So I've always run Grease as a 10' radius, the plus shape area described below. My current DM is trying to explain Grease as a 5' radius as below. I'm just trying to get some clarity as I've found nothing outright. As I've understood this is cast on the grid intersection and would make it the 10' radius.
Spell templates
Target one object or 10-ft. square
A 10 foot square is a square 10 feet on a side. That is an area of 100 square feet.
A 5-foot-radius circle is 5x5x 3.1416 or 78.54 square feet.
A 10-foot-radius circle is 10x10x 3.1416 or 314.6 square feet.
Your 10-foot-radius theory makes the spell cover more than 3 times the actual area allowed by the CRB.
The diagram showing a 5-foot radius, covering 4 squares, is exactly 100 square feet, or precisely what the spell description says.
