Round Hot Tub

Why choose a round hot tub?

Round is the traditional shape for inflatable hot tubs, and there are good reasons for it. An air-filled wall holds its shape best as a circle, because the pressure is spread evenly with no corners to bulge or crease. That makes the hot tub firmer to lean against and kinder to the seams.

The shape also changes how a soak feels. Everyone faces the centre, so conversation is easier than in a square hot tub where two people end up shoulder to shoulder along a side. Round lids have no corners to seal either, so they sit flat and keep heat in well, which matters because the open water surface is where a hot tub loses most of its warmth.

Round vs square: which fits your garden?

A circle takes up less floor area than a square of the same width. A 180cm round hot tub covers about 2.54m², while a 180cm square one covers 3.24m², so the circular version uses roughly a fifth less of your patio. That leaves room for steps, a side table or a path around it.

	Round	Square
Seating	Everyone faces the middle	Two to a side, corner seats
Footprint at 180cm wide	About 2.54m²	About 3.24m²
Wall strength (inflatable)	Even pressure all round	Corners take extra strain
Best spot	Open patio, middle of a deck, lawn edge	Tucked into a corner or against a wall
Lid fit	No corners to seal	Corners can lift in wind

If your space is a corner between two fences, a square hot tub may use it better. For an open patio, the circle usually wins.

Round inflatable hot tub sizes

Box sizes are quoted as the outside diameter, and an inflatable wall is thick. The Lay-Z-Spa St Lucia is 170cm across but only 124cm inside, so always check the interior size or the seat count. As a rough guide:

• 156-170cm: two to three adults, or two adults and a child. Good for small gardens, balconies with enough load capacity, and couples.
• 180cm: the most common size, comfortable for four.
• 190-200cm: four to six, the usual family choice.
• 208cm and up: six to eight for regular gatherings.

Manufacturer seat counts are the maximum, not the comfortable number. Knock one off the figure if you want room to stretch out.

Round hot tubs compared

These are the circular hot tubs from our range with figures taken from each listing. Litres are left blank where the maker doesn't give a reliable figure.

Model	Outside diameter	Seats	Water	Jets	Wall
Wave Tahoe	156cm	4-6	-	90 AquaJets	PU foam core
Lay-Z-Spa St Lucia	170cm	2-3	605L	110	3-layer PVC, I-beam
Lay-Z-Spa Aruba Signature	170cm	3	-	110	3-layer PVC
Lay-Z-Spa Carrara	170cm	4-6	-	140	ThermaCore foam
Lay-Z-Spa Boracay	180cm	4	669L	120	3-layer PVC
Lay-Z-Spa Helsinki AirJet Plus	180cm	up to 7	-	180	Drop stitch
Coleman Palm Springs	196cm	4-6	-	140	3-layer PVC
Lay-Z-Spa Palm Springs AirJet 6	196cm	4-6	-	140	PVC
Lay-Z-Spa New York	196cm	6	-	140	TriTech 3-layer
Aoxun 208cm	208cm	4	1,000L	130	3-layer PVC
Intex PureSpa Bubble 8	236cm	8	1,340L	170	Fiber-Tech beams

Jet counts on air-bubble spas are the number of holes in the floor ring rather than separate massage nozzles, so 110 and 140 feel similar. The bigger differences are wall type, insulation and seat count.

Wall types: PVC, drop stitch and foam

Standard 3-layer PVC

Most budget inflatable hot tubs use a laminated PVC wall held in shape by internal beams (I-beam, Fiber-Tech or MaxHold). They are light, pack small and are the cheapest to buy, which is why so many of our hot tubs under £300 take this form. The walls flex a little when you lean back.

Drop stitch

Drop stitch walls have thousands of threads linking the inner and outer skins, so they inflate much firmer and sit more upright. The Lay-Z-Spa Helsinki uses it, and it is the step up most buyers notice straight away.

Foam wall

Foam-wall tubs such as the Wave Tahoe and Lay-Z-Spa Carrara swap air for an insulated foam core. Wave claims 60% better heat retention than standard PVC and Lay-Z-Spa says 60% more efficient, so they cost less to keep warm through a British winter, though they are heavier and take more space to store.

