Stretch a rubber band and it gets thinner. Poisson’s ratio measures this sideways contraction: about 0.3 for metals, nearly 0.5 for rubber and close to 0 for cork – which is why cork makes such a good bottle stopper.
How to use the Poisson’s Ratio Calculator
- Method
- Lateral strain ε_lat
- Axial strain ε_axial
- Young’s modulus E
- Shear modulus G
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Choose the method. Enter strains as fractions (or percent consistently) – a lateral contraction is negative.
Inputs explained
| Field | What to enter |
|---|---|
| Method | Choose one: From strains, From E and G |
| Lateral strain ε_lat | A number |
| Axial strain ε_axial | A number |
| Young’s modulus E | Units: GPa, MPa, Pa, psi, Mpsi |
| Shear modulus G | Units: GPa, MPa, Pa, psi, Mpsi |
Example values
How the main result changes when Lateral strain ε_lat changes and everything else stays at the example values above:
| Lateral strain ε_lat | Poisson’s ratio ν |
|---|---|
| -0.0003 | 0.15 |
| -0.0005 | 0.225 |
| -0.0006 | 0.3 |
| -0.0007 | 0.375 |
| -0.0009 | 0.45 |
| -0.0012 | 0.6 |
Formula
ν = −ε_lateral / ε_axial = E/(2G) − 1
Worked example
Inputs — Method: From strains; Lateral strain ε_lat: -0.0006; Axial strain ε_axial: 0.002.
Results — Poisson's ratio ν = 0.3; Typical of = Metals.
Key terms
- Strain
- Relative deformation, ΔL/L.
Frequently asked questions
What is Poisson's ratio of steel?
About 0.27–0.30.
Can Poisson's ratio be negative?
Yes – auxetic materials get fatter when stretched.
Why is 0.5 the upper limit?
It corresponds to incompressible materials.
Why is cork used for stoppers?
Its ν ≈ 0 means it doesn't bulge when pushed in.