What temperature should a hot tub be?

 Woman holding a smart phone with hot tub temperature on

There is nothing worse than getting into a hot tub that is either too warm or too cold. The majority of users enjoy a hot tub temperature range between 36°C and 38°C, however, the ideal temperature will depend on a variety of factors, including body temperature, weather conditions and a number of health and safety risks.

Most hot tubs can be set as low as 26°C, but this would only be appropriate if it is a hot summers day and you want to use your tub to cool off.

The maximum safe recommended hot tub temperature is 40°C, as anything higher than this can be dangerous, posing serious health risks to users.

Finding the ideal hot tub temperature

The ideal hot tub temperature comes down to one thing, personal preference. However, 40°C is the highest safe hot tub temperature and is the industry agreed maximum, with BISTHA stating that bathing in water exceeding 40°C is potentially harmful and should be avoided.

Your body temperature is a good place to start when it comes to the temperature of the hot tub water. Most hot tubs factory settings will be set at 38°C, which is 1 degree higher than the average normal body temperature. This temperature seems to be the most comfortable for bathers to enter. It also allows room for the temperature to drop, something that naturally occurs when people enter the water.

Why hot tub temperature matters

Safe hot tub water temperature is important for everyone but more so for the vulnerable because of the potential health risks involved.

Anyone who has underlying health conditions should always consult a doctor or other medical professional before using a hot tub.

Safe Temperature for hot tub while pregnant

During pregnancy, you should use your hot tub with caution. Even just 10 minutes sat in the hot water can raise body temperature higher than 38°C, which is something that should be avoided when pregnant because of health risks to you and your developing baby. It's advisable to avoid using your hot tub when pregnant because of the risks of overheating, dehydration and fainting. It's possible that a significant rise in your core temperature could be harmful in pregnancy, particularly in the first 12 weeks.

If you plan to use a hot tub when pregnant, always consult your doctor or midwife about the safest way of doing so. You may be advised to lower the temperature below 35°C and limit soaking time to less than 10 minutes. Avoid submerging your head, arms, shoulders and upper chest and if you feel any discomfort, get out of the tub straight away.

Safe hot tub temperature for kids

The CDC (Centers for Disease Control and Prevention) recommends that children under the age of 5 should not use hot tubs. However, if your child is over the age of 5, a slightly lower temperature of 35°C is advised because children are less able to regulate their body temperature.

Children should always be supervised when using a hot tub to avoid any accidents and always ensure they drink plenty of water to avoid dehydrating.

Heat related health risks

Hot tubs are great for relaxing and can ease aches and pains from conditions like arthritis, back pain and fibromyalgia. Using your hot tub when unwell or if your body temperature exceeds 39°C it can cause potential problems such as:

  • Dehydration
  • Heat exhaustion
  • Heat stroke
  • Heat rash
  • Heat cramps

Prolonged exposure to heat could also aggravate any pre-existing chronic conditions such as respiratory, cerebral and cardiovascular disease.

We always recommend consulting a medical professional before use if you have any underlying conditions.

How long does a hot tub take to heat up?

There are various factors that can affect how long it takes to heat a hot tub up. These factors include: the temperature of the water that is started with, how efficient your hot tub is and the quality of installation.

Most hot tubs will rise between 3 to 6 degrees per hour, taking anywhere between 4 to 20 hours to reach the correct temperature. If you want to speed up the process, make sure to leave the cover on so the heat can’t escape. The temperature of the air outside can also be a factor, so the warmer it is the quicker your hot tub will heat up.

The good thing about hot tubs is that they maintain their heat, meaning you will only have to wait for your tub to heat up if you’re setting it up for the first time or you have drained the water.

How to change hot tub temperature

Most hot tubs will have an electronic control panel that is used to maintain or adjust the water’s temperature. This will display the current reading of the water, in which you can decide whether you want to increase or decrease the temperature. The buttons on your control panel should be clearly labelled, usually with a plus and minus symbol. Use the plus to increase the temperature by one degree or the minus if you want to decrease it.

Hot tub temperature when not in use

If you’re not going to be using your hot tub for an extended period, avoid turning it off completely and keep it at a lower temperature of around 30°C. Turning off your hot tub isn’t necessary as this can use more energy when reheating it and will be less cost efficient. You will still need to check the chemical balance during this time.

Hot tub weather dependencies

Being able to change your hot tub temperature allows you to relax and unwind all year round, whether it’s winter or summer. Lowering the temperature in summer will give you a cool, refreshing boost on a hot day and in winter, you can sink into the warm water as you watch the steam rise into the cold air.

Hot tub temperature in winter

The winter months is when most people will take full advantage of their hot tub. We always recommend keeping the temperature at 38°C, not only will this keep you warm, it also helps to protect your hot tub as the heat generated stops your power pack from freezing over. Make sure to always keep the cover on when you’re not using it, so the heat doesn’t escape.  

Hot tub temperature in summer

Hot tubs don’t just have to be used in the winter; you can also use them to cool off in the summer too. Depending on how cool you want the water to be, we recommend experimenting with temperatures between 29 and 35°C to find the most comfortable temperature to suit you.

If you’re in a rush to cool down your hot tub, turn on the water jets after you’ve dropped the temperature as the circulation of the water will cool it down quicker.

Find out more about making the most of your hot tub in summer with our top tips.

The ideal hot tub temperature is generally down to someone’s own personal preference, it’s all about how to balance comfort with safety. Enjoying the heat from your tub really does make you feel relaxed and helps you to unwind.

If you want more tips on how to destress using your tub, read our blog post and discover our top 10 stress busting tips.