What this calculator does
Thermal Diffusivity works out how quickly a material equalises temperature, from conductivity, density and specific heat. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
Formulaα = k / (ρ·Cp)
The inputs explained
| Field | What to enter |
|---|---|
| Thermal conductivity (k) (W/m·K) | A number, measured in W/m·K. Starts at 0.6. |
| Density (ρ) (kg/m³) | A number, measured in kg/m³. Starts at 1000. |
| Specific heat capacity (Cp) (J/kg·K) | A number, measured in J/kg·K. Starts at 4186. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with thermal conductivity (k)
Every other input is held at the calculator’s starting values while thermal conductivity (k) varies. Select any row to load that scenario into the calculator.
How the answer changes with thermal conductivity (k)
| Thermal conductivity (k) (W/m·K) | Thermal diffusivity (α) | Thermal diffusivity | Volumetric heat capacity (ρ·Cp) |
|---|---|---|---|
| 0.3 | 7.1667e-8 m²/s | 0.071667 mm²/s | 4,186,000 J/m³·K |
| 0.45 | 1.0750e-7 m²/s | 0.107501 mm²/s | 4,186,000 J/m³·K |
| 0.6 | 1.4333e-7 m²/s | 0.143335 mm²/s | 4,186,000 J/m³·K |
| 0.9 | 2.1500e-7 m²/s | 0.215002 mm²/s | 4,186,000 J/m³·K |
| 1.2 | 2.8667e-7 m²/s | 0.286670 mm²/s | 4,186,000 J/m³·K |
| 1.8 | 4.3000e-7 m²/s | 0.430005 mm²/s | 4,186,000 J/m³·K |