How we test inflatable hot tubs

Every ranking on SoakVerdict comes from the same hands-on process: real tubs, set up in a real garden, with the same measurements taken on each one. Here is exactly how we reach our verdicts, step by step.

We fill and live with every tub ourselves

We do not score inflatable hot tubs from a spec sheet. Each tub that makes our shortlist is set up in the garden the way you would set up your own: inflated with the supplied pump, stood on an insulating ground mat on a level patio, filled from a garden hose and heated from cold. We then use it the way a real owner does, over a mix of evening soaks across several weeks, in the actual British weather, because a tub that looks good on paper but heats slowly, loses warmth quickly or feels flimsy underfoot has nowhere to hide once you have lived with it for a fortnight. Crucially, we test each tub in the same spot, with the same insulation, so the comparison between models is fair.

The measurements we take

To keep our comparisons fair and repeatable, we take the same set of measurements on every tub.

• Heat-up time, from a cold fill. We fill each tub from the mains, note the starting water temperature (typically around 15°C from a British outdoor tap), switch the heater on with the lid on, and time how long it takes to reach the maximum 40°C. This is the single most practical figure for an owner, because it tells you how far ahead you need to switch the tub on. In our latest test the figures ranged from about 16 hours on the smaller-volume Wave Spa Atlantic to about 24 hours on the larger budget tubs.
• Heat retention, lid on, heater off. This is the figure manufacturers never publish, so we measure it. With the tub steady at 40°C, we switch the heater off, put the insulated lid on, and log the water temperature every fifteen minutes with a probe thermometer to see how fast it falls. We report the loss as degrees per hour. The best tub on test lost only 1.4°C an hour; a thinner-walled tub shed closer to 2.5°C in the same conditions. Heat retention drives both comfort and running cost, so we weight it heavily.
• Running cost, metered over a month. We run each tub through a plug-in energy meter for a month of typical use, a few evening soaks a week, with the heater on a timer, the lid on between soaks and an insulating mat underneath, and record the electricity used. We convert that to a monthly figure using a unit rate broadly in line with the Ofgem energy price cap, so the numbers are comparable. Our tubs ranged from about £34 to £48 a month.
• Inflation and drain time. We time how long each tub takes to inflate from flat with its supplied pump and how long it takes to drain, because both affect how easy the tub is to live with and to pack away. Inflation ran from about 10 to 15 minutes across our tubs.
• Pump noise, at one metre. We measure the pump-heater noise with a sound-level meter at one metre while heating, because a tub that drones across the garden is less pleasant to sit beside. Our tubs measured between about 62 and 67 dB.

The things we judge by hand

Numbers tell most of the story, but not all of it, so we also assess the things you can only judge by using a tub. We check the build and rigidity: how firm the walls feel when you lean on them, whether a rigid frame keeps the structure steady, and how secure it feels to climb in and out. We assess seat comfort and depth, because a tub with shallow seats leaves taller users cold even at 40°C. We test the bubble system for how even and pleasant the fizz is across the whole floor, rather than just counting jets. And we judge the cover, app and controls, since a thick insulating lid saves real money and a clear app makes planning heat-up far easier.

How we score and rank

We bring the measurements and the hands-on judgements together into a verdict for each tub, and then into an overall ranking. Heat retention and running cost carry the most weight, because they decide whether you actually use and can afford the tub over a season, followed by capacity and comfort, build quality, features and price. Crucially, we do not rank tubs against a single ideal; we rank them for the buyers they suit. That is why our list has a best overall, a best value, a best budget, a best for small gardens, a best for couples and a premium pick, rather than just one winner. Every review says clearly who a tub is, and is not, for.

Why our rankings are never for sale

SoakVerdict is funded by affiliate commissions, which means we may earn a small amount when you click a link to a retailer and buy a tub, at no extra cost to you. That funding pays for the testing and keeps the site free, but it has no influence on our rankings. We are not paid by manufacturers to feature or favour their tubs, we do not accept money for higher positions, and our order is decided entirely by how the tubs perform against the criteria above. If the cheapest tub is the right one for you, that is what we will say. You can read the full detail in our affiliate disclosure, and learn more about who tests these tubs on our about page.

Keeping our reviews current

Inflatable hot tubs change less often than gadgets, but ranges are updated, prices move and new models arrive, so we revisit our tests and refresh our recommendations as the market shifts. Each review carries the dates it was tested and last updated so you can see how current it is. Prices, in particular, change frequently, so we treat the figures on this site as indicative and always point you to the retailer's own page for the definitive, up-to-date price at the moment you buy. If you spot something out of date, or have a tub you would like us to test next, our buying guide and contact details are the place to start.