True Strain Calculator

How to use this calculator

1. Choose whether to find true strain, engineering strain, or the natural log ratio.
2. Enter the two known values; the material should have undergone significant deformation.
3. Read the result; true strain is larger in magnitude than engineering strain for the same deformation.

Formula

εₜ = ln(1 + ε)

ε is the engineering strain and εₜ the true (logarithmic) strain. True strain is positive for elongation and negative for compression.

Worked example

Example: ε = 0.2 → εₜ = ln(1.2) ≈ 0.1823

εₜ = ln(1 + ε) = ln(1.2) = 0.1823, i.e. 18.23 % true strain.

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