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Thermal Diffusivity Calculator — α, k, Density & Specific Heat
Solve thermal diffusivity from conductivity, density and specific heat, or reverse-solve any one property. See volumetric heat capacity and practical mm²/s output.
Last updated: September 17, 2026
Results
Leave exactly one of k, density, Cp or α blank
Formula, example and limits
α=k/(ρCp); k=αρCp; ρ=k/(αCp); Cp=k/(αρ).
Water near room temperature with k=0.607 W/m·K, ρ=997 kg/m³ and Cp=4182 J/kg·K gives α≈1.456×10⁻⁷ m²/s, or 0.1456 mm²/s.
- Treat properties as constant at the modeled temperature.
- Use mutually consistent SI properties; material values can vary with temperature, composition and direction.
Frequently asked questions
What does thermal diffusivity measure?
It compares a material’s ability to conduct heat with its ability to store thermal energy, so higher α generally means temperature disturbances spread faster.
What are the SI units of thermal diffusivity?
Square metres per second (m²/s). This calculator also reports mm²/s for convenient material comparison.
How is thermal diffusivity related to Prandtl number?
For a fluid, Prandtl number is kinematic viscosity divided by thermal diffusivity, Pr=ν/α.