How do I calculate the volume of water in my pool?

For square or rectangular pools, multiply the length in feet by the width in feet by the average depth in feet by 7.5 to find the number of gallons of water in your pool. For round pools, multiply the diameter of the pool in feet by itself, then multiply by the average depth in feet. Multiply that result by 5.9. For oval pools, multiply the width of the pool in feet at the widest point by the length of the pool in feet at the longest point, then multiply by the average depth in feet. Multiply that result by 5.9.