How this calculator works
Choose a force or stress basis. Use a limiting strength appropriate to the failure mode and compare it with working stress on the same basis. Yield strength is common for ductile static yielding; ultimate strength addresses a different limit. The result is a nominal ratio. Loads, resistance factors, fatigue, buckling and the applicable design standard still need separate treatment.
Formula
n = limiting strength / working stress; allowable stress = limiting strength / n.
Worked example
A 300 MPa limiting strength and 100 MPa demand give a safety factor of 3. With a target factor of 2.5, the allowable stress is 120 MPa.
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Frequently asked questions
Can I compare two forces instead?
Yes. Choose the force basis to compare a limiting load with a working load in consistent force units.
Does a value above one certify safety?
It only indicates that the chosen nominal demand is below the chosen capacity. It does not check other failure modes or code requirements.
Which strength should I choose?
Choose the strength that matches the governing failure mechanism, material condition and design method.