Thermal expansion calculator
Estimate expansion or contraction across a temperature change. Supply the linear coefficient for your material and temperature range.
Temperatures from absolute zero to 10,000 K and calculated linear changes within ±10% of starting length. These calculation bounds do not establish physical accuracy. Only constant-coefficient, unconstrained linear expansion is modeled. Change the input or settings to update your result. Results update as you type. Up to 1,000,000 characters.
Your result
How to use Thermal expansion calculator
- Enter starting length and the initial and final temperatures.
- Supply a linear coefficient with its own unit.
- Review expansion or contraction and download the calculation.
Useful next steps
Use the linear expansion coefficient
The approximation is change in length = starting length × coefficient × temperature change. Enter the coefficient in millionths per kelvin or millionths per degree Fahrenheit. Coefficient units are independent of the temperature display units. A temperature interval of one kelvin equals one Celsius degree, while a Fahrenheit interval is 5/9 as large.
Use data for your actual material
The starting coefficient is an editable example. Select a value from the specific material's data over the temperature range being considered. A single constant does not describe every alloy, temperature or phase. Negative coefficients are accepted, and cooling can cause contraction.
Read signed length changes
Positive change means expansion; negative change means contraction. The calculator shows millimetres, inches, percentage change and final length. For a 1 metre length with a coefficient of 12 millionths/K, warming from 20°C to 80°C gives a 0.72 mm increase under this model.
Know what the approximation omits
The object is assumed to expand freely and be at a uniform temperature. Stress, restraint, creep, phase changes and expansion-joint design are not calculated. Download CSV, text or JSON with the coefficient, temperature interval and assumptions used.