How many gallons in a 12foot diameter by 30 inches high pool?

12 in = 1 ft

radius = diameter ÷ 2

Assuming those are internal dimensions, the volume of the pool is:

volume = π x radius2 x depth

= π x (12 ft ÷ 2)2 x (30 ÷ 12) ft

= 90π cu ft

≈ 282.74 cu ft

Conversion to gallons depends upon which gallon you're using:

• 1 cu ft ≈ 6.23 imperial gallons → 282.74 cu ft ≈ 1761.16 imp gallons
• 1 cu ft ≈ 7.48 US gallons → 282.74 cu ft ≈ 2115.07 US gallons