Thermal Expansion Calculator
Find the linear dimensional change of a part from its original length, material coefficient of thermal expansion, and temperature change.
Enter your values
Original length, material, and temperature change.
How this calculator works
For a temperature change well within a material's normal operating range, linear thermal expansion is approximately proportional to the original length, the temperature change, and the material's coefficient of linear expansion:
L₀ is the original length, α is the coefficient of linear thermal expansion, and ΔT is the temperature change (positive for heating, negative for cooling — a negative ΔT gives a negative, i.e. contracting, ΔL).
Typical coefficients of linear expansion
| Material | α (×10⁻⁶ /°C) |
|---|---|
| Mild / carbon steel | ~12 |
| Stainless steel (304) | ~17.3 |
| Aluminum | ~23.1 |
| Copper | ~16.6 |
| Brass | ~19.1 |
| Cast iron | ~11.7 |
These are typical reference values at room temperature — α itself varies somewhat with temperature, so for large temperature swings check the material datasheet for a temperature-specific value.
Frequently asked questions
Does this account for constrained expansion (thermal stress)?
No — this calculates free, unconstrained expansion. A part that is rigidly restrained from expanding will instead develop internal thermal stress, which requires a separate stress calculation using the material's modulus of elasticity.
Can I use this for area or volume expansion?
This calculator covers linear (one-dimensional) expansion only. Area expansion is approximately 2α·ΔT and volumetric expansion is approximately 3α·ΔT, for the same material and temperature change.