Pool Calculator: Find Your Pool’s Volume, Cost, and Chemistry

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About This Pool Calculator

This pool calculator can be used to calculate your pool’s volume in gallons, surface area, estimated cost of installation, and chemicals needed for water balancing.

To calculate how many gallons of water are needed to fill your swimming pool, the pool volume calculator uses the dimensions of your pool, including the depth of your pool, to find out how much water it can hold. When using the pool volume calculator, the pool depth would be measured from the bottom of the pool to where the water will be filled up to. This will be less than the actual height of your pool walls.

In addition to finding your pool's volume in gallons and liters, the calculator also finds your pool's surface area in square feet. You can also find this by using a square footage calculator. Finally, the pool volume calculator gives an estimated pool cost range for the dimensions that you have entered.

For a more detailed pool cost breakdown, the pool cost calculator can be used. With the pool cost calculator, you can add and select features to your pool, such as deck jets, water slides, waterfalls, a hot tub or spa, LED lighting, pool water heaters, and diving boards. Besides your pool size, the cost of your pool will also depend on the pool material that you select and the state that you are located in.

The pool chemical calculator determines how much of a chemical will need to be added to the pool for some common water quality parameters. The pool chemical calculator can be used to calculate free chlorine, pH levels, total alkalinity, borate, calcium hardness, cyanuric acid, and salt PPM.

Pool Volume Calculations

How Many Gallons Is My Pool?

The pool volume chart below tells you how many gallons of water are needed to fill common pool sizes. For a more specific number, the pool volume calculator at the top of this page allows you to calculate how many gallons are in your pool based on custom dimensions. You can also use the pool volume formulas below to calculate it manually.

Pool Volume Chart

Pool Size (Feet)Gallons (3’ Depth)Gallons (4’ Depth)Gallons (5’ Depth)
10x20 Rectangle4,5006,0007,500
12x24 Rectangle6,4808.64010,800
14x28 Rectangle8,82011,76014,700
15x30 Rectangle10,12513,50016,875
16x32 Rectangle11,52015,36019,200
18x36 Rectangle14,58019,44024,300
20x40 Rectangle18,00024,00030,000
25x50 Rectangle28,12537,50046,875
18’ Round4,5046,0057,507
24’ Round8,00710,67613,345
28’ Round10,89914,53218,165
16x24 Kidney7,75510,34012,925
16x30 Kidney9,69412,92516,157

How Much Will It Cost to Fill My Pool With Water?

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To fill your 15,000 gallon swimming pool it will cost

$75.00

Rectangular Pool Volume Calculation

To find the volume of a rectangular pool:

  1. Find the average pool depth

    If your pool has a slope with a shallow end and a deep end, you will need to find the average depth of the pool. To do this, add the shallow-end depth with the deep-end depth, and then divide this by two. Some pools do not have a slope and have a flat bottom. Flat bottoms are common in round and lap pools. If you have a flat-bottom pool, the average depth would simply be the depth of the pool.

    Average depth:

  2. Find the volume of the rectangular pool
  3. Using feet as the unit of measurement, the formula for the volume of a rectangle is:

    Rectangle Volume = Length x Width x Average Depth

  4. Calculate the volume in gallons
  5. Each cubic foot is 7.48052 gallons of water. Once you have found the volume of the rectangular pool, multiply by 7.48052 to get the volume in gallons.

    Gallons = Volume in Cubic Feet x 7.48052

    You can also calculate the pool surface area for a rectangular pool by multiplying the length by the width in feet. This will give you the square footage of the rectangular pool's surface area.

Round/Circular Pool Volume Calculation

To find the volume of a round or circular swimming pool:

  1. Find the pool’s radius
  2. A circular pool’s radius is the diameter of the pool divided by two.

  3. Find the volume of the round/circular pool
  4. Using feet as the unit of measurement, the formula for the volume of a circular pool is:

    Circular Pool Volume = (Radius x Radius) x Pool Depth x π

    Where pi (π) is 3.14159265359.

  5. Calculate the volume in gallons
  6. Each cubic foot is 7.48052 gallons of water. Once you have found the volume of the circular pool, multiply by 7.48052 to get the volume in gallons.

