Thermal Expansion Calculator
A free, browser-based calculator. Runs entirely in your browser — no sign up, nothing stored.
Enter Values
How to use this calculator
- Enter the original length L in metres.
- Enter the material's expansion coefficient α (in ×10⁻⁶ per °C) and the temperature change ΔT (negative for cooling).
- Read the change in length and the final length.
How it works
The Thermal Expansion Calculator uses linear expansion: ΔL = α · L · ΔT.
α is the coefficient of linear thermal expansion (steel ≈ 12, aluminium ≈ 23, concrete ≈ 10, copper ≈ 17, all ×10⁻⁶/°C). A positive temperature change lengthens the part; a negative one shortens it.
Worked example
10 m steel beam, +40 °C. ΔL = 12×10⁻⁶ × 10 × 40 = 0.0048 m = 4.8 mm of growth — why long steel runs need expansion joints.
Tips
- Coefficients are given per °C; a change in kelvin is numerically the same.
Frequently asked questions
What if the part can't expand freely?
If movement is restrained, the would-be expansion turns into thermal stress (σ ≈ α·E·ΔT). That can be large — for steel a 40 °C rise restrained fully is about 96 MPa — so allow for movement or design for the stress.
Can I use these results for final design?
No. These calculators are for first-pass sizing, checking and learning. They assume ideal supports, static loads and elastic behaviour, and they don't apply load factors, member capacity, buckling or connection checks. Always verify against the relevant design code (e.g. AS 4100, AS 1170, Eurocode) and have a qualified engineer sign off structural work.
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Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.