Average Hot Tub Weights with Example Sizes

A hot tub is a luxury item and so people often purchase the largest size they can afford, but if you don’t manage properly your spa might become overstuffed. This article will show some examples of what kind of weights are normal for different sizes of spas.

The “how heavy is a hot tub in kg” is a question that has no answer. There are many different sizes of hot tubs, which makes it difficult to find an average weight. This article will provide you with the average weights for different size hot tubs.

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A backyard hot tub might be the ideal at-home retreat for a soothing bath. However, before you install the tub, you must evaluate its weight and dimensions to choose the best location where its weight can be sustained adequately. 

Depending on the size and construction material, hot tubs may weigh anywhere from under 100 pounds to over 1000 pounds. Before water is added, a hot tub weighs roughly 500 pounds on average. When full, the same 500-pound hot tub will weigh close to 3000 pounds. 

We’ll look at how the weight of a hot tub, as well as the weight of the water and people using it, impacts installation in this post. We’ll also go through the different sizes of hot tubs now on the market so you know what to anticipate if you’re thinking about getting one. 


Contents Table of Contents

  • There Is No Such Thing As A Hot Tub Weight 
  • What is the best kind of foundation for a hot tub? 
  • What Is the Weight of Water in a Hot Tub?  
  • Is a Crane Required for Hot Tub Installation?
  • Final Thoughts


There Is No Such Thing As A Hot Tub Weight 

Different variables influence the weight of hot tubs, therefore let’s look at why there are differences: 

Weight Is Affected by the Hot Tub’s Composition

The material chosen in the building of a hot tub will affect its quality, price, and weight. The majority of hot tubs are built of one or more materials. 

Here are a few instances of how various materials effect weight. These weights are based on a four-person midsize hot tub; the weight will vary depending on the tub size selected.

Material Types Without Water, Weight
Plastic Soft 100 lb. or less
Plastic Molded 300 lb.
Acrylic  450 lb.
Steel, stainless 250 lb.
Fiberglass 330 lb.
Concrete 400 lb.


The weight of a hot tub is naturally influenced by its size. Customers may choose from a variety of forms and sizes in hot tubs. 


Most hot tubs are available in three sizes: small, medium, and big. There are two things that influence this: 

  • The maximum number of people it can accommodate
  • The tub’s actual measurements 

Number of Residents

The following is a breakdown of how hot tubs sizes correspond with its recommended maximum Number of Residents:

  • 2 to 4 persons in a small hot tub
  • 5 to 7 persons in a midsize hot tub
  • 8 persons or more in a large hot tub

Dimensions of a Spa

By examining the various measurements of a hot tub, you may assess if you have enough room inside or outside your house to install one. The average weight of various sizes of hot tubs, excluding the plastic blow-up versions, is shown in the table below. 

  Length Width Empty Weight Average
Small 5’5”-7’ 5’4”-6’8” 300-500 pound
Midsize 6’6”-7’10” 6’4-7’9” 600-700 pounds
Large 7’-9’ 7-9’ 800-1000 pound

Remember to include the water weight.

After you’ve decided on the size and material of your hot tub, be sure the location you’re going to put it in is strong enough to support the weight of the water. In a moment, we’ll go into water weight in more depth. 

What is the best kind of foundation for a hot tub? 

The Different Types of Hot Tub Foundations

We know that full hot tubs may weigh over 3000 pounds. This does not take into account the weight of the people in the hot tub. You must account for the weight of the four individuals who will be sitting in a four-person hot tub. 

The hot tub unit will need some kind of support in order to avoid sinking into the ground or damaging a foundation that is not strong enough to sustain it. 


When it comes to supporting the weight of a hot tub, a concrete slab may be the best option. 

The concrete should be at least four inches thick, with a six-inch foundation material underneath it. 

If you’re adding anything other than a hot tub to the slab, let your contractor know in case the concrete has to be strengthened. 

Brick Pavers

Like concrete, Brick Pavers are another good option to support a hot tub. The pavers also need a six-inch base material under them to help give support. 

The following are examples of general foundation materials that may be used:

  • Sand
  • gravel pea
  • Crushed stone

Without the paver bricks, the hot tub may sometimes be built straight on the gravel.


When concrete is not an option, most hot tubs may be supported by a deck. A hot tub may be supported on most decks that are less than a couple of feet from the ground. 

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However, when you raise the height of the deck, it may become unstable. The higher the deck is constructed, the more reinforcements are required. To maintain a secure deck space for a full hot tub, call a specialist. 

Spa Pad

Spa pads are made out of interlocking plastic pieces that support a hot tub. The majority of them may be found at stores that sell hot tubs. They’re designed to hold at least 100 pounds per square foot. 

What Is the Weight of Water in a Hot Tub?  

Water Weight Calculation

As we’ve seen, the weight of a hot tub varies depending on its size and the materials used to construct it. Let’s see how that weight changes with the addition of water. This is critical owing to the significant weight gain after filling the hot tub with water. 

When calculating how much support the hot tub will need, the ultimate Water and Weight must be taken into account. 

A gallon of water weighs 8.34 pounds. This explains why adding water to a hot tub increases its weight dramatically. Of course, the greater the hot tub’s size, the more water it will take to fill it, and the heavier it will be. The chart below illustrates how much a hot tub’s weight rises when it is filled with water. 

Material Types Without Water, Weight Water and Weight
Plastic Soft 100 lb. or less 2200 lb.
Plastic Molded 300 lb. 2800 lb.
Acrylic  450 lb.  3000 lb.
Steel, stainless 250 lb. 2800 lb.
Fiberglass 330 lb. 2850 lb.
Concrete 400 lb. 2900 lb.

Is a Crane Required for Hot Tub Installation?

A crane is often not necessary to construct a hot tub in a backyard. Companies who sell and install hot tubs utilize a hot tub cart to transport the tub to the installation location. 

A crane may be required in certain cases when a hot tub trolley is not acceptable. A crane may be required in houses with moist soil that would cause the cart to sink or residences with insufficient room to transport the cart to a backyard. In this case, a crane service may be engaged, which will normally increase the cost of the installation. 

Final Thoughts

Hot tubs come in a variety of forms and sizes. The weight of each hot tub is determined by the material used, the amount of water supplied, the weight of the passengers, and the size of the unit. Once you’ve decided on the size of hot tub you want, you may look into whether or not it can be installed. 

As you can see, there are several factors to consider when considering whether or not to install a hot tub. It may be devastating for those who buy a hot tub without first considering its size and weight. It is important to have a competent installation assess the area where you wish to put a hot tub. This will save you time and money in the long run. 


The “hot tub weight per square foot” is an average of the weights for hot tubs with a given size. The example sizes are 6×4, 8×6 and 10×8.

  • how much does a 6-person hot tub weigh empty
  • 4-person hot tub weight
  • hot tub dimensions and weight
  • how much does a hot tub weigh with water
  • 8 person hot tub weight
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