    Gallons = Volume in Cubic Feet x 7.48052

    You can also calculate the pool surface area for a circular pool by using this formula:

    Circular Pool’s Surface Area = (Radius x Radius) x π

    This will give you the square footage of the circular pool's surface area.

Kidney/Oblong Pool Volume Calculation

To find the volume of a kidney or oblong-shaped pool:

  1. Find the average pool depth
  2. Kidney and oblong-shaped swimming pools usually have a shallow-end on one side and a deep-end on the other. The kidney or oblong shape allows for these ends to be naturally separated from each other. When calculating a kidney/oblong pool’s volume, you will first need to find the average depth of the pool.

    Average depth:

  3. Find the surface area of the kidney/oblong-shaped pool
  4. You will need to measure the width of a kidney/oblong pool as the widest points of each half. One side would often have a longer width than the other. The pool calculator allows for a large width input and a small width input. If the widths are the same, then the values for the large width and small width would also be the same.

    Kidney/Oblong Pool Surface Area = (Large Width + Small Width) x Length x 0.45

  5. Find the volume of the kidney/oblong pool
  6. Using feet as the unit of measurement, you will use the surface area that you calculated in the previous step. The formula for the volume of a kidney/oblong pool is:

    Kidney/Oblong Pool Volume = Pool Surface Area x Average Depth

  7. Calculate the volume in gallons
  8. Each cubic foot is 7.48052 gallons of water. Once you have found the volume of the kidney/oblong pool, multiply by 7.48052 to get the volume in gallons.

    Gallons = Volume in Cubic Feet x 7.48052

L-Shaped Pool Volume Calculation

To find the volume of an L-shaped pool:

  1. Find the average pool depth
  2. L-shaped pools commonly have one section being shallow, while another section has a slope down to a deep-end. This pool calculator assumes that the smaller part of the L-shape is shallow water, while the larger part of the L-shape slopes down to the deep-end.

    To calculate the average pool depth:

    Average depth:

  3. Find the volume of the rectangular pool
  4. The average pool depth will only apply to the larger part of the L-shape pool. When calculating the volume of an L-shape pool, you will need to calculate it as two separate sections. One section uses the shallow-end depth, while the other section uses the pool’s average depth.

    Using feet as the unit of measurement, the formula for the volume of an L-shape with a sloping deep-end is:

    L-Shape Volume = (Length 1 x Width 1 x Average Depth) + (Length 2 x Width 2 x Shallow End Depth)

  5. Calculate the volume in gallons
  6. Each cubic foot is 7.48052 gallons of water. Once you have found the volume of the L-shape pool, multiply by 7.48052 to get the volume in gallons.

    Gallons = Volume in Cubic Feet x 7.48052

    You can also calculate the pool surface area for a rectangular pool by multiplying the length by the width in feet. This will give you the square footage of the L-shaped pool's surface area.

    L-Shaped Pool Surface Area = (Length 1 x Width 1) + (Length 2 x Width 2)

Pool Cost Calculations

How Much Does a Pool Cost?

The cost of a pool generally starts from $50 per square foot. This means that a 16’ x 32’ rectangular pool would cost around $25,600 without any additional features. The cost will increase depending on the pool material, type, features, and location. In-ground pools add value to your home, but they are much more expensive than above-ground pools, such as Intex pools. Intex pools and above-ground pools do not add as much value to your home, and in some cases, they may even decrease your home’s value if they are unwanted by future buyers.

Pool Material

The three most common types of pool material are vinyl, fiberglass, and concrete. Out of the three, concrete is the most popular material used for pools, but it's also the most expensive. Gunite pools are similar to concrete pools in that they also use concrete, however, the method that gunite pools are built allows them to be more durable than concrete pools. You can estimate the cost of concrete by using a concrete calculator.

Vinyl pools are the cheapest out of the three. A fiberglass pool would cost about $15 more per square foot compared to a vinyl pool, while a concrete pool would cost about $25 more per square foot compared to a vinyl pool. If you know the dimensions of your pool, a square footage calculator can be used to find the surface area of your pool. Liners can be set out underneath above-ground pools. You may also use pea gravel as a base for fiberglass pools.

