Linear Thermal Expansion Calculator

Most solid materials expand when heated and contract when cooled, and over the temperature ranges people actually encounter, that change is accurately linear: ΔL = α × L₀ × ΔT. L₀ is the original length, ΔT is the temperature change, and α (alpha) is the material's coefficient of linear expansion — how much each unit of length grows per degree. Steel is roughly 0.000012 per °C and aluminum roughly 0.000023 per °C; you supply the figure for your specific material (from a datasheet or reference table), since it's a looked-up material property rather than something this calculator can compute.

The temperature change converts cleanly between a Celsius-degree and Fahrenheit-degree magnitude using the page's unit toggle (a 1°C change equals 1.8°F of change — there's no zero-point offset to worry about, unlike converting an absolute temperature reading). The expansion coefficient itself stays fixed in "per °C" either way, the same way a spring constant or specific heat capacity on this site stays in one published unit rather than being rescaled.

This is the standard small-change approximation used throughout engineering (bridge expansion joints, railway track gaps, and pipe fitting all rely on it) — it assumes α itself doesn't vary over the temperature range in question, which holds well for the moderate swings most everyday and structural applications involve.