By Zencalcy Editorial TeamLast reviewed About us
Strain measures the relative deformation of a material. Engineering strain is the change in length divided by the original length.
Deformation per unit length.
ε = ΔL / L₀
ε is engineering strain, ΔL is the change in length and L₀ the original length. Positive values indicate elongation, negative values contraction.
| Symbol | Meaning |
|---|---|
| ε | Engineering strain. |
| ΔL | Change in length. |
| L₀ | Original length. |
ε = ΔL / L₀ = 2 mm / 100 mm = 0.02, i.e. 2 % elongation.
Continue with the Young's Modulus Calculator, Shear Modulus Calculator, or the Bulk Modulus Calculator — or browse more materials and elasticity tools and all physics calculators.
Engineering strain uses the original length as the denominator. True strain accumulates the incremental strain and is the natural logarithm of the ratio of final to original length.
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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Content updated: September 2026