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Factor of Safety Calculator

Compare stress demand with yield strength or allowable stress using selected criteria.

Factor of Safety inputs

Result section

warningPlane stress closed-form solution

Preliminary factor of safety

2.46332

Secondary results

Von Mises stress: 101.489 MPa
Tresca equivalent stress: 112.426 MPa
Maximum shear stress: 56.2132 MPa
Preliminary factor of safety: 2.46332
Utilization ratio: 0.405956
Principal stress sigma 1: 112.426 MPa
Principal stress sigma 2: 27.5736 MPa
Principal stress sigma 3: 0 MPa

Unit conversion summary

Unit-normalization summary: 1.01489e+8 Pa; 1.12426e+8 Pa; 2.50000e+8 Pa

Warnings

Calculations are performed locally in your browser and are not submitted to a third-party calculation API.
Positive normal stress is tension. Negative normal stress is compression. Positive shear follows the displayed stress-element convention.
Do not label a design safe from this value alone; verify against standards and qualified engineering judgment.

Assumptions

Yield comparison is preliminary and uses the entered strength only.
Stress concentrations, fatigue, material standards, temperature, and load combinations are not evaluated.

Calculation steps

Resolve stress statePlane stress closed-form solution
Calculate principal stresses1.12426e+8 Pa, 2.75736e+7 Pa, 0 Pa
Calculate Von Mises1.01489e+8 Pa
Calculate Tresca1.12426e+8 Pa
Compare with entered strength2.46332

Factor of safety

sigma_v = sqrt(0.5*((s1-s2)^2+(s2-s3)^2+(s3-s1)^2))

n = strength / calculated demand.

sigma_v = 1.01489e+8 Pa

sigma_Tresca = 1.12426e+8 Pa

n = 2.50000e+8 Pa / 1.01489e+8 Pa

Technical visual

Engineering interpretation

Factor of safety is a demand-to-strength comparison, not a certification of design adequacy.

What is the factor of safety calculator?

Use this calculator for transparent preliminary strength-to-demand comparisons after selecting the criterion that matches your material and design context.

How to use the factor of safety calculator

Select the mode that matches the stress, material, section, or thermal data you already have.
Enter values with units; the calculator normalizes inputs to SI internally.
Review the formulas, normalized values, assumptions, and warnings before transferring the result to another check.
Choose a criterion carefully and treat the result as a preliminary comparison, not as a design certification.

Input explanations

Plane stress uses sigma x, sigma y, and tau xy with sigma z, tau yz, and tau zx equal to zero.
Three-dimensional mode accepts a symmetric Cauchy stress tensor.
Principal-stress mode accepts already solved sigma 1, sigma 2, and sigma 3 values.
Positive normal stress is tension; negative normal stress is compression.
Von Mises mode compares yield strength with distortion-energy equivalent stress.
Tresca mode compares yield strength with maximum-shear equivalent stress.
Maximum-principal mode compares strength with the largest absolute principal stress.
Allowable-stress mode compares entered allowable stress with absolute maximum principal stress.

Notation

Formula notation
Symbol	Meaning	Unit
n	Factor of safety	dimensionless
U	Utilization ratio	dimensionless
demand	Selected calculated stress demand	Pa
strength	Entered strength or allowable stress	Pa

Worked examples

If demand is 100 MPa and yield strength is 250 MPa, factor of safety is 2.5.

If demand is zero, the mathematical factor is infinite, but that does not certify safety.

Allowable-stress mode compares the entered allowable stress with the maximum absolute principal stress.

Cross-tool workflow

The Factor of Safety Calculator resolves stress demand from Von Mises, Tresca, maximum principal, or allowable-stress mode and reports factor of safety and utilization.

Convert stress units Review principal stresses

Common mistakes

Mixing sign conventions from different FEA postprocessors without checking tensor orientation.
Using displayed nodal extrapolated stresses as if they were fully validated design stresses.
Treating a scalar equivalent stress as a replacement for standards-based design review.
Ignoring stress concentrations, fatigue, temperature effects, welds, bolts, or load combinations.

Limitations

This is not a design-code engine and does not select allowable values.
No partial safety factors, load combinations, fatigue, fracture, buckling, weld, bolt, bearing, or contact checks are included.
Material strength values must come from reliable standards or project-specific data.

References

Roark's Formulas: Young, Budynas, and Sadegh, Roark's Formulas for Stress and Strain.
Shigley's Mechanical Engineering Design: Budynas and Nisbett, Shigley's Mechanical Engineering Design, McGraw-Hill.
Mechanics of Materials: Hibbeler, Mechanics of Materials, Pearson.
Theory of Elasticity: Timoshenko and Goodier, Theory of Elasticity, McGraw-Hill.

What is factor of safety?

It is the ratio of strength or allowable stress to calculated demand for the selected criterion.

What does utilization mean?

Utilization is demand divided by strength; it is the inverse of factor of safety.

Which criterion should I use?

That depends on material, loading, failure mode, and governing design standard. The tool does not choose it for you.

Can factor of safety be infinite?

In the idealized calculation, zero demand gives infinite factor of safety, but that does not prove a design is safe.

Does this include design-code safety factors?

No. It only compares entered values and calculated stress demand.

Does this calculator prove that a part is safe?

No. It reports an educational preliminary stress or factor comparison. Real design decisions need applicable standards, validated models, material data, and engineering review.

