How Heavy is a Full Inflatable Hot Tub?

Ever thought an inflatable spa would be as light as your kid’s paddling pool? Not quite. Once you add water and people, these tubs can get surprisingly heavy — we’re talking the weight of a small car in some cases.

The short answer? A full inflatable hot tub can weigh anywhere between 400–1,200 kg depending on size, shape, and how many people pile in.

Stick around to find out exactly what makes them so heavy, what that means for your decking or patio, and how to make sure your spa is safe to use at home.

Understanding the Weight of an Inflatable Hot Tub

The Inflatable Hot Tub's Dry Weight (Empty)

When empty, inflatable hot tubs are surprisingly manageable. Most weigh between 20–50 kg, which means two people can easily shift them around the garden before filling.

The Weight of the Water

Here’s where things get serious. Water is heavy — 1 litre = 1 kg. A small 500-litre spa instantly adds 500 kg before anyone even dips a toe in.

The Weight of the Occupants

Now add people. Two average adults at around 80 kg each add another 160 kg. Got kids, friends, or a full house? That number climbs fast.

The Total Filled Weight (Empty + Water + Occupants)

Put it all together and even a modest inflatable spa can weigh 400–450 kg. Larger models designed for six or more people? They can tip over 1,000 kg — more than a grand piano.

Factors That Influence the Total Weight

Size and Capacity (2-person vs. 4-person vs. 6-person)

The bigger the tub, the heavier it gets. A cosy 2–4 person spa is on the lighter side, but a family-sized 6+ seater can be well over 900 kg when full.

Shape (Round vs. Square)

Round tubs spread weight more evenly, while square tubs may put more pressure on certain areas — something to keep in mind if you’re using decking.

Hot Tub Material and Construction

Premium tubs with reinforced walls or extra padding weigh a little more empty, but they’re sturdier, hold heat better, and usually last longer.

Added Accessories (Covers, Steps, etc.)

Covers, steps, and drink trays don’t add much individually, but every kilo counts. The real benefit? A good insulated cover keeps heat in, meaning less energy used to reheat the water.

Practical Considerations for Hot Tub Placement

Understanding Pounds Per Square Foot (PSF)

It’s not just about the total weight — it’s about how that weight presses down on the surface. This is measured in pounds per square foot (PSF), and it’s crucial for working out if your patio or decking can cope.

How to Calculate the PSF for Your Hot Tub

Here’s the simple formula: take the total filled weight (tub + water + people) and divide it by the surface area of the hot tub’s base. That’s your PSF. Compare it against what your surface is designed to handle.

Why Proper Surface Support is Crucial

Get this wrong, and you could end up with sagging decking, cracked paving, or worse. Always check the limits of your surface before you fill.

Suitable Surfaces for an Inflatable Hot Tub

Concrete Patios and Slabs

Concrete is the gold standard. It’s flat, strong, and more than capable of holding a fully loaded inflatable spa.

Wooden Decks (When is it Safe?)

Decking is trickier. A new, reinforced deck might hold a smaller tub, but older decking may struggle with the weight. Always double-check the structure before setting up.

Other Surfaces to Consider (or Avoid)

Grass, gravel, and uneven ground are a big no. Not only do they put stress on the tub itself, but they can also sink or shift under the weight.

Final Thoughts

Inflatable spas might look light and portable, but once filled, they pack a serious punch in terms of weight. Between the water, the tub itself, and everyone enjoying a soak, you’re often looking at hundreds of kilos pressing down on your surface.

By understanding the numbers and thinking about where to place it, you’ll avoid costly mistakes and keep your family safe. Then, all that’s left to do is pour yourself a drink, turn on the bubbles, and enjoy that well-earned relaxation.