How Many Gallons Does a Hot Tub Need? With Online Calculator

Are you new to hot tubs and concerned about water usage? Or you want to know how much a hot tub weighs. So you can find out if your patio or deck can support it. It is good to know the exact quantity of water that will fill your hot tub for these situations.

How many gallons does a hot tub need:

Hot tubs vary in size and the number of people they are designed for. A small hot tub is designed for two to three-person and can hold up to 300 gallons. Larger hot tubs for seven persons can hold at least 675 gallons of water.

Several factors determine the number of gallons a hot tub needs. In this blog post, I will explore these factors to help you better understand and know how to determine how much water a hot tub need.

How Many Gallons Does a Hot Tub Need?

Hot tubs vary in the amount of water needed to fill them for smooth function and give the optimum experience. The number of gallons required depends on the hot tub's dimensions, shape, depth, and size. There are different ways to calculate the water carrying capacity of a hot tub in addition to these factors.

I will now look at the details on the number of gallons a hot tub needs to work optimally and deliver the best massage experience.

Factors that Determine the Number of Gallons a Hot Tub Need

Before heading to the details on calculating the capacity of a hot tub, it is important to understand the different factors that influence this:

1. Dimensions

This is a vital factor that determines the water capacity of every hot tub. Dimensions comprise the tub's shape, seating capacity, size of seats, number of jets, height, and depth of the hot tub. All of these play a key role in determining the capacity of the tub.

A larger hot tub will hold more water compared to a smaller hot tub. Therefore, it is important to consider all the hot tub dimensions when determining the number of gallons to fill it.

2. Shape

Hot tubs come in different shapes. Depending on your requirements, there are triangle, oval, circle, rectangle, or square-shaped hot tubs. The shape also determines the size of the hot tub and its seating capacity.

In general, square and rectangle-shaped tubs make the best use of the space. They are generally larger, and can hold more water than other shapes. Those shapes do require a thicker and need a stronger construction, and are often heavier. Shapes like triangles and circles will require less water to function smoothly. Round hot tubs require a less sturdy construction and are often lighter. That is why inflatable hot tubs are round.

3. Depth

Depth of the hot tub is also an important factor to consider when determining the water capacity of the tub. As mentioned earlier, a deeper hot tub will need more water to get filled and function smoothly. Also, a small hot tub with the depth of a large-sized hot tub will hold more water.

It is important to note that, generally, hot tubs don't vary much in their depth. Regardless of their size, the depth range for hot tubs is usually between 30 to 40 inches.

4. Size

The last factor to consider is the size of the hot tub. The footprint and length of the hot tub influence the person count of the tub. Large hot tubs can accommodate more users but need significantly more water.

In most hot tubs, the user capacity of a hot tub is fixed. For each person, there is a seat. Only with more simple (mostly round) models are there no fixed seat positions. If people sit closer together, the hot tub can fit more persons.

How to Figure Out How Many Gallons a Hot Tub Need

There are several methods to find out how many gallons a hot tub needs. The easiest is to check the user manual or use google. Alternatively, you can use the dimensions of the hot tub to calculate how much water it needs. This is the dimension calculation method. Another method is to use the time it takes to fill the hot tub and calculate the amount of water this way. This is the time-tested method.

I will first look into the dimension calculation and the time-tested method in more detail. Both methods involve some simple math and have proven to be effective in estimating the water capacity of different hot tubs.

1. Dimension Calculation Method

This is an effective calculation to use in estimating the number of gallons a hot tub needs. Here are the steps you can use to get a good estimation:

• Step 1. Internal dimension: Determine the internal dimensions of the tub by taking measurements carefully. You need the width, length, and height. In some cases, the height is difficult to measure as some parts are deeper than others. Try to use a sort of average height.
• Step 2. Calculation step: Subtract 4 inches from the height as you will not fill the hot tub until the edge. Then multiple this height with the width and length. This is for square or rectangular hot tubs. I will show later what to do for other shapes.
• Step 3. To compensate for seats: If the hot tub has seats, divide this number by 621. If there are seats, divide it by 864. The answer you get in both cases is an estimate of the number of gallons that the hot tub needs.

