Make temperature movement visible.
Estimate free thermal movement of steel, aluminum or a custom material over a user-defined member length, temperature range and joint spacing.
Project inputs
Defaults are examples, not recommendations. Replace them with traceable project assumptions.
Screening result
Updated from the inputs at left.
Preliminary decision support only. Confirm inputs, governing standards and final conclusions with the responsible qualified professional before design, procurement or construction.
Method and assumptions
Free movement follows ΔL = α × L × ΔT. The coefficient is converted from micrometres per metre-degree Celsius, then applied to the continuous length and to the lesser of joint spacing or total length.
- The result is total free expansion across the full temperature swing.
- Movement from a neutral installation temperature is smaller and direction-dependent.
- Steel and aluminum defaults are illustrative values only.
Thermal expansion with units you can check
Free linear movement follows ΔL = α × L × ΔT. With α entered in µm/(m·°C), length in metres and temperature difference in °C, multiply by 10⁻⁶ and then by 1,000 to report millimetres. See the OpenStax explanation of linear thermal expansion.
Worked example: 20 m from 20°C to 80°C
The temperature difference is 60°C. An illustrative steel coefficient of 12 gives 14.4 mm; the tool’s rounded aluminum preset of 23 gives 27.6 mm. These presets are examples, not alloy certifications.
Hydro’s 6063 alloy sheet lists an average coefficient of 13.0 × 10⁻⁶ per °F over 68–212°F (20–100°C). Converting the temperature interval gives 23.4 µm/(m·°C). Entering that custom value gives 23.4 × 10⁻⁶ × 20 × 60 × 1,000 = 28.1 mm (rounded). A 10 m segment has 14.0 mm of free movement over the same range.
Load the 6063 arithmetic exampleMovement is not an installation gap
The result describes unconstrained movement across the entered temperature range. It does not determine joint locations, slot sizes, fastening details or a gap at installation temperature. Restraint, alloy, component temperature and the manufacturer’s tested system details require separate review. Use component temperatures rather than assuming that ambient air temperatures are sufficient.