Calculates how much a material’s length changes as its temperature rises or falls.
How it works
The original length is multiplied by the material’s linear expansion coefficient and by the temperature change.
What this does not include
This calculates linear (one-dimensional) expansion — area and volume expansion follow related but different formulas this calculator doesn’t cover directly.
How to use this calculator
- Enter the original length, the material’s expansion coefficient, and the temperature change.
A worked example
A 10 m rod with expansion coefficient 0.000012 per °C, heated 50°C: expansion = 10 × 0.000012 × 50 = 0.006 m (6 mm).
A 100 m rod, coefficient 0.0000235, heated 20°C: expansion = 0.047 m.
What the variables mean
| Variable | Meaning |
|---|---|
| Length | Original length of the material |
| Coefficient | Linear expansion coefficient, specific to the material |
| ΔT | Temperature change, in degrees |
Edge cases worth knowing
Different materials expand at very different rates — the expansion coefficient must match the actual material (steel, aluminum, concrete each differ), since using the wrong one gives a misleading result.
A negative ΔT (cooling) produces contraction, not expansion — a negative result is a valid, physically meaningful outcome, not an error.
Frequently asked questions
Why do bridges have expansion joints?
Metal and concrete expand and contract with temperature swings, and expansion joints give structures room to move without cracking or buckling.
Why does the expansion coefficient differ by material?
It reflects how strongly a material’s atomic bonds respond to temperature change — some materials (like most metals) expand more readily than others (like some ceramics or invar alloys, engineered to expand very little).
Does a negative temperature change give a negative expansion?
Yes — cooling produces contraction (a negative length change), which this same formula correctly handles by simply reversing the sign.
