Hot tubs take on average between three to six hours to heat up. This of course depends on your hot tub size, the power of your heater, the quality of your cover and your starting water temperature. The first few hours are the slowest, but don’t be deterred or disheartened, as once it gets moving it heats up much faster and you will be in your tub in no time. Plus, there are some things that you can do to speed that up a little. 

The rule of thumb is that for every hour you heat your hot tub, the temperature will rise anywhere between 2 and 6 degrees, and this can be aided through a hot tub cover, good insulation and a solid hot tub maintenance plan.

TOP TIP: Make sure your hot tub is NOT in economy mode on specific models.

How hot should my hot tub be?

You want to be looking at between 36°C and 38°C on average, but this will vary during different times of the year and personal preference.

hot tub inground decking

Timing is everything

It might be useful to plan when you’re wanting to use your hot tub, and back timing your heating time from there. This way, you will know for sure that your hot tub will be bubbling and ready for action.

There are a number of factors to consider when looking at how quickly your hot tub will heat up, all of which have a direct correlation to temperature and time.

Heater capacity

Firstly, the most obvious thing to look at is the power of your heater. The more KW, the quicker your hot tub is going to heat up – but it does mean that it will use more energy and electricity. This is very much short term pain and long term gain, as once your hot tub is heated up, you will be able to maintain the temperature which is far less energy and cost intensive than heating it from scratch each time that you want to use it.

TOP TIP: Hot tubs are designed to be left on all the time. Do not turn it off to avoid high wait times.

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Outside temperature

The outside or surrounding temperature, known as the ambient temperature, is also going to have a significant effect on how quickly your hot tub heats up. If you live in warmer weather, the water will heat more easily, but likewise if you’re heating your tub during a UK Winter, then that cold air is going to have a significant impact on the heating of your hot tub water. 

Shell insulation

Hot tubs come with varying degrees of insulation, and some of the more entry level models have poor or little insulation. This means that the heat escapes more easily, and they can take longer to heat. You can purchase additional insulation if this is a concern for heat loss, which can really speed up the hot tub heating process. 

High quality cover

The cover that you choose for your hot tub will also be a key purchase decision for heating your hot tub. The better quality the cover and the insulation provided as part of that, the quicker you will be able to enjoy your tub at optimum temperature. Hot tubs lose around 60% of their heat through surface water, so covering this up is a sure fire way to heat your tub more quickly and efficiently.

hot tub cover

Size matters

The size of your hot tub will be a great contributing factor to how long it will take to heat, also. Practically, an eight person hot tub is going to take twice as long to heat as a tub that caters for four people.

How long will your hot tub stay warm?

Providing it is left on, your hot tub will stay warm. Of course, if it is left uncovered or if you turn down the temperature, this will have an effect on the water temperature. However, if you adhere to the guidance and leave your hot tub on, it will be ready for action when you are. You only need to heat up your hot tub from scratch the first time you fill it up, and then when you refill it as part of your maintenance routine.