Torque Wrench Extension Calculator
Calculate the adjusted torque setting when using a torque wrench extension or crow's foot adapter.
Adjusted Torque Setting
When using an extension on a torque wrench, the effective lever arm changes, requiring an adjusted torque setting.
Adjusted Torque = Desired Torque × (Wrench Length / (Wrench Length + Extension Length))
This formula applies when the extension is mounted at an angle (like a crow’s foot). If the extension is inline (straight), no adjustment is needed.
When to adjust:
- Crow’s foot wrench at 90° to handle: YES, adjust
- Straight extension bar: NO adjustment needed
- Adapter at an angle: YES, adjust
Common torque specs:
- Lug nuts (passenger car): 80-100 ft-lbs
- Spark plugs: 12-18 ft-lbs
- Oil drain plug: 25-35 ft-lbs
- Cylinder head bolts: 60-90 ft-lbs (varies widely)