The exact area of effect for spells

I'm pretty sure that I saw a guide where it explained the exact area of effect for spells.

For example

Nearby : 10 feet
Adjacent : 8 feet
In the area : 30 feet

etc etc etc (these numbers are made up)

If anyone could give me a link to that page, I would really appreciate it.
I've been looking for that page for 30 min, but I could not find it.

Thanks in advance