Pool Material - Example Cost for a 16’ x 32’ Pool

Pool MaterialCost
Vinyl$25,600
Fiberglass$33,280
Concrete$38,400

Location

Your location can greatly affect the cost of installing a pool. Some states have high labor costs, while others may have lower labor costs. Your local climate can also affect the cost of the pool, not just in construction costs, but in operating and maintaining it. Pools are generally cheaper in southern states with warmer climates.

Pool Features

Add-on features can improve your enjoyment of the pool, but it also adds costs. Some features, such as deck jets, LED lights, and pool bubblers, may have multiple items installed. The cost of other items, such as stairs or zero-entry/beach-entry pools, depend on the size. You can use a stair calculator to find out the size of the pool stairs or a fence calculator to estimate a pool fence’s cost and materials. The U.S. Consumer Product Safety Commission recommends pool fences to be at least 4 feet tall, but does not require pool fences nationally. Some states and counties have building codes that require pool fences to be at least 4 feet or 5 feet tall.

Here are some common pool features with their typical cost.

Cost of Pool Feature Add-Ons

Feature Add-OnsCost
LED Pool Lighting$1,500
Saltwater Pool System$1,500
Diving Board$800
Water Slide$1,000 Basic
$10,000 Rock Slide
Deck Jets$2,000
Pool Bubblers$2,000
Waterfall$500 Small
$6,000 Large
Hot Tub$10,000
Inground Pool Heater$500-$2,000 Electric
$4,000 Solar
Pool Cover$200 Tarp
$6,000 Automatic motorized cover
Pool Fence$1,000

Pool Chemical Calculations

Swimming pool owners need to pay attention to their pool water chemistry to make sure that your pool is safe to use while keeping the pool water clear and algae-free. The following six readings are important: free chlorine, pH level, total alkalinity, borate, calcium hardness, and cyanuric acid. If you have a saltwater pool, you'll also want to pay attention to salt PPM in your pool.

Free Chlorine

Chlorine kills bacteria and algae and sanitizes your pool water. Free chlorine is the amount of chlorine still available in your water, which excludes chlorine that has already been used up to kill bacteria. Having a free chlorine reading of zero means that all of the chlorine is being used and that the amount that you are adding is not enough to clean the water.

The Centers for Disease Control and Prevention (CDC) recommends a free chlorine level of at least 1 ppm in pools and 3 ppm in hot tubs. If you are using cyanuric acid as a chlorine stabilizer, the effectiveness of the chlorine will be reduced. The CDC recommends a free chlorine level of 3 ppm if you are using a chlorine stabilizer (cyanuric acid) in pools, or if you are using dichlor or trichlor.

To increase your free chlorine reading, you can use chlorine tablets, granules, powder, liquid household bleach, or chlorine gas. Chlorine gas is usually only used in large public pools. For residential pools, tablets, powders, and liquid bleach are more convenient options.

These chemicals usually have a percentage. This percentage is the amount of active chlorine that it contains. For example, household bleach may contain 6% sodium hypochlorite (chlorine), while chlorine gas is 100% chlorine. The lower the percentage of chlorine, the more chemicals are needed.

Other common chlorine types are dichlor, which comes in powder/granules, and trichlor, which comes in tablets or sticks.

Optimal Free Chlorine Level

The CDC recommends a free chlorine level of at least 1 ppm in pools and 3 ppm in hot tubs.

Free Chlorine Types

Chemical TypeTo Increase Free Chlorine By 1 ppm, Add:
Liquid Bleach (Sodium Hypochlorite 6%)2.14 oz per 1,000 gallons
Powder/Granules (Dichlor 56%)0.24 oz per 1,000 gallons
Chlorine Granules (Calcium Hypochlorite 68%)0.20 oz per 1,000 gallons
Chlorine Tablets (Trichlor 90%)0.15 oz per 1,000 gallons
Chlorine Gas (100%)0.13 oz per 1,000 gallons

pH Level

Your pool's pH level affects the ability of chlorine to kill germs. It can also create irritation to swimmers if the pool's pH level is too high or low. The CDC recommends a pH level between 7.2 and 7.8. Having a pH level higher than 8 can cause skin and eye irritation and makes chlorine less effective. Having water that is too acidic with a pH level under 7 may cause damage to your pool liner, corrosion, as well as skin and eye irritation.

