Bridges, rails and pipelines need expansion joints because materials grow when heated.
How to use the Thermal Expansion Calculator
- Material
- Original length
- Temperature change
Results update as you type, and every field accepts the units shown in its menu.
How it works
Multiply the original length by the expansion coefficient and the temperature change.
Inputs explained
| Field | What to enter |
|---|---|
| Material | Choose one: Steel (12×10⁻⁶ /K), Aluminium (23×10⁻⁶), Copper (17×10⁻⁶), Concrete (12×10⁻⁶) … |
| Original length | Units: m, cm, mm, km, in, ft … |
| Temperature change | In °C (K) |
What each result means
- Change in length = [Material] × [Original length] × [Temperature change]
- New length = [Original length] + [Change in length]
Example values
How the main result changes when Original length changes and everything else stays at the example values above:
| Original length (m) | Change in length (mm) |
|---|---|
| 50 | 24 |
| 75 | 36 |
| 100 | 48 |
| 125 | 60 |
| 150 | 72 |
| 200 | 96 |
Formula
ΔL = α × L₀ × ΔTWorked example
Inputs — Material: Steel (12×10⁻⁶ /K); Original length: 100 m; Temperature change: 40 °C (K).
Results — Change in length = 48 mm; New length = 100.048 m.
Frequently asked questions
Why are there gaps in bridges?
To let the deck expand and contract without cracking.
What about volume expansion?
For solids, the volume coefficient is about 3α.
What formula does the Thermal Expansion Calculator use?
ΔL = α × L₀ × ΔT.