↗Torque Extension

Crowfoot tools

Crowfoot torque calculator for angled extensions.

Find the wrench setting that delivers the specified fastener torque when a crowfoot changes the effective lever arm.

First, identify the tool

Select a card to see its rule

What kind of extension are you using?

Live calculator

See the correction as you turn the angle.

Measure from drive centre to grip centre for L, and drive centre to fastener centre for E. Keep both in the same length unit.

Live force diagram0° extension angle

The orange line is the full effective arm from the grip to the fastener projected onto the handle axis: L + E cos θ. E is drawn along the extension itself.

Torque required at the fastener, or the value currently set on the wrench.
Square-drive centre to hand-grip centre.
mm
Drive centre to fastener centre.
0° inline90° no correction180° reversed
Optional: check a wrench range
N·m
Set your wrench toFORWARD
78.18N·m

That setting delivers 86.00 N·m at the fastener for this geometry.

−9.09% correctionEffective arm 275.00 mm

B · Click simulation

Feel the difference before you tighten.

Play the pull using the live calculator values. Both gauges use the same fastener-torque scale and the target mark never moves.

UncorrectedReady
0targetmax

Wrench set to —

Fastener gets —

CorrectedReady
0targetmax

Wrench set to —

Fastener gets —

Press play to see the needle rise and the click land.

C · Angle tour

The angle changes the projection, not the tool’s length.

Watch the correction factor move from maximum correction at 0° to reverse correction at 180°. 90° is the no-correction position.

Tool head rotates from 0° to 180°

factor = L / (L + E cos θ)1.00°45°90°135°180°extension angle θfactor1.0 · no correction
0° · factor 0.909

At 90°, cos θ is zero, so the extension contributes no projected length.

E · Measure it right

How to measure L and E.

Torque is force multiplied by perpendicular distance. Centre-to-centre measurements are the reliable ones.

L · centre to centredrive centregrip centre

L — wrench effective length

Start at the square-drive centre and end at the hand-grip centre—the handle mark or groove where your palm applies force.

E · centre to centredrive centrejaw centre

E — extension length

Measure from the square-drive centre to the fastener or jaw centre—not to the outer edge of the crowfoot.

✗ overall body lengthdo not measure end to end

Common trap: overall length

The body can extend beyond the working points. Use the drive and grip centres that define the actual torque arm.

Common mistakes

Small measurement mistakes create big torque errors.

Using overall length for L

End L at the hand-grip centre, where force is applied.

Mixing mm and inches

Convert both lengths to one unit before calculating.

Installing at 90°

A perpendicular crowfoot keeps the effective arm unchanged.

Crowfoot answers

Crowfoot calculator FAQ

What should I enter for E?

Measure from square-drive centre to fastener centre, not the outside of the crowfoot.

Does a 90° crowfoot need a correction?

No. At 90°, the extension has no projection along the wrench handle, so set the target torque.

What is the common inline example?

For 86 N·m, L 250 mm and E 25 mm at 0°, set 78.18 N·m.

Crowfoot example

86 N·m inline crowfoot example.

With L = 250 mm, E = 25 mm and θ = 0°, set the wrench to 78.18 N·m.