Factor of Safety Calculator

ENGINEERING PRINCIPLE

Factor of safety compares a stated limiting strength with the applied stress.

Calculate a simple factor of safety from allowable strength and applied stress.

FORMULA & VARIABLES

n = allowable strength / applied stress

• n = factor of safety
• allowable strength = selected design limit
• applied stress = calculated or measured stress

CALCULATION STEPS

How this result is assembled

1. Convert the entered values to the SI basis required by the formula.
2. Apply n = allowable strength / applied stress using the current inputs.
3. Present the result as 2.5 — and review the stated assumptions.

FORMULA VERIFICATION

Units, scope and reference

Reference: NIST SP 811 for unit relationships; standard classical mechanics and strength-of-materials derivations for the stated scalar relation.

Internal basis: All inputs are converted to the calculator’s SI base before the formula is evaluated.

Valid conditions: Positive finite scalar input values in the current calculator model.

Limitations: The allowable strength must be selected for the material, loading and applicable standard. This simple ratio is not a complete failure or code-compliance assessment.

ASSUMPTIONS

Use this result in context

• The allowable strength must be selected for the material, loading and applicable standard.
• This simple ratio is not a complete failure or code-compliance assessment.

Results must be verified by a qualified engineer and checked against applicable engineering standards, material properties, loading conditions and design requirements.

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