The total emissive power of a blackbody is then calculated as, E b = ∫ ∫ 0 ∞ ∞ π π I λ λ , b d λ λ . The solution of the above integral yields a remarkably elegant equation for the total emissive power of a blackbody, the Stefan-Boltzmann law, which is given as, E b = σ σ T 4 where σ σ is the Steffan-Boltzmann constant.