# Poisson’s Ratio Calculator

URL: https://speedycalculator.com/calculators/physics/poissons-ratio/
Last updated: 2026-10-30

> The Poisson's ratio calculator finds a material's Poisson's ratio from its lateral and axial strains, or from its Young's and shear moduli.

## Inputs

- Method
- Lateral strain ε_lat
- Axial strain ε_axial
- Young's modulus E (GPa, MPa, Pa, psi, Mpsi)
- Shear modulus G (GPa, MPa, Pa, psi, Mpsi)

## Results

- Poisson's ratio ν
- Typical of

## Formula

```
ν = −ε_lateral / ε_axial = E/(2G) − 1
```

## Explanation

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

FieldWhat to enterMethodChoose one: From strains, From E and GLateral strain ε_latA numberAxial strain ε_axialA numberYoung's modulus EUnits: GPa, MPa, Pa, psi, MpsiShear modulus GUnits: 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_latPoisson's ratio ν-0.00030.15-0.00050.225-0.00060.3-0.00070.375-0.00090.45-0.00120.6

## 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.

## FAQ

**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.


## Sources

- [MIT OpenCourseWare – Mechanics of Materials](https://ocw.mit.edu/courses/2-001-mechanics-materials-i-fall-2006/)
- [The Engineering ToolBox](https://www.engineeringtoolbox.com/)