It’s easy to choose the right temperature when you are using a hot tub, but how to determine the optimal hot tub temperature when not in use is more uncertain. As a rule of thumb, when not in use, the hot tub temp should be set at least 5 degrees Fahrenheit lower than when active.

This post may have affiliate links, which means I may receive commissions if you choose to purchase through links / provide (at no extra cost to you). As an Amazon Associate, I earn from qualifying purchases. Please read my disclaimer for additional details.

Basic knowledge of ideal hot tub temperature

A hot tub sounds perfect after a tiring day on the condition that its temperature is just right, not too hot or too cold. A majority of hot tub users enjoy temperatures from 97 to 100.5 degrees Fahrenheit (36.1 – 38 degrees Celsius).

However, to be considered ideal, a temperature depends on various factors such as users’ body temperature, weather, and other health and safety risks.

Most hot tubs can have the lowest temperature at 78.8 degrees Fahrenheit (26 degrees Celsius), but this temperature level is only suitable in summer and when you want to cool off.

On the contrary, under colder weather such as winter, the British and Irish Spa and Hot Tub Association (BISHTA) suggested that the maximum safe temperature that you can set for your hot tub is 104 degrees Fahrenheit (40 degrees Celsius) because any temperature higher than this level can pose serious health risks and danger to its owner.

There is no one answer for the ideal hot tub temperature since it depends heavily on personal preference. Some like it lukewarm, while others can prefer it a little bit hotter.

However, a good starting point is human body temperature. Therefore, most hot tub factory settings are set at 100.4 degrees Fahrenheit (38 degrees Celsius) which seems to give the most comfort to the users when they enter the hot tub and to leave room for the temperature to reduce.

Determining the hot tub temperature matters because it can cause health risks for users, especially the vulnerable like pregnant women and kids.

  • Safe temperature for a pregnant

Pregnant women should be cautious when using a hot tub because there are risks of overheating, dehydration and fainting. If their body temperature is over 100.4 degrees Fahrenheit (38 degrees Celsius), they and their baby will face these risks, especially during the first 3 months.

Pregnant women should always ask for consultation from their doctor or midwife regarding how to use their hot tub safely. It may be advised that they set the temperature below 95 degrees Fahrenheit (35 degrees Celsius) and stay in the tub for under 10 minutes.

During their time in the hot tub, pregnant women should avoid putting their head, arms, shoulders, and upper chest underwater. If they feel uncomfortable at any point, they should get out of the hot tub immediately.

  • Safe temperature for kids

hot tub for kid

It is recommended that kids younger than 5 years old should not use hot tubs.

In case your child is older than 5 since children have a lower ability to regulate their body temperature than adults, the recommended hot tub temperature is 95 degrees Fahrenheit (35 degrees Celsius).

Setting hot tub temperature when not in use

The ideal hot tub temperature when not in use should be at least 5 degrees lower than your desired in-use temperature. Maintaining the hot tub temperature at a lower temperature helps prevent the energy consumption from going up too high.

However, this practice should only be done if you use your hot tub sporadically (under 2 hours per week). If you use it regularly, you will not save any energy consumption because the water in the hot tub reduces its heat slowly, which takes more energy to reheat.

For a number of hot tub models, setting a lower temperature makes the controller automatically switch to “summer mode”. Then, the tub will shut off the circulator pump or filter cycles to avoid generating any additional heat.

If the hot tub is not in use for a while, setting a lower temperature according to the rule of thumb will save you a bit of money. It’s best to set the hot tub temperature at a level that you can reheat the hot tub to a normal temperature in the lead time that you expect.

For instance, if your hot tub heats 4 degrees per hour and you are willing to wait for 30 minutes, you should maintain the hot tub temperature when not in use at 2 degrees lower than when in normal use.

In addition, most hot tubs have an economy mode in which the heater works less during the day. This can save you a little money too and it’s also a great way to maintain lower temperatures of the hot tub during summer.

For every degree Fahrenheit, you decrease your hot tub temperature, you will save approximately 10% on its corresponding electricity costs. Nevertheless, the owners usually spend about $20-$50 monthly on their hot tub, so it’s not a huge saving.

Should you turn off the hot tub when not in use?

turn off hot tub

Many people turn off their hot tub when not in use because they think that it will save energy. But personally, I think that you should not switch the hot tub off completely, because when you try to heat the water up again, it will consume even more energy.

You should only consider turning it off completely when you are about to be away for at least 3 weeks.

If the weather is too cold, you should leave the hot tub running or winterizing to avoid a cracked pipe and a cracked shell.

What if the hot tub is not in use for months?

If you are going to be away on vacation for months and no one helps to take care of the hot tub, there are a number of things you should follow before leaving. These precautions will depend on the weather.

  • Hot weather

Common issue: Algae growth

What to do:

– Add extra shock to the tub, operate the jets for 30 minutes

– After the shock has fully reached the water, shut off the hot tub

  • Cold weather

Common issue: Frozen pipes, frozen water

What to do:

– Heat the water before leaving

– Set the thermostat to 10 degrees lower to prevent frozen pipes

– Or, drain the hot tub and then winterize it

In a nutshell

“What temperature to set hot tub when not in use?” is probably a question off the top of any hot tub owner’s head.

You should maintain the temperature of your hot tub at least 5 degrees Fahrenheit lower than the level when in use. However, if you don’t use the hot tub for over 3 weeks, you should turn it off completely.


Leave a Comment