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Torque wrench extension calculator: what to set

An extension changes the lever arm: get the value to set on the torque wrench so the bolt sees the required torque, T·L/(L + E). Free, instant result.

  • Instant result
  • Formula and standards shown
  • On desktop and phone

Pre-filled example

A required torque of 100 N·m with a 400 mm wrench and a 100 mm extension in line.

N·m
mm
mm

Result

80.0N·mWrench setting

Set the wrench to 80.0 N·m for 100.0 N·m

  • Caution : Valid only for an extension in line with the wrench.
Attach this calculation to a work order

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The wrench setting kept in the procedure

Here, the calculator is free and the result is gone when you close the page. In Reglova, it is attached to the work order on the right machine: you find it again at the next breakdown, and on audit day.

The CMMS software comparison, our gaps included
  • Attached to the work order with its inputs: the server recalculates it, it stays verifiable.
  • On the technician's phone, even without a network.
  • In the machine's history, for the next breakdown.
  • The result becomes a checklist step of the work order.
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Reglova · Calculations · Work order WO-AT01-04219
Silent video, 33 s: from the work order for an oil leak on a shear cylinder, the tightening torque of an M12 bolt, then "Attach to the work order". A step to tighten it to 93.1 N·m lands in the checklist (step text from the French demo data). Watch the video

When a crowfoot or extension changes the torque

  1. 01

    Tighten a hard-to-reach nut with a crowfoot or an offset adapter.

  2. 02

    Avoid over-tightening that stretches a bolt or damages a thread.

  3. 03

    Record the setting in the procedure so the next technician tightens the same way.

Good to know

The formula applies to an extension in line with the wrench. Turned at 90°, the extension does not change the lever arm; turned back towards the handle, it shortens it (enter a negative length).

Torque wrench extension formula: T·L/(L + E)

An extension in line with the wrench lengthens the lever arm: the torque actually applied exceeds the set value. The calculator gives the setting to use from the required torque, the wrench length (from the square drive axis to the handle's load mark) and the extension length.

Formula · Reference documents

T setting = T required · L / (L + E)

ISO 6789

Inputs and accepted ranges
InputUnitAccepted rangeExample
Required torqueN·m0.1 to 100,000100 N·m
Wrench length Lmm10 to 3,000400 mm
Extension Emm-2,000 to 2,000100 mm
Calculated results
  • Wrench settingN·m
What the calculator flags
  • Valid only for an extension in line with the wrench.
  • Extension pointing back to the handle: check the set-up.

Tightening procedures every technician follows the same way

  • Breakdowns reported by QR code
  • Work orders on the phone, even without a network
  • Mandatory inspections reminded by email
  • Audit file as a PDF, in one click
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Free during the beta, no credit card