How Can I Calculate My Swimming Pool’s Capacity?

Knowing your pool size is crucial when using or purchasing any pool equipment or chemicals. You need to know how much water your pool holds in order to get the right equipment or to use the right amount of chemicals to balance the water. Calculating a pool’s capacity varies depending on your pool’s shape, dimensions, and average depth.
The following are a few simple formulas to calculate an estimate of your pool capacity. We recommend choosing equipment or chemicals that are rated for a capacity a little higher than your own.
First: Determine the Average Depth (AD) of your pool with the following equation:
Depth of Deep End + Depth of Shallow End ÷ 2
Example: If your Deep End = 12’ and your Shallow End = 4’, your Average Depth is 8’ [12 + 4 = 16 ÷ 2 = 8]. We will use 8’ as the Average Depth for all of these examples.
Second: Use your Average Depth to complete the capacity equation based on your pool’s shape
rectangle pool measurementsCircle pool measurementsOval pool measurements
Rectangular Swimming Pools:
Length x Width x Average Depth x 7.5 = Total Gallons
Example: 32’ x 16’ x 8’ x 7.5 = 30,720 gallons
Circular Swimming Pools:
Long Diameter x Short Diameter x Average Depth x 5.9 = Total Gallons
Example: (where Diameter= 20’) 400 x 8 x 5.9 = 18, 880
Oval Swimming Pools:
Long Diameter x Short Diameter x Average Depth x 5.9 = Total Gallons
Example: 30 x 20 x 8 x 5.9 = 28,320 gallons
Irregular Swimming Pools:
You can either ask your pool installer or estimate based on what shape your pool most resembles.