How Many Gallons Are in My Pool?

house with a pool, or perhaps you just don’t remember how many gallons are in your pool. No matter the reason, it’s important information to have on hand in order to properly care for your pool.

You need to know pool gallons in order to maintain your pool properly, and the chemicals you use in your pool depend on how many gallons of water you have. Accurate measurements of your water ensure you add the correct amount of chemicals, maintain water quality, and maximize your pool's longevity. So, we’ve put together a guide with things like the steps to figuring out the answer and even pool gallon calculator equations to help you determine the number of gallons in your pool. So, let’s dive in and get started.

Step 1: Measure Your Pool

First things first, you need to gather the necessary measurements of your pool. The pool shape actually determines how you need to take these measurements. So, we’ve detailed the process below for the various shapes. 

How to Calculate How Many Gallons There Are in a Rectangular Pool: 

• Length: Measure the longest part.

• Width: Measure the widest part.

• Average Depth: For an accurate depth measurement, measure the depth at the shallow end and the deep end, then find the average. For example, if the shallow end is 3 feet and the deep end is 9 feet, the average depth is (3+9)/2 = 6 feet.

How to Calculate How Many Gallons There Are in a Round Pool:

• Diameter: Measure the distance across the pool at its widest point.

• Average Depth: Use the same method as for rectangular pools to find the average depth.

How to Calculate How Many Gallons There Are in an Oval Pool:

• Length: Measure the longest part.

• Width: Measure the widest part.

• Average Depth: As with other shapes, find the average depth.

How to Calculate How Many Gallons There Are in a Freeform Pool:

• Break the pool into simple geometric shapes (rectangles, circles, ovals).

• Measure the dimensions of each shape.

• Find the average depth of each section.

Once you have these measurements, you need to calculate the volume of your pool.

Step 2: Calculate the Volume

How do you calculate the volume of a pool, though? Well, again, it depends on the pool shape. Here are the equations you need to calculate pool gallons. 

Rectangular Pools:

Volume=Length×Width×Average Depth×7.5Volume=Length×Width×Average Depth×7.5

Round Pools:

Volume=(Diameter/2)2×π×Average Depth×7.5Volume=(Diameter/2)2×π×Average Depth×7.5

Oval Pools:

Volume=Length×Width×Average Depth×5.9Volume=Length×Width×Average Depth×5.9

Freeform Pools:

• Calculate the volume of each section using the appropriate formula.

• Add the volumes of all sections to get the total volume.

Once you’ve calculated the volume of your pool, you’ll need to make a few potential adjustments.

Step 3: Adjust for Irregular Depths and Shapes

If your pool has varying depths or complex shapes, you need to adjust your calculations. For pools with a sloping bottom, it's best to break the pool into sections based on consistent depths. For example, that would mean separating the shallow end, the deep end, and any gradual slope in between. Then you can calculate the volume of each section individually, treating each as a simple shape like a rectangle, trapezoid, or cylinder, depending on the design. Once you have the volume for each section, add them together to find the total pool volume.

If your pool includes features like rounded edges, steps, or irregular extensions, you’ll want to estimate the volume of those areas separately and add that to your main calculation. 

Taking the time to adjust for these details makes sure you get a much more precise estimate, which is especially important for tasks like balancing chemicals or ordering a pool cover.

Step 4: Double-Check Your Calculations

It’s really important to get this correct. So, for accuracy, it's crucial to double-check your measurements and calculations. You know what they say in construction, measure twice and cut once? It’s the same thing for pools. Small errors in measurement can lead to really large discrepancies in the volume.

Additional Tips

Since measuring your pool volume for things like chemicals is a big deal, there are a few other ways to calculate pool gallons:

1. Use Online Calculators: You can always use a pool volume calculator, which can simplify the process. You just input your pool's dimensions, and they will compute the volume for you.

2. Professional Assistance: If you're really unsure about your calculations or have an irregularly shaped pool, it might be a good idea to consult a pool professional. They have the expertise and tools to provide precise measurements.

3. Regular Checks: It’s always a good idea to recalculate your pool’s volume if you make any changes to its shape, size, or depth. Keeping updated measurements will ensure that your pool maintenance will be much smoother. 

How to calculate pool gallons isn’t as difficult as it might seem at first glance. With careful measurements and some simple calculations, you should be all set. u This valuable information will allow you to effectively manage its chemical balance, ensuring a safe and enjoyable swimming experience. For all of your pool filters, cleaning, lighting needs, and more, don’t forget to turn to the experts at Vita Pool Supply. environment. 

Frequently Asked Questions 

How can I tell how many gallons my pool is?

To determine the volume of your pool in gallons, you must first calculate the cubic footage based on its shape and then multiply that number by a specific constant. Use the following steps and formulas to find an accurate estimate.

1. Determine Your Average Depth

Before calculating volume, you need the average depth of the pool. 

Formula: (Shallow End Depth + Deep End Depth) ÷ 2 = Average Depth

2. Calculate Based on Pool Shape

Use the formula that corresponds to the shape of your pool. In these formulas, the multipliers (7.5, 5.9, and 6.7) convert cubic feet into gallons.

• Rectangular or Square Pools: Length x Width x Average Depth x 7.5 = Total Gallons
• Round/Circular Pools: Diameter x Diameter x Average Depth x 5.9 = Total Gallons
• Oval Pools: Longest Length x Widest Width x Average Depth x 6.7 = Total Gallons
• Kidney or Irregular Shapes: (Widest Width + Narrowest Width) x Length x 0.45 x Average Depth x 7.5 = Total Gallons

How many gallons is a 16x32 pool?

A standard 16x32 foot rectangular pool typically holds between 17,200 and 22,000 gallons of water. The exact volume depends primarily on the pool's average depth.

How big is a 20,000 gallon pool?

A 20,000-gallon pool is considered a medium-to-large residential swimming pool. While the exact footprint depends on the shape and depth profile, this volume typically translates to a surface area of approximately 500 to 600 square feet. 

How big is a 50,000 gallon pool?

A 50,000-gallon pool is considered a large-scale residential or a standard commercial-sized pool. To put its size in perspective, it is nearly three times the size of an average backyard pool, which typically holds between 15,000 and 20,000 gallons. 

How many gallons are in a residential pool? 

The average residential swimming pool holds between 15,000 and 20,000 gallons of water. However, the total volume depends significantly on the pool's dimensions, shape, and depth profile.

Average Capacity by Pool Size

• Small Pools (approx. 12' x 24'): 8,000 to 12,000 gallons.
• Medium Pools (approx. 16' x 32'): 15,000 to 22,000 gallons.
• Large Pools (approx. 20' x 40'): 30,000 to 40,000+ gallons.
• Above-Ground Pools: Typically range from 5,000 to 15,000 gallons depending on diameter (usually 15' to 27').