Machine design tool · V0.8

Factor of Safety Screening Calculator

Use a simple strength-to-stress ratio as a transparent screening calculation, then verify the actual governing failure mode.

Applied equivalent stress (MPa)

Selected limiting strength (MPa)Choose the relevant limit for the failure mode being screened.

Required factor of safety

Calculated FoS—

Allowable stress at required FoS—

Utilization vs allowable—

Margin to required FoS—

Select a strength that matches the failure mode.

n = strength / applied stress · σallow = strength / nrequired

A single scalar factor of safety is not a complete failure analysis. Yield, ultimate rupture, fatigue, buckling, fracture, creep, wear, contact stress and uncertainty can require different criteria and separate margins.