The Swimming Pool Water Capacity in Gallons (Round) calculator determines the capacity of a round swimming pool based on the diameter of the pool and the desired depth of water and the approximate time to fill the pool with a garden hose.

INSTRUCTIONS: Enter the following:

• (D) Diameter of Pool
• (wD) Depth of Water in Pool 
• (FR) Hose Flow Rate

The Math / Science

This equation determines the amount of water a constant depth circular or round swimming pool can hold or it's volume capacity (V) by using cylinder volume equation, multiplying the volume in cubic feet times 7.5 gallons (gal.) because there are 7.5 gallons of water in 1 cubic foot. If you are calculating the capacity of a circular hot tub with seats around the edges simply run this equation twice, once using the measurements from the bottom to the top of the seats and again from the top of the seats to the fill line of the hot tub.

The formula for the volume of a circular swimming pool is:

       V = π * (D/2)² * wD

where:

• V = Volume (water capacity) of a round swimming pool
• D = Diameter of the round swimming pool
• wD = Depth of water in pool

The time to fill the pool is based on the range of flow rate for garden hoses of between 9 gallons per minute to 17 gallons per minute.  A default of 12 gallons per minute is provided.  This should be used as an estimate.

The formula for the time to fill a circular pool is:

       T =  V / FR

where:

• T = Time to fill the circular pool
• V = Volume Capacity of the pool
• FR = Flow Rate of the garden hose being used.

Swimming Pool Calculators

• Water Capacity and Time to fill an Oval Swimming Pool
• Water Capacity and Time to fill a Round Swimming Pool
• Water Capacity and Time to fill a Rectangular Swimming Pool