Thermal Expansion Calculator

Most materials expand when heated and contract when cooled. Expansion joints on bridges, gaps in railway tracks, and bimetallic thermostat strips all exploit or accommodate this behavior. Ignore thermal expansion in precision assemblies and parts bind or crack — a steel bridge span lengthens centimeters between winter and summer extremes.

Linear thermal expansion:

ΔL = α × L₀ × ΔT

Where ΔL is length change, α is linear expansion coefficient in 1/K (or 1/°C), L₀ is original length, and ΔT is temperature change. Final length L = L₀ + ΔL. Volume expansion for isotropic solids: ΔV/V ≈ 3αΔT when α is small. Area expansion uses ΔA/A ≈ 2αΔT.

Select material for tabulated α or enter custom coefficient. Aluminum expands more than steel (α ≈ 23 × 10⁻⁶ /K vs 12 × 10⁻⁶ /K). A 50 m steel bridge rail at ΔT = 40 K grows ΔL = 12×10⁻⁶ × 50 × 40 = 0.024 m = 2.4 cm — expansion joints must absorb this without buckling.

Worked example: A brass rod L₀ = 2.00 m, α = 19 × 10⁻⁶ /K, heated from 15°C to 95°C (ΔT = 80 K). ΔL = 19×10⁻⁶ × 2.00 × 80 = 0.00304 m = 3.04 mm. In a constrained slot with zero clearance, that 3 mm produces enormous stress — engineers design slip joints or choose low-α materials like Invar for optical benches.

Combine with specific heat when both temperature and dimension change matter, and celsius-to-kelvin for absolute temperature references. Pipe designers pair expansion calculations with pressure analysis for hot fluid lines.