Inflatable hot tub running costs: what they really cost to run
The purchase price of an inflatable hot tub is only half the story; the running cost is the part that surprises people. We metered every tub on test over a month to find out what they really cost to run, and the answer is between about £34 and £48 a month, with insulation moving that figure more than the tub itself. Here is what they cost and how to cut the bill.
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What an inflatable hot tub costs to run
On our tests, used a few evenings a week over a mild month with the heater on a timer and a good insulating setup, the tubs cost between about £34 and £48 a month to run. The cheapest was the small-volume Wave Spa Atlantic at roughly £34, followed by the Bestway Lay-Z-Spa Bali at about £38 and the Intex PureSpa Bubble at about £40. The six-person tubs cost more: the heat-retaining Lay-Z-Spa Paris at about £42, the CleverSpa Maevea at about £46 and the large 930 L MSpa Comfort Bergen at about £48.
These figures are metered at the plug and assume an electricity unit rate broadly in line with the energy price cap set by the regulator Ofgem; your own rate will move the pounds up or down but not the ranking. They also assume good practice: the lid on between soaks, an insulating ground mat underneath and the heater on a schedule rather than holding 40°C around the clock. Skip those and the same tubs will cost noticeably more, because the heater simply fires more often. Winter use raises the figures too, sometimes substantially, since the heater has to fight much colder air.
What actually drives the cost
Three things determine your running cost, and only one of them is on the box. The first and biggest is water volume: a 600 L tub holds less water than a 930 L one, so there is less to heat in the first place and less to keep warm, which is why the small Wave Spa Atlantic was cheapest to run and the large MSpa Comfort Bergen dearest. The second is heat retention, which is how slowly the tub loses warmth; the Lay-Z-Spa Paris lost only 1.4°C an hour with the lid on, against closer to 2.5°C for a thinner-walled tub, so its heater spent far less time topping the water back up.
The third driver is your own insulation and habits, and this is the one you control most. Whether the lid is on, whether the tub stands on an insulating mat, whether it sits in the wind, and whether you hold 40°C all day or heat it just before use, all change the bill more than the choice between two similar tubs. Heater wattage, by contrast, is widely misunderstood: a 2,200 W heater warms the water faster than a 1,600 W one, but it does not directly make the tub cheaper or dearer to keep warm, which is governed by heat loss. In short, buy on volume and heat retention, then control the rest with good habits.
The cheapest inflatable hot tub to run
On our tests the cheapest tub to run outright was the Wave Spa Atlantic at about £34 a month, purely because its smaller 600 L volume means there is less water to heat and keep warm. If your priority is the lowest possible running cost and you mostly soak as a couple, a smaller tub is the rational choice, and the Atlantic is the one we recommend. Among the larger tubs, the most economical was the Lay-Z-Spa Paris, whose class-leading heat retention kept its running cost down to about £42 a month despite its 800 L six-person volume.
The pattern is clear: to spend the least, either buy a smaller-volume tub or buy one that holds heat well, and ideally do both. A small tub that also insulates well will always beat a large, poorly insulated one. If you are choosing between two tubs of similar size, the one with thicker walls and a better-fitting cover will cost less to run over a season, which is exactly why we measure heat retention rather than relying on the spec sheet.
How to cut your running costs
The single most effective step is to keep the insulating lid on whenever you are not in the tub. A hot tub loses most of its heat from the water surface, so an uncovered tub bleeds warmth and money continuously. Next, stand the tub on a thick insulating ground mat: a surprising amount of heat is lost into a cold patio or lawn, and a mat cuts that loss while protecting the base. Third, site the tub out of the wind, near a wall or fence, because moving air strips heat from the surface far faster than still cold air.
Beyond insulation, use the heater's timer rather than holding 40°C around the clock; heat the water to be ready just before you use it, and let it cool a little in between. Keep the filter cartridge clean so the pump and heater work efficiently, and consider a thermal blanket that floats on the water surface under the lid for an extra layer in cold weather. Together these steps cut our measured monthly bills by roughly a fifth. For winter specifically, our cold-weather guide adds the freeze-protection advice you need, and our buying guide explains how to choose a tub that is cheap to run in the first place.
Frequently asked questions
How much electricity does an inflatable hot tub use?
The heater is the big draw, typically 1,600 to 2,200 W, and it runs hardest during the initial heat-up and whenever it tops the water back up to temperature. Over a mild month of a few evening soaks a week, the tubs on test used roughly £34 to £48 of electricity. The single biggest lever you control is insulation: the lid, an insulating ground mat and a sheltered spot all cut how often the heater fires.
What is the cheapest inflatable hot tub to run?
On our tests it was the Wave Spa Atlantic at about £34 a month, because its smaller 600 L volume means less water to heat and keep warm. Among the larger tubs, the Lay-Z-Spa Paris was the most economical for its size thanks to the best heat retention we measured. In short, a smaller tub or a better-insulated one costs less to run.
How can I reduce my hot tub running costs?
Keep the insulating lid on whenever you are not in the tub, stand the tub on an insulating ground mat, and place it out of the wind. Use the heater's timer so it warms the water just before you use it rather than holding 40°C all day, and keep the filter clean so the pump works efficiently. Together these steps made a clear difference to our monthly figures.
Our advice
An inflatable hot tub need not be expensive to run if you choose and use it well. Expect somewhere between about £34 and £48 a month with good practice, more in winter, and remember that water volume and heat retention set the baseline while your own insulation and habits do the rest. Buy no bigger than you need, favour a tub that holds heat well such as the Lay-Z-Spa Paris or the small, cheap-to-run Wave Spa Atlantic, then keep the lid on, use an insulating mat and run the heater on a timer. Do that and the running cost becomes a manageable part of a pleasure rather than a nasty surprise. See our how we test page for exactly how we meter these figures.