how many gallons of water in a hot tub

How to Calculate How Many Gallons of Water Your Hot Tub Holds

You could be on the hunt for your first hot tub, or you could be considering installing a hot tub on your patio or deck, and you want to know if it’ll support the weight of the hot tub when it’s full.

You could also be trying to calculate water consumption, and this can lead you to wonder how many gallons of water your specific hot tub can hold.

Unfortunately, there are several variables that come into play here, and it can be challenging to narrow down an exact answer.

The short answer to how many gallons can your hot tub hold is that it depends on the hot tub’s shape, size, and maximum capacity.

We’re going to break down how much the average hot tub holds by capacity, and we’re also going to give you several tips and formulas to help you figure out a more concrete answer so you know if your space will support the weight.

A Rough Estimate on How Many Gallons a Hot Tub Holds by Capacity

As we said, the exact amount of gallons of water your hot tub holds comes down to different factors but you can get a rough estimate just by knowing the capacity. This will give you a starting point to narrow down your calculations.

Two-Person Capacity

If you’re just getting your first hot tub, you may want to go smaller and get one that will comfortably hold two people. You’ll get plenty of room to sit and relax at the end of a tough day, and it’s a slightly lighter option. Generally, a two-person hot tub will hold anywhere from 150 to 220 gallons of water when it’s full.

Three-Person Capacity

If a two-person hot tub is slightly too small for your wants, you can upgrade it slightly with a three-person hot tub. The number of gallons you’ll need to fill this size hot tub will range from 200 to 300 gallons. The less seating area you have, the more gallons of water will fit into the hot tub because you’ll have more open space.

Six-Person Capacity

Anyone who wants to spend the weekends entertaining family and friends in the hot tub will need to look at a slightly larger model at a six-person capacity. This larger hot tub can easily accommodate between 320 to 475 gallons of water.

You may notice that the amount it holds tends to get wider as the size goes up, and this is because you’re usually getting into more luxury hot tubs at this level that use features to take up room.

Eight-Person Capacity

The average eight-person hot tub can hold anywhere from 615 to 675 gallons of water at any given time. Also, the average weight for this hot tub when you fill it up goes up to an impressive 7,800 pounds, not including any people who get in. At this weight, it could be dangerous to install it on your deck without a huge amount of support and reinforcements.

Six Ways to Determine How Many Gallons Your Hot Tub Will Hold

There are four methods to find out how many gallons your hot tub holds that will require research on your part, and two of the methods are math-based. They could all help you get a closer estimate for your specific model.

Check the Manual

The first thing you want to do is check the manual for your specific hot tub because it’ll tell you everything you need to know about it. If you don’t have it because you lost it or because you bought this hot tub used and didn’t have one, you can do a little research and try to track one down. It’ll list the exact amount of gallons it holds.

Perform a Google Search

Before you start your search, remove the panel from the side of your hot tub in the spot that allows you to access the inside of the unit.

Look around until you find the hot tub’s model or serial number and take note of it by writing it down or snapping a picture. This number is what you’ll use to track down the specific information about your hot tub.

Next, start by doing a generic search in Google like hot tub gallons or hot tub capacity. Then, put in the model or serial numbers you found inside your hot tub. This may take a few tries, but you might be able to track down a digital manual for your model or a website that specializes in your hot tub.

Give the Dealership a Call

Maybe you bought your hot tub from a dealership instead of from a stranger or family member. If so, give the dealership a call and ask them to help you figure out how many gallons your hot tub holds. Almost anyone in the store should know or be able to look up this information for you unless they discontinued the model.

Call the Hot Tub’s Manufacturer

If you exhausted all of your options and you’re still not sure how many gallons it can hold, call the company that manufactured your specific hot tub. They should have a website where you can find their phone number and make sure you ask them where you can find a copy of the manual, so you have it on hand if you need it in the future.

Dimension Calculation

For this method, you’ll need a tape measure, calculator or pen and paper, and some patience. The general steps are to measure the hot tub’s external dimensions, multiply, divide, and multiply again. The method varies slightly depending on whether you have a round or square hot tub.

Square Hot Tub Calculation Method

To calculate the gallons in a standard square hot tub, you’ll have to do the following:

  • Get out the tape measure and check the depth, length, and width of the hot tub
  • Write down each number in inches
  • Multiply the length by width by depth
  • Get your result and divide it by 1,728
  • Multiply this result again. If your hot tub has seats, you’ll multiply your answer by 2.4, and if your hot tub doesn’t have seats, multiply it by 4.8

The total you end up with is the total capacity of your hot tub in gallons.

Round Hot Tub Calculation Method

If you have a round hot tub, you’ll use the following formula to calculate your hot tub’s total gallon capacity:

  • Measure the diameter of the tub by centering your tape measure straight across the middle
  • Find the depth and record both the diameter and the depth
  • Multiply the diameter by the depth
  • Divide the answer by 1,728
  • Multiply the answer by 2.4 if the hot tub has seats or 4.8 if it doesn’t have seats

The number you get is the total number of gallons your hot tub can hold.

Bottom Line

It’s important that you know exactly how many gallons your hot tub holds, especially if you want to install it on a raised deck or patio.

Since the number will vary based on a few factors, you can now use the search tips, capacity estimates, and calculation methods to find how many gallons your hot tub holds.

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