Advanced options
What The Hot Tub Running Cost Calculator Works Out
- Per day: kilowatt-hours per day x the electricity price. A hot tub's bill is mostly the physics of holding several hundred litres at 38 degrees outdoors: a modern well-insulated tub averages 5 to 8 kWh a day across the year, older, cheaper or inflatable tubs 10 to 14, because thin walls insulate poorly.
- Per month and per year: the daily cost x 30.44 and x 365. The price defaults to the current Ofgem price cap unit rate (26.32p per kWh from October 2026), at which the realistic annual range is about GBP 480 to GBP 1,350 in electricity, with winter months costing two to three times summer ones. The heater dominates; circulation pumps run constantly at low power and jets and lights are trivial.
- Your own kWh per day (advanced): override the list with a figure from a plug-in energy monitor or smart meter, which is the only way to know what your tub really draws.
- Months in use (advanced): scales the annual figures for a tub drained or switched off for part of the year. Note that an empty tub still needs frost protection if left outside.
- All-in cost per year (advanced): electricity plus sanitiser, pH balancers and shock treatments (typically GBP 15 to 25 a month) plus filters and a full water change every 3 to 4 months. The non-electric costs are steady rather than large.
- Cost per soak (advanced): the all-in annual cost divided by your soaks per week over the year. Because most of the cost is keeping the water hot regardless of use, soaking more often makes each soak cheaper.
- Off-peak heating saving (advanced): the share of heating moved to a cheaper overnight rate and the resulting blended price. Time-of-use tariffs suit tubs well, since the heater can be timed to run on cheap hours and the insulation carries the heat through the day.
- Cover or set point saving (advanced): a percentage cut in electricity from a tight-fitting insulated lid with a thermal blanket beneath (most heat leaves through the water surface) or dropping the set point a couple of degrees. Waterlogged covers stop insulating; 10% to 20% is a typical gain.
- Electricity used per year (advanced): annual kilowatt-hours for context. A hot tub can match or exceed the 2,700 kWh a typical home uses for everything else, which is why insulation quality is worth paying for up front: over a decade the efficiency gap between a budget and a well-built tub exceeds the price gap.