Physics

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Poisson's Ratio Calculator.

Calculate Poisson's ratio from signed axial and lateral strains.

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Poisson's ratio: 0.3

Poisson's ratio

0.300000

Results update automatically as you type.

Use Cases

Material property analysis

Determine Poisson's ratio for a material from experimental strain measurements, helping to characterize its mechanical behavior.

Example: If lateral strain is -0.0003 and axial strain is 0.001, Poisson's ratio is 0.3.

Engineering design validation

Verify that a material's Poisson's ratio falls within expected ranges for structural or mechanical design calculations.

Example: Check if a polymer has a Poisson's ratio near 0.4 for a flexible component.

Frequently Asked Questions

What is Poisson's ratio?
Poisson's ratio (ν) is a material property that describes how much a material deforms in the lateral direction relative to the axial direction when stretched or compressed. It is the negative ratio of lateral strain to axial strain.
How do I use this calculator?
Enter the lateral strain and axial strain values in the provided fields. The calculator will compute Poisson's ratio using the formula ν = -lateral strain / axial strain. Ensure the strains are signed (positive for elongation, negative for compression).
What are typical values of Poisson's ratio?
Most materials have Poisson's ratio between 0 and 0.5. For example, cork is near 0, rubber is close to 0.5, and metals like steel are around 0.3. Negative values are rare but possible in auxetic materials.

Tips & Common Mistakes

Tips

  • Ensure both strain values are in the same units (e.g., both as dimensionless ratios or both in percent) to get a correct ratio.
  • Use signed strains: positive for elongation, negative for compression. The calculator handles the sign automatically.
  • For accurate results, measure strains under small deformations within the elastic limit of the material.
  • Double-check that the lateral strain is perpendicular to the axial strain direction.

Common Mistakes to Avoid

  • Forgetting to include the negative sign in the formula, leading to a positive ratio instead of the correct negative ratio.
  • Entering strain values in different units (e.g., one in percent and the other as a decimal) without converting.
  • Using absolute values instead of signed strains, which can give incorrect results for compressive loading.

Last updated: August 13, 2026