To raise your pool's pH level, you can add soda ash/washing soda (sodium carbonate), lye/caustic soda (sodium hydroxide), or borax (sodium borate). If your pool's pH level is too high, you can lower it by adding muriatic acid (hydrochloric acid) or sodium bisulfate).

Total alkalinity and borate levels can also affect your pool's pH level. If your total alkalinity is too low, it would be harder to increase your pool's pH level. Aerating your pool water can also help raise pH, however, it may reduce your pool's chlorine levels.

Optimal pH Level

The ideal pool pH level is 7.2 to 7.8.

Total Alkalinity

Total alkalinity is the amount of dissolved alkalis in your pool water. Total alkalinity is important because alkalis neutralize acids. In other words, it buffers against your pH level from decreasing and becoming acidic.

The most common ways to increase total alkalinity is to add baking soda (sodium bicarbonate) or soda ash/washing soda (sodium carbonate), which acts as a pH buffer. This can also increase your pool's pH level. To decrease total alkalinity, muriatic acid (hydrochloric acid) or sodium bisulfate can be added.

Optimal Total Alkalinity Level

The ideal total alkalinity level is 100 PPM.

Total Alkalinity Types

IncreaseTo Increase by 10 ppm
Baking Soda (Sodium Bicarbonate)2.24 oz per 1,000 gallons
Soda Ash/Washing Soda (Sodium Carbonate)1.40 oz per 1,000 gallons
DecreaseTo Decrease by 10 ppm
Muriatic Acid (Hydrochloric Acid)2.6 oz per 1,000 gallons
Sodium Bisulfate3.36 oz per 1,000 gallons

Borate

Just like how total alkalinity is a pH buffer that prevents pH from falling, borate is also a pH buffer that prevents pH from rising. Borate is permanent, which means that you will only need to add it to your pool once. Boric acid and borax (sodium borate) are commonly added to increase borate levels.

Optimal Borate Level

The ideal borate level is 50 PPM.

Borate Types

IncreaseTo Increase by 10 ppm
Borax (Sodium Borate)12 oz per 1,000 gallons
Boric Acid7.6 oz per 1,000 gallons

Calcium Hardness

Calcium hardness is how much calcium is in the water. Calcium hardness is needed to balance your pool's total alkalinity. Too low of calcium hardness can cause corrosion, while too high can cause calcium deposits and flakes. To increase calcium hardness, calcium chloride can be added to the pool water.

Optimal Calcium Hardness Level

The ideal calcium hardness level is 200-400 ppm.

How Much Calcium Chloride to Add

IncreaseTo Increase by 10 ppm
Calcium Chloride1.5 oz per 1,000 gallons

Cyanuric Acid

Cyanuric acid is a chlorine stabilizer that prevents free chlorine from reacting with UV light. This allows chlorine to remain in the water for longer. However, cyanuric acid makes chlorine less effective, which means that you will need to add more chlorine the higher your cyanuric acid levels are. Cyanuric acid is also sometimes called a swimming pool conditioner.

Higher cyanuric acid levels are needed for saltwater pools. If you are using dichlor or trichlor as your pool’s chlorine, you will not need to add additional cyanuric acid. That’s because dichlor and trichlor already contain cyanuric acid.

Optimal Cyanuric Acid Level

The ideal cyanuric acid level is 50 ppm.

How Much Cyanuric Acid to Add

IncreaseTo Increase by 10 ppm
Chlorine Stabilizer (Cyanuric Acid)1.3 oz per 1,000 gallons

Salt PPM

Salt PPM is the amount of dissolved salt in a saltwater pool. With saltwater pools, a salt chlorine generator creates chlorine using salt. If salt PPM levels are too low, your salt chlorine generator might not be creating enough chlorine. Too high salt PPM levels may cause corrosion through high salinity or cause your pool water to taste salty.

Optimal Salt PPM Level

The ideal Salt ppm for a saltwater pool is 3,200 ppm.

How Much Salt to Add

IncreaseTo Increase by 100 ppm
Salt (Sodium Chloride)0.84 lb per 1,000 gallons
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