What is the Strain Calculator?
Calculate engineering strain with this free strain calculator. Find axial strain ε = ΔL/L₀, shear strain γ = δ/h, elastic strain from Hooke's law ε = σ/E, thermal strain ε = αΔT, and lateral Poisson strain ε_lat = −ν·ε_axial. Results in dimensionless strain, microstrain (με), and percent. Metric and imperial units with material presets for E, α, and ν. Runs instantly in your browser.
How to use the Strain Calculator
- Choose axial, shear, Hooke's law, thermal, or Poisson strain mode.
- Select metric or imperial units.
- Enter deformation dimensions, stress and modulus, thermal α and ΔT, or axial strain and ν.
- Optionally enter original length for thermal ΔL or lateral dimension for width change.
- Review ε, microstrain, percent strain, and calculation steps.
Common use cases
- Converting tensile test elongation to engineering strain
- Elastic strain from known stress and steel modulus
- Thermal expansion strain for a bridge or rail temperature swing
- Lateral contraction from axial load using Poisson's ratio
- Materials homework on ε, γ, and Hooke's law
Frequently asked questions
- What is engineering strain?
- Engineering (Cauchy) strain ε = ΔL/L₀ is the change in length divided by the original length. It is dimensionless; multiply by 10⁶ for microstrain (με) as used on strain gauges.
- How does Hooke's law relate stress and strain?
- In the elastic range, ε = σ/E where E is Young's modulus. Doubling stress doubles strain until the proportional limit is exceeded.
- What is thermal strain?
- Materials expand when heated: ε_thermal = α × ΔT, where α is the coefficient of thermal expansion. Enter α in ×10⁻⁶ per °C or °F to match your temperature units.
- What is Poisson's ratio?
- When a bar stretches axially, it usually contracts laterally. Poisson's ratio ν links them: ε_lateral = −ν × ε_axial. Steel is about 0.3; rubber approaches 0.5.
- What is microstrain?
- Microstrain με = ε × 10⁶. A strain of 0.001 equals 1000 με — a typical value for structural steel near yield.
