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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 measurements Circle pool measurements Oval 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.
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  • ginger

    I have a kidney shaped pool..low end 3′ deep end 7′ 18×36′ Had it epoxied 8 years ago. would like to know how many gal. of epoxy hp would i need. also, do i need 1 or 2 coats. what product would i use to patch first. thank you, ginger vas

    • PoolSupplyWorld

      Hi Ginger, thank you for your excellent question. The formula to figure out how many gallons your pool would need is to take the length x width x 1.60. Therefore, you would need approximately seven gallons. We would recommend the Kelly Technical Coatings Olympic Zeron White One Coat Epoxy – 1 Gallon. This Zeron is very heavy and you would only need to apply one coat. Please let us know if we can answer any other questions.

  • David Lewis

    I have a 30′ round above ground pool,what can I do for a solar cover real. Please Help.

  • Duane

    I have a Zodiac clear water LM2-24 system that is not working when I press the buttons but it has power.

    • PoolSupplyWorld

      Hi Duane, when your LM2-24 system has power but its buttons will not work, your pool’s actual salt level may be off or your cell may need to be cleaned. We recommend verifying that the cell is clean, and checking the actual salinity of your pool using AquaChek White Salt Test Strips. (The actual salt level should be around 4000 ppm, according to the manufacturer of your LM2-24.) If the salt level is low, you should add salt until your salinity reaches the recommended level. If it is high, you should drain your pool water some and add fresh water.

      Should your cell be clean and your salt level correct, it means your salt cell is bad and you should replace it with the Zodiac Clearwater LM2-24 Replacement Electrode (Cell). Please let us know if we can be of any further assistance.

  • CHARLES J CARTER

    i HAVE A SQUARE POOL 38×16 AVERAGE DEPTH 4.5 WHAT IS THE BEST SAND FILTER OR WHAT IS THE BEST TYPE FILTER AVAILABLE?

  • WAYNE ST. CLAIRE

    I have a STA-RITE System 3 Modular System that has developed a pin hole leak in the lower tank half. It is Model Number S8M150. My pool is about 15,000 gallons. My pool builder says STA-RITE has discontinued this model and they are no longer installing them. Are these still available? If not, what is a comparable current model? We have had great results for 14 years with this system. We are also experiencing some problems with our STA-RITE Heater. Is is better to replace the entire system or can we just replace the lower tank half of the filter system/ Your thoughts please.

    • PoolSupplyWorld

      Hi Wayne, a member of our sales team will contact you shortly to answer your questions and help you find the replacement parts or equipment you need. Thanks, and have a great day.

  • Ron Illinois

    I’m getting an 8′ board installed on average, how may feet are above the deck, and how many above water. Trying to determine if there’s enough walking space on the deck. I dont know the exact model.

    • PoolSupplyWorld

      Hi Ron, such measurements depend on the size of your pool, where your water level sits, the size of your deck, and the size of the board and its base. Typically, it will require a concrete pad of around 8′ x 4′ x 6′, in compliance with local safety codes. Each board will demand different installation requirements, and therefore we recommend contacting your board’s manufacturer as soon as you plan on installing it to ensure that you’re following all correct procedures. Please let us know if we can be of any further assistance.