How to calculate the volume in step 2 depends on the shape of the hot tub:

• Rectangular or Square Shaped hot tub: For these shapes, you'll need to measure the depth, length, and width of the hot tub in inches. Subtract the height with 4 inches. Multiply this number with the width and height.
• Round hot tub: Calculating the dimensions of circular hot tubs is different compared to rectangular or square-shaped ones. To calculate the volume, first, measure the width going through the center of the hot tub in inches. Then measure the depth in inches. Multiply both numbers and multiply this with 2. This number can then be used in step 3.
• Portable/inflatable hot tub: Most portable hot tubs are round and do not have seats. To calculate the volume, first, measure the width going through the center of the hot tub in inches. Then measure the depth in inches. Multiply both numbers and multiply this with 2. This number can then be used in step 3.

2. Time Tested Method

This is the most accurate method to determine the number of gallons a hot tub needs. All you need to do is use a hose and determine the time it takes for the hot tub to fill. However, for accurate results, here are a few steps to follow:

• Step 1. Fill a 5-gallon bucket with water: Fill a 5-gallon bucket with water and note the time in minutes it takes. We use a 5-gallon bucket as an example. You can use any size bucket.
• Step 2. Measure the time to fill the hot top: Use a stopwatch to measure the time in minutes it takes to fill the hot tub. Ensure that you set the tap similar to when you filled the bucket.
• Step 3. Calculate the time for 1 gallon: Divide the time in minutes it took to fill the bucket by the size of the bucket. In our example, it means you have to divide it by 5. The result is the time it takes to add 1-gallon water.
• Step 4. Calculate the number of gallons: Divide the total time it takes to fill the hot tub by the time it took to fill 1 gallon. This will give you the number of gallons the hot tub needs.

Additional Methods

The two methods mentioned above are more complex and time-consuming to determine the number of gallons a hot tub needs. However, there are other methods that you can use:

• Use Google: Google is a useful tool to help you determine the number of gallons your hot tub need. All you need is the exact model of the hot tub to make things a lot easier for you. You can get the model of the hot tub by removing its panel. With this, you can search for the number of gallons it needs and be sure of getting useful results.
• Check the user Manual: Most hot tubs come with a user manual from the manufacturer. Here, you can find all the details you need, including the number of hot tub gallons.
• Contact the Manufacturer: If you have searched google and checked the user manual without getting any result, you can contact the manufacturer. This will give you firsthand information that you can rely on. The manufacture will give you authentic information about your hot tub. Check the manufacturers website for contact details.
• Check with a Local Dealer: A local dealer may be easier to reach compared to the manufacturer. You can also get authentic information from the local dealer. This includes the number of gallons required to fill the hot tub.

How many gallons in a 2 person hot tub

Generally, a 2 person hot tub contains between 150 gallons to 230 gallons of water. The exact amount depends on the type of hot tub, and if it contains seats or not. A hot tub with seats mostly has less water than one without.

How many gallons in a 3 person hot tub

Generally, a 3 person hot tub contains between 200 gallons to 300 gallons of water. The exact amount depends on the type of hot tub, and if it contains seats or not. A hot tub with seats mostly has less water than one without.

How many gallons in a 4 person hot tub

Generally, a 4 person hot tub contains between 250 gallons to 350 gallons of water. The exact amount depends on the type of hot tub, and if it contains seats or not. A hot tub with seats mostly has less water than one without.

How many gallons in a 5 person hot tub

Generally, a 5 person hot tub contains between 300 gallons to 400 gallons of water. The exact amount depends on the type of hot tub, and if it contains seats or not. A hot tub with seats mostly has less water than one without.

How many gallons in a 6 person hot tub

Generally, a 6 person hot tub contains between 300 gallons to 500 gallons of water. The exact amount depends on the type of hot tub, and if it contains seats or not. A hot tub with seats mostly has less water than one without.

How many gallons in a 8 person hot tub

Generally, an 8 person hot tub contains 600 gallons or more. The exact amount depends on the type of hot tub, and if it contains seats or not. A hot tub with seats mostly has less water than one without.