What Temperature Should a Hot Tub Be?

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After a long day at work or watching the kids, it's nice to be able to sit down and relax. It's even nicer when the relaxation can be done in the comfort of a hot tub that you or your friend(s) own(s).

However, no matter how much you may ache (literally) for your hot tub time, safety should be at the forefront of your mind. Part of hot tub safety is knowing and maintaining the proper hot tub temperature. Below is a short but simple guide to what temperature is safe for hot tubs and what factors you should consider when setting the thermostat.


The official recommendation for hot tub temperature is 40 degrees C. Settings higher than 40 degrees C are believed to raise health risks because such high temperatures raise individual body temperature to levels higher than the body can tolerate safely. The 104 degree recommendation has led to most hot tub manufacturers putting controls on their hot tubs that do not allow the temperature to rise much, if at all, above 40 degrees C. Some manufacturers recommend not placing the temperature above 38.9 degrees C and claim that this temperature usually is satisfactory to most hot tub users.

Highest Temperature

Hot tub temperatures can feel higher or lower than the thermostat setting based on the individual's preference. This has resulted in some individuals bypassing the 104 degree recommendation and turning the thermostat higher. Occasionally thermostats also malfunction and read incorrectly. Regardless of what the water temperature feels like, and no matter what the tub thermostat reads, hot tubs should never reach over 43.3 degrees C. At this temperature, the physical safety threshold is easily crossed.


Age impacts what setting the hot tub thermostat should have. Adults generally can tolerate higher temperatures than young children can. This is because young children have a harder time adapting to temperature shifts than adults do.

Physical Condition

Physical conditions can impact how hot your hot tub should be. Extremely hot temperatures in tubs need to be avoided by pregnant women not because it is especially harmful to the woman, but because it can be harmful to the foetus. Similarly, those with heart conditions and hypertension should turn down their hot tub thermostats a bit from the recommended 40 degrees C because heat will raise blood pressure. This could lead to a stroke, heart attack or even death. Obesity is also another consideration, since obesity often is associated with higher blood pressure and because it can be harder for an overweight person's body to stay cool.

Diet and Medications

Many medications, foods and drinks impact an individual's internal body temperature and blood pressure. If an individual is on a medication or has eaten something that affects blood pressure, or if the individual has been drinking alcohol, the temperature of the hot tub should be set at a temperature lower than the recommended 40 degrees C.

Personal Tolerance

Not everyone's internal body temperature is 37 degrees C. It is normal to run a degree or two higher or lower than this average. This means that, regardless of how much someone may weigh, he may be more or less affected by a particular temperature than someone else. Some people may feel like 37.8 degrees C is too hot, while some may not feel warm until the temperature in the tub is at the 104 degree recommendation. Hot tub temperature thus can be adjusted (within reason) according to the user's preference.

Number of People

The more people in a hot tub, the cooler the water will feel. For this reason, an individual can turn up the thermostat a little if the number of people in the tub increases. She can turn down the thermostat if the number of people in the tub decreases.