How many gallons of water in a pool 12 feet across and 36 inches deep?

Answer 1

I'm going to have to assume that the pool is circular.

Volume = (pi) (R)2 x (depth)

Radius of a circle = 1/2 of the distance across = 6-ft

36 inches = 3 ft

Volume = (pi) x (6)2 x (3) = 339.29 cubic feet = 2,538.1 gallons

That's the volume of the pool, up to the 3-foot rim.

I have no way to know how much water is in it.