How the thermal expansion calculator works
Most materials grow when heated and shrink when cooled. Over normal temperature ranges the change in length is proportional to the original length and the temperature change.
α is the coefficient of linear thermal expansion. The values used here are typical figures per °F from engineering handbooks: carbon steel about 6.5 × 10⁻⁶, aluminum 12.8 × 10⁻⁶, copper 9.4 × 10⁻⁶ and PVC about 28 × 10⁻⁶, which is why plastic pipe needs expansion loops. To work in Celsius, multiply these coefficients by 1.8. A negative temperature change gives contraction.
Worked example
A 100 ft steel pipe that warms by 100 °F grows 6.5 × 10⁻⁶ × 100 × 100 = 0.065 ft, or 0.78 in (19.8 mm). The same length of PVC would grow 3.36 in, more than four times as much, and aluminum 1.54 in.
Frequently asked questions
What is the coefficient of thermal expansion?
The fractional change in length per degree of temperature change.
How much does steel expand per degree?
About 6.5 millionths of its length per °F, or 0.78 in per 100 ft per 100 °F.
Why does PVC need expansion joints?
It expands about four times as much as steel.
Does area or volume expand too?
Yes. Area expands about 2α and volume about 3α for most solids.
Updated October 2026. Results are estimates for education, not financial or medical advice. All math runs in your browser; nothing you type is sent anywhere.