By Zencalcy Editorial TeamLast reviewed About us
Engineering stress and strain are the most common forms used in introductory mechanics. Engineering stress uses the original area; engineering strain uses the original gauge length.
Engineering stress, strain and tangent modulus.
σ = F / A₀, ε = ΔL / L₀, E_t = σ / ε
σ is engineering stress, ε engineering strain, E_t the tangent modulus (also called secant modulus). A₀ the original area, F the axial force, ΔL the change in length and L₀ the original gauge length.
| Symbol | Meaning |
|---|---|
| σ | Engineering stress. |
| ε | Engineering strain. |
| E_t | Tangent (secant) modulus. |
| F | Axial force. |
| A₀ | Original cross‑sectional area. |
| ΔL | Change in length. |
| L₀ | Original gauge length. |
σ = 50 000 N / 2×10⁻⁴ m² = 250 MPa; ε = 0.01 / 0.05 = 0.20; E_t = 250 MPa / 0.20 = 1.25 GPa.
Continue with the True Stress Calculator, True Strain Calculator, or the Bearing Stress Calculator — or browse more materials and elasticity tools and all physics calculators.
Engineering stress uses the original area; true stress uses the instantaneous (reduced) area. True stress is higher during drawing.
Results are computed from the standard equations of classical mechanics. Unit conversions use the SI definitions published by NIST. Air resistance is ignored unless the calculator names a drag model.
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Last reviewed: September 2026. See how we build and check every tool on the about page.
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Content updated: September 2026