Can these results replace commercial FEA software?

No. ScholarTool provides transparent hand-calculation support and postprocessing checks, not a replacement for validated FEA solvers.

Professional support from ScholarEase Consultancy Services LLP

Professional FEA, simulation setup, solid-mechanics calculations, technical documentation, and research support are available through the connected services website. These calculators remain free to use without purchasing services.

Visit ScholarEase

Engineering disclaimer

This tool is intended for educational, estimation, and preliminary solid-mechanics support. Always verify critical engineering calculations with applicable standards, validated software, material data, and qualified professional judgment.

Need Professional Support?

ScholarTool is powered by ScholarEase Consultancy Services LLP. Professional engineering, simulation, research, and technical documentation support is available through the connected services website.

Visit ScholarEase

Last reviewed: 2026-06-21

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Factor of Safety inputs

Result section

warningPlane stress closed-form solution

Preliminary factor of safety

2.46332

Secondary results

Von Mises stress: 101.489 MPa
Tresca equivalent stress: 112.426 MPa
Maximum shear stress: 56.2132 MPa
Preliminary factor of safety: 2.46332
Utilization ratio: 0.405956
Principal stress sigma 1: 112.426 MPa
Principal stress sigma 2: 27.5736 MPa
Principal stress sigma 3: 0 MPa

Unit conversion summary

Unit-normalization summary: 1.01489e+8 Pa; 1.12426e+8 Pa; 2.50000e+8 Pa

Warnings

Calculations are performed locally in your browser and are not submitted to a third-party calculation API.
Positive normal stress is tension. Negative normal stress is compression. Positive shear follows the displayed stress-element convention.
Do not label a design safe from this value alone; verify against standards and qualified engineering judgment.

Assumptions

Yield comparison is preliminary and uses the entered strength only.
Stress concentrations, fatigue, material standards, temperature, and load combinations are not evaluated.

Calculation steps

Resolve stress statePlane stress closed-form solution
Calculate principal stresses1.12426e+8 Pa, 2.75736e+7 Pa, 0 Pa
Calculate Von Mises1.01489e+8 Pa
Calculate Tresca1.12426e+8 Pa
Compare with entered strength2.46332

Factor of safety

sigma_v = sqrt(0.5*((s1-s2)^2+(s2-s3)^2+(s3-s1)^2))

n = strength / calculated demand.

sigma_v = 1.01489e+8 Pa

sigma_Tresca = 1.12426e+8 Pa

n = 2.50000e+8 Pa / 1.01489e+8 Pa

How to use the factor of safety calculator

Select the mode that matches the stress, material, section, or thermal data you already have.
Enter values with units; the calculator normalizes inputs to SI internally.
Review the formulas, normalized values, assumptions, and warnings before transferring the result to another check.
Choose a criterion carefully and treat the result as a preliminary comparison, not as a design certification.

Input explanations

Plane stress uses sigma x, sigma y, and tau xy with sigma z, tau yz, and tau zx equal to zero.
Three-dimensional mode accepts a symmetric Cauchy stress tensor.
Principal-stress mode accepts already solved sigma 1, sigma 2, and sigma 3 values.
Positive normal stress is tension; negative normal stress is compression.
Von Mises mode compares yield strength with distortion-energy equivalent stress.
Tresca mode compares yield strength with maximum-shear equivalent stress.
Maximum-principal mode compares strength with the largest absolute principal stress.
Allowable-stress mode compares entered allowable stress with absolute maximum principal stress.

Symbol

Meaning

Unit

Factor of safety

dimensionless

Utilization ratio

dimensionless

demand

Selected calculated stress demand

strength

Entered strength or allowable stress

Common mistakes

Mixing sign conventions from different FEA postprocessors without checking tensor orientation.

Using displayed nodal extrapolated stresses as if they were fully validated design stresses.

Treating a scalar equivalent stress as a replacement for standards-based design review.

Ignoring stress concentrations, fatigue, temperature effects, welds, bolts, or load combinations.

References

Roark's Formulas: Young, Budynas, and Sadegh, Roark's Formulas for Stress and Strain.

Shigley's Mechanical Engineering Design: Budynas and Nisbett, Shigley's Mechanical Engineering Design, McGraw-Hill.

Mechanics of Materials: Hibbeler, Mechanics of Materials, Pearson.

Theory of Elasticity: Timoshenko and Goodier, Theory of Elasticity, McGraw-Hill.

Factor of Safety inputs

Stress state

Material properties

Result section

Secondary results

Unit conversion summary

Warnings

Assumptions

Calculation steps

Factor of safety

Technical visual

Engineering interpretation

What is the factor of safety calculator?

How to use the factor of safety calculator

Input explanations

Notation

Worked examples

Cross-tool workflow

Common mistakes

Limitations

References

Related tools

Professional support from ScholarEase Consultancy Services LLP

Print summary

Engineering disclaimer

Need Professional Support?

Factor of Safety inputs

Stress state

Material properties

Result section

Secondary results

Unit conversion summary

Warnings

Assumptions

Calculation steps

Factor of safety

Technical visual

Engineering interpretation

What is the factor of safety calculator?

How to use the factor of safety calculator

Input explanations

Notation

Worked examples

Cross-tool workflow

Common mistakes

Limitations

References

Related tools

Professional support from ScholarEase Consultancy Services LLP

Print summary

Engineering disclaimer

Need Professional Support?