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True Strain Calculator.

Convert engineering strain to logarithmic true strain for a uniform uniaxial deformation.

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True strain: 0.182322

True strain

0.000000

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Use Cases

Material Testing and Analysis

Convert engineering strain data from tensile tests to true strain for accurate stress-strain curves, especially in the plastic deformation region.

Example: If a tensile test shows 50% elongation (engineering strain = 0.5), true strain = ln(1.5) ≈ 0.405.

Finite Element Modeling (FEM)

Use true strain values as input for material models in simulation software, which often require logarithmic strain for large-deformation analysis.

Example: For an engineering strain of 1.0 (100% elongation), true strain = ln(2) ≈ 0.693.

Frequently Asked Questions

What is true strain and how is it different from engineering strain?
True strain (also called logarithmic strain) measures deformation incrementally, accounting for the changing length of the specimen. Engineering strain is the change in length divided by the original length. For large deformations, true strain is more accurate.
How do I use this calculator?
Enter the engineering strain value (a dimensionless ratio, e.g., 0.2 for 20% elongation) into the input field. The calculator will compute the true strain using the formula: true strain = ln(1 + engineering strain).
Can I use this calculator for any material?
Yes, the conversion is purely mathematical and applies to any material undergoing uniform uniaxial deformation, as long as the engineering strain is greater than -1 (i.e., the material is not compressed to zero length).

Tips & Common Mistakes

Tips

  • Ensure the engineering strain is a dimensionless number (e.g., 0.1 for 10% elongation). If you have percent elongation, divide by 100 first.
  • True strain is always less than engineering strain for positive elongation, and greater for compression (negative engineering strain).
  • For small strains (e.g., < 0.1), true strain and engineering strain are nearly equal, so the conversion is less critical.
  • This calculator assumes uniform uniaxial deformation; for non-uniform deformation, true strain may not be accurately represented by this simple formula.

Common Mistakes to Avoid

  • Entering percent elongation directly (e.g., 50 instead of 0.5) without converting to a decimal fraction.
  • Using engineering strain values less than -1, which would imply a negative length and are physically impossible.
  • Confusing true strain with true stress or other strain measures; this calculator only converts engineering strain to true strain.

Last updated: August 13, 2026