Calculate how materials change size with temperature using linear, area, and volume expansion formulas. Compare materials and analyze gap changes in multi-material assemblies.
Enter coefficient in 10⁻⁶/°C units (e.g., 12 for carbon steel)
Enter material properties, initial dimensions, and temperature change to calculate how much an object will expand or contract.
Thermal expansion is the tendency of matter to change in shape, area, volume, and density in response to a change in temperature. When most materials are heated, their molecules vibrate more vigorously, causing them to take up more space. This phenomenon is fundamental to mechanical engineering, materials science, and structural design.
For one-dimensional expansion (length change):
Where ΔL is the change in length, αL is the linear coefficient of thermal expansion (1/°C), L₀ is the initial length, and ΔT is the temperature change.
For two-dimensional expansion (surface area change):
For three-dimensional expansion:
| Material | αL (×10⁻⁶/°C) | Notes |
|---|---|---|
| Carbon Steel | ~12 | Common structural steel |
| Stainless Steel | ~17 | 304/316 grades |
| Aluminum | ~23 | High expansion rate |
| Copper | ~17 | Good conductor |
| Invar | ~1.2 | Low-expansion alloy |
| Glass | ~8 | Soda-lime glass |
| Polyethylene | ~200 | Plastics expand much more |
When two parts made of different materials are assembled with a gap between them, temperature changes cause each part to expand or contract at different rates. The gap between them changes accordingly:
This calculator assumes small-strain conditions (ΔL ≪ L₀), uniform temperature throughout the object, isotropic materials, and constant coefficient of thermal expansion. It computes only geometric changes—not thermal stresses from constrained expansion. For safety-critical structural design, consult qualified engineers.
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