A hot tub is the one garden appliance that can go toe to toe with your heating bill. It is not the odd evening soak that costs the money — it is keeping around 1,000 litres of water at 38°C every hour of every day. At the Ofgem cap for 1 July – 30 September 2026 (26.11p per kWh), that runs from roughly £286 a year for a well-insulated tub to over £850 for a thin inflatable left out through winter.
The numbers, by how much heat your tub loses
Running cost tracks daily energy use almost perfectly, and daily energy use tracks heat loss. Here is the year at the current price cap, by average daily consumption:
| Tub & conditions | Per day | Per day cost | Per year |
|---|---|---|---|
| Well-insulated rigid tub, summer | 3 kWh | 78p | £286 |
| Well-insulated rigid tub, year-round | 4 kWh | £1.04 | £381 |
| Typical tub, average cover | 5 kWh | £1.31 | £476 |
| Inflatable, decent cover | 7 kWh | £1.83 | £667 |
| Inflatable, thin cover, winter | 9 kWh | £2.35 | £858 |
Note what is not in that table: how often you use it. Two soaks a week or ten, the tub spends the other 160-plus hours simply holding temperature, and that is where nearly all the electricity goes. Usage barely moves the annual figure. Heat loss is the whole game.
Why winter costs double
The colder it is outside, the harder the heater works to hold 38°C, so the same tub costs far more in January than in July. A tub averaging 4 kWh a day across the year might sit at 2–3 kWh in summer and 6–7 kWh in the depths of winter. If your use is seasonal, the single biggest saving is simply draining and switching off for the coldest months rather than paying to keep an unused tub hot through them.
What actually cuts the bill
- A tight, thick cover — the biggest lever by a distance. A worn or waterlogged cover can add hundreds a year.
- A thermal floor blanket — cuts loss through the base, which most tubs leak heat through.
- Lowering the set temperature — even 1–2°C reduces the standing heat loss noticeably.
- Sheltering the tub — out of the wind loses far less heat than exposed in an open garden.
- A floating thermal blanket under the cover — an extra insulating layer on the water surface.
Chasing a more efficient pump or a fancier heater misses the point: on a hot tub, insulation is the efficiency. Fix the cover before you spend on anything else.
Is it worth it?
That is a lifestyle call, not a maths one — but go in with eyes open. A hot tub is a several-hundred-pound annual commitment, closer to running a second fridge-freezer many times over than to the odd luxury. If that number is comfortable, a well-insulated tub with a good cover keeps it as low as it can go. If it makes you wince, the culprit is almost always the cover and the winter months, and both are fixable. For context, this is still small next to what heating the whole house costs — see our honest look at heat pumps for the number that really dominates a UK energy bill.