Uh oh! Wolfram|Alpha doesn't run without JavaScript.
Please enable JavaScript. If you don't know how, you can find instructions
here
.
Once you've done that, refresh this page to start using Wolfram|Alpha.
(stefan constant) (8000 K)^4 * (4 pi) (200 m)^2
Natural Language
Math Input
Extended Keyboard
Examples
Upload
Random
