How this calculator works
Use opposite strain signs for ordinary uniaxial tension: axial extension is positive and lateral contraction is negative. The moduli relation applies to isotropic, linear 3D elasticity. The stability range excludes its limiting endpoints; a ratio approaching 0.5 describes near incompressibility.
Formula
nu = -epsilon_transverse/epsilon_axial; E = 2G(1 + nu).
Worked example
A lateral strain of -0.0006 with axial strain 0.002 gives nu = 0.3. E = 210 GPa and G = 84 GPa give nu = 0.25.
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Frequently asked questions
Can Poisson's ratio be negative?
Yes. Auxetic materials expand laterally under uniaxial tension and have a negative ratio.
Can I use positive strain magnitudes?
The strain method needs signed values. Using two positive magnitudes would incorrectly produce a negative ratio.
Does the range apply to every material?
The stated range is for stable isotropic 3D linear elasticity. Directional ratios in anisotropic materials have different constraints.