Thermal Expansion Calculator

Calculate how much a material expands or contracts with temperature change.

Coefficient of thermal expansion shown in parentheses (×10⁻⁶ /°C)

mm
°

Positive for heating, negative for cooling

Change in Length (ΔL)

—

ΔL = α × L₀ × ΔT

Final Length

—

L₀ + ΔL

Percentage Change

—

(ΔL / L₀) × 100

Material Info

Select a material to see its thermal expansion coefficient.

Thermal Expansion Guide

Linear Expansion Formula

The change in length due to temperature change is:

\u0394L = \u03B1 \u00D7 L\u2080 \u00D7 \u0394T

  • \u0394L = change in length
  • \u03B1 = coefficient of linear thermal expansion
  • L\u2080 = original length
  • \u0394T = change in temperature

Real-World Examples

  • Bridges: A 100m steel bridge expanding 50\u00B0C grows about 60mm (2.4 inches). Expansion joints absorb this movement
  • Railroad tracks: Continuous welded rail is pre-stressed to handle expansion. In extreme heat, improperly maintained track can buckle
  • Pipes: Steam pipes use expansion loops or bellows to absorb thermal growth without creating stress
  • Glass: Borosilicate glass (Pyrex) has a low CTE, making it resistant to thermal shock compared to regular soda-lime glass
  • Bimetallic strips: Two bonded metals with different CTEs bend when heated, used in thermostats and circuit breakers

Material Comparison

Material CTE (\u00D710\u207B\u2076 /\u00B0C)
Lead29.0 (highest)
Aluminum23.1
Brass19.0
Copper16.5
Steel12.0
Titanium8.6
Glass8.5 (lowest)

Volumetric Expansion

For three-dimensional expansion, the volumetric coefficient is approximately 3 times the linear coefficient:

\u0394V \u2248 3\u03B1 \u00D7 V\u2080 \u00D7 \u0394T

This approximation is valid for small temperature changes. For liquids and gases, volumetric expansion is the primary concern.

Note: CTE values are averages for typical temperature ranges. Actual values may vary with specific alloy composition and temperature range.

Frequently Asked Questions

What is thermal expansion?
Thermal expansion is the tendency of materials to change in volume or length in response to temperature changes. When materials are heated, their atoms vibrate more energetically and push apart, causing the material to expand. When cooled, the material contracts. This behavior is predictable and characterized by the coefficient of thermal expansion (CTE), which is unique to each material.
What is the coefficient of thermal expansion?
The coefficient of thermal expansion (CTE or α) is a material property that quantifies how much a material expands per degree of temperature change. It is expressed in units of per degree Celsius (µm/m/°C or simply 10⁻⁶ /°C). A higher CTE means the material expands more for the same temperature change. Aluminum has a high CTE (23.1) while glass has a low CTE (8.5).
Why does thermal expansion matter in engineering?
Thermal expansion must be accounted for in any structure or system that experiences temperature changes. Bridges use expansion joints to prevent buckling. Railroad tracks can buckle in extreme heat if not properly designed. Pipes need expansion loops. Dissimilar metals bonded together can warp (bimetallic strip effect). Failure to account for thermal expansion can cause structural failure, leaks, and equipment damage.
What is the difference between linear and volumetric expansion?
Linear thermal expansion describes how a single dimension (length) changes with temperature: ΔL = α × L₀ × ΔT. Volumetric expansion describes how the total volume changes and uses a coefficient approximately 3 times the linear coefficient: ΔV ≈ 3α × V₀ × ΔT. This calculator focuses on linear expansion, which is most commonly needed for structural and mechanical calculations.

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