Materials

Thermal Expansion Calculator

Calculate material length and volume change with temperature.

Input Parameters

Units:

Material

Original Length

Initial Temperature

°F

Final Temperature

°F

Results

Enter material and temperatures, then click Calculate

What is Thermal Expansion?

Thermal expansion is the tendency of materials to change their dimensions in response to temperature changes. Most materials expand when heated and contract when cooled.

Understanding thermal expansion is critical for designing assemblies that operate across temperature ranges, selecting interference fits, and preventing thermal stress failures.

How to Use

Select the material from the dropdown (or enter custom coefficient)
Enter the original length of the part
Enter the initial temperature (reference condition)
Enter the final temperature (operating condition)
Click Calculate to see dimensional change

FAQs

The coefficient of thermal expansion (CTE or α) is a material property that describes how much a material's dimensions change per degree of temperature change. It's typically expressed in parts per million per degree (ppm/°F or ppm/°C). Higher coefficients mean more expansion.

Aluminum has weaker metallic bonds than steel, allowing atoms to move apart more easily when heated. Its CTE is about 2× that of carbon steel. This difference is important when combining materials - an aluminum part press-fit into steel will loosen when heated.

Invar (64% iron, 36% nickel) has an extremely low coefficient of thermal expansion - about 1/10th of steel. It's used in precision instruments, scientific equipment, and clock pendulums where dimensional stability over temperature is critical.

For constrained parts, use expansion joints, slotted holes, or flexible connections. For interference fits, calculate the temperature needed to expand/contract parts for assembly. For precision assemblies, match material CTEs or use compensating designs.

Yes - both diameter and pitch change with temperature. If materials are mismatched, threads can tighten or loosen. Stainless bolts in aluminum can gall when heated due to aluminum's greater expansion. Use anti-seize compounds and appropriate torque values.

Limitations

• Assumes constant coefficient over temperature range
• CTE varies with alloy composition and heat treatment
• Does not calculate thermal stress in constrained parts
• Linear expansion only - use separate calculations for area/volume
• Verify specific alloy data from material supplier