Measure the pool’s length, width, and average depth in feet
Multiply length × width × average depth to get cubic feet
Multiply cubic feet by 7.48 to convert to gallons
For a round pool, measure diameter and average depth in feet
Divide diameter by 2 to get the radius
Multiply 3.1416 × radius × radius × average depth to get cubic feet
Multiply cubic feet by 7.48 to convert to gallons
For an oval pool, multiply length × width × average depth × 5.9
For a rectangular pool, use length × width × average depth × 7.48
For a circular pool, use diameter × diameter × average depth × 5.9
Round the result to the nearest gallon