Poisson's Ratio Calculator

About this calculator

Poisson's ratio (ν, nu), named after French mathematician Siméon Poisson, quantifies how much a material contracts in directions perpendicular to an applied load: it is defined as the negative ratio of transverse (lateral) strain to axial (longitudinal) strain during uniaxial tension or compression. Most engineering metals have a Poisson's ratio near 0.3, incompressible materials like rubber approach the theoretical upper limit of 0.5, and cork is famously close to 0, which is why it can be pushed into a bottle without bulging sideways.

Mechanical, civil, and materials engineers use Poisson's ratio alongside Young's modulus and shear modulus to fully characterize a material's elastic behavior in stress analysis, finite element modeling, and structural design — it directly affects calculations like stress concentration around holes, buckling behavior, and how pressurized pipes or vessels deform.

This calculator takes your measured lateral and axial strain from a tensile or compressive test and computes the resulting Poisson's ratio.