While this information is not available within the game, you can find these values in the planetsize.txt file in your data repertory.
The most important think is the number of facilities you can built on a given, and it is as follow:
- Tiny: 5 if breathable, 1 otherwise.
- Small: 10 if breathable, 2 otherwise.
- Medium: 15 if breathable, 3 otherwise.
- Large: 20 if breathable, 4 otherwise.
- Huge: 25 if breathable, 5 otherwise.
- Ringworlds give 100 facilities if breathable, 50 otherwise, and Sphereworlds 200 facilities, or 100 if domed, but these planets are not exactly usual.
