# What is the Stefan Boltzmann constant?

5.670367 × 10^-8 kg s^-3 K^-4
Stefan Boltzmann constant is usually denoted by $\sigma$ and is the constant of proportionality in Stefan Boltzmann's law.
Here, $k$ is the Boltzmann constant, $h$ is Planck's constant, and $c$ is the speed of light in a vacuum.