Stefan-Boltzmann Calculator

About this calculator

This calculator finds the power radiated by an object using the Stefan-Boltzmann law, P = εσAT⁴, where ε is emissivity, σ is the Stefan-Boltzmann constant (5.67×10⁻⁸ W/m²K⁴), A is surface area, and T is absolute temperature in kelvin. Because power scales with the fourth power of temperature, small temperature changes produce large changes in radiated energy.

Physics and engineering students use it for thermodynamics and heat-transfer coursework, and it's the same law astronomers use to estimate a star's luminosity from its temperature and size, and engineers use to calculate heat loss from hot surfaces like furnaces or spacecraft.