# Thermal Expansion Calculator

URL: https://speedycalculator.com/calculators/physics/thermal-expansion/
Last updated: 2026-10-25

> The thermal expansion calculator finds how much a solid lengthens when heated, ΔL = α L ΔT. Choose steel, aluminium, concrete, glass or enter your own coefficient.

## Inputs

- Material
- Original length (m, cm, mm, km, in, ft, yd, mi)
- Temperature change (°C (K))

## Results

- Change in length
- New length

## Formula

```
ΔL = α × L₀ × ΔT
```

## Explanation

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

FieldWhat to enterMaterialChoose one: Steel (12×10⁻⁶ /K), Aluminium (23×10⁻⁶), Copper (17×10⁻⁶), Concrete (12×10⁻⁶) …Original lengthUnits: m, cm, mm, km, in, ft …Temperature changeIn °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)5024753610048125601507220096

## Worked 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.

## FAQ

**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.