Shaft Size Calculator

Find the minimum solid shaft diameter for a torque.

Minimum diameter 39.929

Formula: d = (16·T ÷ (π·τ))^(1/3)

Step-by-step with your numbers:

1. Values used:

2. Torque = 500 N·m

3. Allowable shear stress = 40 MPa

5. Minimum diameter = 39.929

Did we solve your problem today?

Size a transmission shaft so its shear stress stays within a safe limit.

The math behind it

From τ = 16T/(πd³), solve d = (16T ÷ (πτ))^(1/3).

500 N·m at 40 MPa allowable → about 40 mm.

Why cube root?

Torsional capacity scales with d³, so diameter changes slowly with torque.