Heating, power and running

Nearly every inflatable hot tub is plug and play: it runs from a standard 13A socket through the RCD built into its plug or pump. The heaters are around 1.5-2.2kW, which is why warming the water is slow. The St Lucia quotes 1.5-2°C an hour, the 1,340-litre Intex 0.8-1.5°C, and Lay-Z-Spa allows 12-24 hours for the Boracay's first heat from cold.

• Plug straight into an outdoor weatherproof socket. Makers tell you not to use an extension lead, and Electrical Safety First says all outdoor electrics should be RCD protected.
• Keep the lid on and clipped whenever the hot tub isn't in use. A thermal lid is the biggest single saving on running time.
• Use the timer to have it hot when you want it rather than heating all day.
• A ground sheet plus insulated floor tiles stops heat leaking into a cold patio.

Where to put your hot tub

Water weighs 1kg a litre, so a 605-litre tub weighs well over half a tonne before anyone gets in, and the Intex 8 person holds 1,340 litres. Choose a flat, level, solid base such as paving slabs, a concrete pad or a deck rated for the load. Lawn is a poor choice: it sinks unevenly and the grass dies underneath.

• Allow a clear margin around the tub for getting in and out and reaching the pump. Aoxun recommends 250 x 250cm of floor for its 208cm model.
• Remove stones and sharp edges, then lay the ground sheet before inflating.
• Think about the hose route for filling and where the water will drain.
• Shelter from wind helps keep heat in. A fence or screen on the windward side makes a noticeable difference.

Want it to blend into the garden? Our wood effect hot tubs include several circular models with timber-look walls.

Using it through the winter

Many Lay-Z-Spa and Coleman spas have Freeze Shield, which turns the heater on automatically when the water drops to 6°C and off again at 10°C. That protects the pipes, but it isn't a reason to leave a hot tub idle and unheated in a hard frost. If you won't use it for weeks, drain, dry and store it. Foam-wall and drop stitch tubs, and a good lid, make year-round use far more practical.

Safety and water care

RoSPA advises no under-fives in a hot tub, sessions of about 15 minutes, a solid lockable cover and constant supervision of children near open water. It also suggests checking that a hot tub meets BS EN 17125:2018 and BS EN 60335-2-60.

Warm, still water can grow bacteria, including legionella. Keep the sanitiser level up, change the filter cartridges as the manual says and replace the water regularly. The HSE guidance on spa pools explains the risk, and applies in full if you let the tub out as part of a holiday let or business.

Which round hot tub should you buy?

• Couples and small gardens: a 170cm tub like the St Lucia, or browse all our 2 person hot tubs.
• Families of four: a 180cm model such as the Boracay, or the drop stitch Helsinki for firmer walls.
• Groups and parties: 196cm and up, from the Palm Springs to the Intex PureSpa 8. See more 6 person inflatable hot tubs.
• Year-round use: a foam-wall Wave Tahoe or Lay-Z-Spa Carrara.
• Tight budget: start with our cheap hot tubs and the best inflatable hot tubs for the money.

Round hot tub FAQs

What size is a round hot tub?

Inflatable circular spas usually measure 156-236cm across the outside and about 65-73cm high. The inside is much smaller because of the wall: a 170cm St Lucia is 124cm inside.

How many people fit in a round hot tub?

Roughly two to three at 170cm, four at 180cm, four to six at around 196cm and up to eight at 236cm. The quoted figure is a maximum, so one fewer is more comfortable.

Are round hot tubs better than square ones?

For most patios, yes: they take up less floor area for the same width, everyone faces each other and inflatable walls hold their shape better. A square model suits a corner better.

How long does it take to heat?

Expect 1-2°C an hour, so a first fill from cold can take 12-24 hours. Keeping the lid on and the water warm between sessions is quicker and cheaper than reheating from cold.

Can I plug it into a normal socket?

Yes, inflatable models run on a 13A plug with a built-in RCD. Use an outdoor weatherproof socket and don't run it through an extension lead.

How heavy is it when full?

Count 1kg for every litre of water plus the people in it. A 669-litre 180cm tub weighs about 670kg in water alone and close to a tonne with four adults in, so a deck or balcony must be rated for it.

Can I leave it up all winter?

You can if you keep it heated, lidded and use Freeze Shield where fitted. If it will sit unused, draining and storing it dry is safer for the liner and pump.

What should go underneath?

A level, solid surface, then the ground sheet supplied and insulated floor tiles. They protect the base from stones and cut heat loss into the ground.