Checking the torque on an assembled joint
- Any joint where the preload has been calculated
Fasteners it fits12 standards specify external hexagon
All standardsMatched on the drive form recorded against each standard, not on the tool's own claims — so this list changes when the fastener data changes, not when this paragraph does.
What to look forthe judgement calls, before the spec sheet
- The setting should sit in the middle of the tool's range, not at either end. Accuracy is quoted as a percentage of full scale, so a large wrench set near its minimum is the least accurate way to apply a small figure.
- Click, break-back and dial types all work; the difference is how the release is felt. Choose the one whose signal you can perceive in the position you actually work in.
- Accessories change the answer. An extension or a crow-foot alters the effective length and with it the applied torque, so a conversion is needed rather than a direct setting.
Misuse and safetythe ways this tool causes rework
- A torque wrench is not a breaker bar and not a general-purpose wrench. Breaking a seized fastener with one is how the calibration is destroyed.
- Turn the setting back to its minimum before storage. A spring left compressed loses its reference, and the error is silent — the tool still clicks, just at the wrong figure.
- The calculated torque is not the same as the achieved preload. Friction scatter means the clamp load can be tens of percent away from the figure, so a second check is worth more than a second decimal place.
Projects that call for itand what it is doing on each one
All projectsFrequently asked questions
How do I know what torque to set?
From the joint's specification: thread size, property class and the lubrication condition. The torque calculator on this site computes it from the thread geometry in this database and shows how far the figure moves with friction.
Does lubrication change the setting?
Substantially. Roughly 90% of applied torque goes into friction, so a lubricated thread reaches the same preload at a much lower torque. Setting a dry figure on a lubricated joint over-tensions it.
How often should it be recalibrated?
On a schedule, and after any overload or drop. The typical interval is annual for occasional use and more often in production, but a tool that has been used as a breaker bar should be checked before it is trusted for anything.