On average, a 24-foot-by-52-inch round swimming pools holds slightly less than 14,000 gallons of water. This amount varies, however, depending on the exact dimensions and whether the pool is above or below ground.
To calculate how many gallons of water a pool is designed to hold, four measurements are needed. This includes the length, the width, average depth and the multiplier. The multiplier is dependent on the shape of the pool. For instance, the multiplier for round or oval pools is 5.9, while for rectangular or square pools it is 7.5. The formula used to determine the number of gallons is length times width times depth times multiplier equals gallons.