Pool Volume Calculator: Find Water Volume in Your Pool

Every time you add any chemical to your pool, for calculations, you need to know your pool water volume.

If you haven’t yet figured out the volume of water in your pool, just select the type of pool you have and fill in the measurements in the pool volume calculator below.

Water Volume Calculator

Select your pool type

Results in the calculator are rounded off to the nearest whole numbers. You don’t have to worry about that, as your pool does not require exact precise calculations like chemistry titrations.

Note: For height measurement, don’t measure wall height. Measure the height of water in your pool from the bottom.

In this article, I will cover how these calculations work. More complex pools need more calculations, which will be explained later.

How to Calculate Pool Water Volume

To get started with calculating pool water volume, you first need to measure pool dimensions. basically you need pool surface area and pool depth.

For that you need to know following metrics.

  • Length (L)
  • Width (W)
  • Depth (D, Shallow and Deep)
  • Diameter (d)
  • Radius (r)

Multiplying Length (L) with Width (W) will give you the surface area of the pool. Then multiply area with depth and you will get the volume calculations.

The volume you get will be in cubic feet volume, and to convert it into gallons, you need to multiply by a value of 7.5.

Let’s find out how these calculations work in different shapes of pools.

Rectangular Pool Volume Calculation

In this case, your pool Width and Length will be easier to calculate, but you need to be sure about the depth. There are two calculation types based on how the bottom of your pool.

Constant Depth

In this cases Length (L) x Width (W) x Depth (D) x 7.5 = Pool Volume (gallons)

For example, if your pool is 15 feet long,10 feet wide, and 5 feet deep, then the pool volume will be

15 x 10 x 5 x 7.5 = 5,625 gallons

Variable Depth

If your pool has variable depths, then you need to average out the depth for final volume calculations. With a gradual slop, the calculation will be different than sudden depth drops.

In case the change in depths is not regular, treat different parts as two different pools and use constant depth formula for individual components, and add both of them for the final volume.

Rectangular pool shape

If the slop is gradual, then you can add Deep Depth and Shallow Depth and divide by 2 to get an average depth.

Length (L) x Width (W) x [(Shallow Depth + Deep Depth)/2] x 7.5 = Volume (gallons)

For example, if your pool Length is 15 feet, width is 10 feet, Shallow Depth is 4 feet, and Deep Depth is 8 feet, then pool volume will be

15 x 10 x [(4 + 8)/2] x 7.5 = 6,750 gallons

Round Pool Volume Calculation

To calculate the volume of the round pool, you need to get the values used in the formula

3.14 x Radius Squared (r2) x Average Depth x 7.5 = Volume (gallons)

To find out the radius, measure the pool diameter (your round pool’s widest part) and divide by 2.

round pool shape

For example, if your pool diameter is 24 feet, its radius will with 12 feet. If the Depth is 5 feet, then the water volume will be

3.14 x (12 x 12) x 5 x 7.5 = 16,956 gallons

If your round pool has variable depth, then you need to calculate average depth by adding Shallow depth and Deep Depth and dividing that by 2.

Oval Pool Volume Calculation

Calculations for an oval pool are almost similar to the rectangular pool by adding one more multiplication.

oval pool shape

Here is the formula:

π ÷ 4 X Length (L) × Width (W) × Depth (D) × 7.5 = Volume (gallons)

For example, if your pool length is 15 feet, width is 10 feet, and depth is 5 feet then the water volume will be

(3.14/4) x 15 x 10 x 5 x 7.5 = 4,415 gallons

If your pool has variable depths, you need to average them.

Always measure the depth from the water levels and not pool height for example, if your pool height is 5 feet, but it is filled up to 4 feet, then you will overestimate the pool volume by 20% if you use pool height.

This can seriously affect your calculations for chemicals you are going to use in the pool and imbalance pool chemistry.

Kidney-Shaped Pool Volume Calculation

If your pool is kidney shaped, then you will have two variable widths to deal with.

kidney-shaped pool

Use this formula to calculate the pool volume water of a kidney-shaped pool.

[(Short Width + Long Width) x 0.45] x Length (L) x Average Depth x 7.5 = Volume (gallons)

For example, if your kidney-shaped pool has short width of 6 feet and long width of 10 feet, a Length of 15 feet, and depth of 5 feet, then volume will be:

[(6 + 10) x 0.45] x 15 x 5 x 7.5 = 4,050 gallons

As in other cases, if the depth is variable, find the average depth by adding two depths and dividing by 2.

Pool Volume Calculations for Variable Pool Shapes

If your pool shape does not fit into any of the above shapes, divide your pool into small pockets that fit any criteria, like round or rectangular.

Then calculate the water volume for each component using formulas or the volume calculator above and, in the end, add all of them to get the final pool water volume.

This way, you will get a near-accurate reading that will be good enough to use for all the calculations.

Standard Pool Volumes

Here are a few standard reference charts that you can have a quick look at.

Above Ground Pools

All calculations assume water depth is less than pool height by 6″.

Pool Size48″ Height52″ Height
15ft Round4,640 gals5,080 gals
18ft Round6,680 gals7,316 gals
20ft Round8,245 gals9,030 gals
24ft Round11,875 gals13,000 gals
27ft Round15,030 gals16,460 gals
30ft Round18,555 gals20,320 gals
33ft Round22,450 gals24,590 gals
12x24ft Oval5,950 gals6,515 gals
15x30ft Oval9,290 gals10,180 gals
16x32ft Oval10,570 gals11,580 gals
18x38ft Oval14,125 gals15,470 gals

In-Ground Pool

Here depth measurements represent actual water depth.

Pool Size3ft Avg. Depth4ft Avg. Depth5ft Avg. Depth
12x24ft Rect6,430 gals8,640 gals10,800 gals
15x30ft Rect10,125 gals13,500 gals16,870 gals
16x32ft Rect11,520 gals15,360 gals19,200 gals
18x38ft Rect15,390 gals20,520 gals25,650 gals
20x40ft Rect18,000 gals24,000 gals30,000 gals
16x32ft Oval9,062 gals12,080 gals15,100 gals
18x38ft Oval12,100 gals16,140 gals20,180 gals
20x40ft Oval14,160 gals18,880 gals23,600 gals
15ft Round3,980 gals5,300 gals6,630 gals
20ft Round7,070 gals9,425 gals11,780 gals
30ft Round15,900 gals21,200 gals26,500 gals
33ft Round19,250 gals25,660 gals32,070 gals

All Pool Owners Need to Know Their Pool Water Volume

Everyone who manage a pool need to know how much water volume they are dealing with.

You need to know the water volume to calculate how much chemicals you need to add. For installing a pool pump, you need to find out the water volume so that you buy right sized pool pump.

Similarly, when installing pool heaters, you need to know how much water there is that requires heating so that you can install a right sized heater.

If you are still not sure about your pool water volume for any reason, take professional help to find it.

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