How Many Gallons Does a Hot Tub Hold?

Find out how many gallons your hot tub can hold using these time-tested methods with tools you can easily find at home. Follow the steps in this article and get results in no time.

One of the questions people fail to ask when buying a hot tub is how many gallons of water does a hot tub hold? Chances are they won’t figure it out until they have to sanitize the hot tub or get their first water bill after installing one in their house. Let’s find out how it’s done in this article.

How do I figure out how many gallons my hot tub is?

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There are many ways to figure out how many gallons in a hot tub there are but the 2 most common ways of doing it are the time-filled method and the dimensions calculation method. These 2 methods will give you an approximate amount which may vary slightly depending on certain situations, e.g. water pressure or number of seats. 

The Timed Fill Method

With timed fill you’re going to take note how long it would take to fill your hot tub with water and then do the same for a 5-gallon bucket. For consistency, use the same diameter for your hose and choose a specific time of the day where water pressure is stable.

How Many Gallons Does a Hot Tub Hold? 1

It usually only takes several minutes to fill the hot tub. Use a regular stopwatch to record how long it took to fill it up. Get the minutes, multiply it by 60 and add the seconds. Do the same for your 5-gallon bucket.

Next, divide the number of seconds to fill the hot tub by the number of seconds it took to fill the 5-gallon bucket. Multiply the result by 5 and you get the total number of gallons your hot tub can hold.

The Dimension Calculation Method

This method is much quicker since you don’t have to wait and you don’t need to actually fill the hot tub with water. You just have to measure certain dimensions based on its shape. Hot tubs are typically square or round but may also come in different shapes.

With a square tub, you’re going to get the width, length, and depth in inches and get the product of all three. Next, you need to convert the result (cubic inches) to cubic feet by dividing it by 1,728. You need to multiply again, by either 2.4 if your hot tub has seats, or 4.8 if it has none. Now you know how many gallons of water are in a hot tub using the dimensions calculation method

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For a round hot tub, you only need the diameter and depth in inches. Make sure your tape measure runs straight across the center of your hot tub when getting the diameter. Multiply this by the depth of your hot tub and divide it by 1,728. Multiply the result by 2.4 if it has seats or 4.8 if it has none like you would for a square hot tub.

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Takeaways: Timed fill requires filling up your hot tub with water (slow approach) but dimension calculation only needs measuring your hot tub’s length, width, and depth for a square hot tub, or diameter and depth for a round tub (fast, get results instantly). Both methods can be used to get the approximate number of gallons your hot tub can hold.

The Factors to Determine the Hot Tub Capacity

How much water your hot tub can hold will depend on certain factors. These are:

  • Size of the hot tub
  • Depth of the hot tub
  • Shape of the hot tub

A typical small hot tub for 2 persons can hold around 150-220 gallons, about 200-300 gallons in a hot tub for 3 persons (medium), and about 320-475 gallons of water in a hot tub for 6 persons (large). Hot tubs can also vary in depth. The deeper it gets the more water it can hold.

Finally, the shape will have an impact on your hot tub water capacity. For instance, a square hot tub can take up more water compared to a round one of the same length/diameter.

Takeaways: To determine how much water your hot tub can hold, consider its size, depth, and shape.You can make quick estimates as to how many gallons of water in a hot tub is needed to fill it up based on a given criteria. If you want to be sure, you can use the two methods mentioned in the previous section.


Anyone with the right tools can determine how much water a hot tub can hold. It’s not rocket science. You simply choose your own method, follow the steps and get results within minutes.