Calculate how much a material lengthens or expands when heated, from its initial length or volume, expansion coefficient and temperature change.
Last updated: November 8, 2026
Linear and volume expansion
Solids expand as they warm up. How much depends on the original size, the material's coefficient and the temperature change: • Linear: ΔL = α × L₀ × ΔT • Volume: ΔV = β × V₀ × ΔT, with β ≈ 3α for solids • α is usually given in 10⁻⁶/K Example: a 10 m steel rail (α = 12 × 10⁻⁶/K) warming by 40 °C grows by 12 × 10⁻⁶ × 10 × 40 = 0.0048 m, or 4.8 mm. Approximate α values (10⁻⁶/K): steel 12, concrete 12, glass 9, copper 17, brass 19, aluminium 23. Cooling shrinks it by the same amount. Liquids don't follow the 3α rule; use their own β.
Common questions about thermal expansion
ΔL = α × L₀ × ΔT, where α is the expansion coefficient, L₀ the original length and ΔT the temperature change.
Other tools you may find useful
In metres.
Steel 12, aluminium 23, copper 17, glass 9.
Kelvin = °C difference.