Sauna Temperature: How Hot Is a Sauna and What Should It Be?

A traditional sauna is usually 70°C to 100°C (158°F to 212°F) with low humidity, and most gym and spa saunas in the UK sit around 75°C to 90°C. Infrared saunas run far cooler at 45°C to 65°C, steam rooms at about 40°C to 45°C but near 100 percent humidity, and home steam tents and sauna blankets have their own, lower ceilings. If you're asking what temperature a sauna should be, the honest answer is 70°C to 80°C for a beginner in a Finnish sauna and whatever you can sit in comfortably for 10 to 15 minutes once you're used to it.

The number on the dial is only half the story, though. Humidity changes how hot that number feels, and where the thermometer sits changes what it tells you.

Sauna temperatures by type

Type	Typical air temperature	Humidity	Typical session
Traditional Finnish (dry) sauna	70°C to 100°C	Around 10 to 20%, spiking with water on the stones	8 to 15 minutes per round, 2 or 3 rounds
Infrared cabin or tent	45°C to 65°C	Low and constant	20 to 40 minutes, one sitting
Steam room	40°C to 45°C	Close to 100%	10 to 15 minutes
Portable steam tent	Quoted maximums of around 45°C to 54°C	Near saturation	15 to 30 minutes
Infrared sauna blanket	Controllers usually run 25°C to 80°C	Low	30 to 45 minutes

The blanket figure needs a caveat. That's the temperature of a heated liner wrapped around you, not the air in a room, so it isn't comparable with a sauna reading. Most owners of the blankets we've covered settle between 60°C and 70°C, because the top setting against bare skin is uncomfortable rather than useful.

For the deeper comparisons between formats, our guides to infrared vs traditional saunas and sauna vs steam room cover how each one heats you and what the research does and doesn't support.

Why 80°C dry and 80°C with steam feel completely different

Your body's main way of dumping heat in a sauna is sweat evaporating off your skin. In dry air at 10 to 20 percent humidity that works well, which is why people can sit in 90°C air for ten minutes without their core temperature running away.

Throw a ladle of water on the stones and you get löyly, the burst of steam Finns consider the best part of the whole experience. The thermometer reading hardly changes, but the humidity jumps for a minute or two and your sweat suddenly struggles to evaporate. The heat then lands on your skin (and your ears, which always seem to feel it first) and the room feels several degrees hotter. Take that to the extreme and you have a steam room, where 45°C saturated air can feel more oppressive than 85°C in a dry sauna.

Two practical consequences follow from that. A hot sauna plus lots of water on the stones is a much bigger heat load than the dial suggests, so go easy on the ladle until you know your limits. And in shared saunas, ask before adding steam, since it changes the room for everyone; our sauna etiquette guide covers the unwritten rules.

What temperature should a sauna be?

It depends on who's in it and what they're after, but these ranges work for most healthy adults:

• First few sessions: 70°C to 80°C, lower bench, 5 to 10 minutes per round. Get out, cool off with a shower, rest for at least five minutes and only go back in if you feel fine.
• Regular users: 80°C to 90°C, 10 to 15 minutes per round, two or three rounds with cool-downs in between. This is roughly the range the large Finnish studies were built on.
• Experienced users: 90°C to 100°C in shorter rounds. Hotter isn't automatically better, and nobody has shown that 100°C beats 85°C for health.
• Infrared: start at 45°C to 55°C for 15 to 20 minutes, then work up to 55°C to 65°C for 30 minutes or so.

Bench height matters more than most people realise. Heat rises, so the top bench in a stove-heated room is noticeably hotter than the bottom one, and moving down a level is the easiest way to turn a 90°C sauna into something a beginner can handle.

The research reason people chase the hotter end comes from Finland. A 2018 review led by Jari Laukkanen summarised observational and trial evidence linking regular Finnish sauna bathing with lower risk of high blood pressure, cardiovascular disease and death from all causes (Laukkanen et al., Mayo Clinic Proceedings). Those findings come mostly from cohort studies of Finnish men using hot, dry saunas several times a week. They show an association, not proof that the heat itself caused the benefit, and they say nothing direct about a 50°C steam tent.

How to measure sauna temperature properly

Sauna thermometers are usually mounted high on the wall above the top bench, roughly where a seated person's head would be, and that's the right place for one. A thermometer near the floor or by the door will read far lower than the air you're actually breathing, which is how people end up believing their sauna is gentler than it is.

A few tips for getting an honest reading:

• Keep it away from the stove. A thermometer right next to the heater reads hot and makes the room seem hotter than it is everywhere else.
• Wait for the room to settle. An electric Finnish sauna typically needs 30 to 45 minutes of preheating before the air and the timber reach a stable temperature.
• Use a hygrometer too. A combined thermometer and hygrometer tells you humidity, which explains why the same reading feels different from one day to the next.
• Don't trust the controller on cheap tents. Many portable units show the setting rather than a measured air temperature, so a separate thermometer at head height inside the tent is the only way to know.

What home saunas actually reach

This is where expectations and reality part ways. A proper electric Finnish sauna with a 4.5kW to 9kW heater will hit 80°C to 100°C, but it usually needs a dedicated circuit and costs several thousand pounds once installed.

The plug-in options are cooler. Infrared cabins such as the Home Deluxe Redsun in our best home sauna guide sit at a gentler 50°C to 60°C. Portable infrared tents mostly peak around 60°C; the CONLONS we reviewed is one of the warmer ones at about that figure, with your head inside the heat. Single-person steam tents are cooler again, with SereneLife quoting 50°C and Manastin about 54°C, and your head usually stays outside in room air.

Check price on Amazon

None of that makes a home unit pointless. Twenty or thirty minutes of steady heat still gets you sweating hard and is a decent way to wind down after training. Just buy one for what it reaches, not for the 80°C-plus research it was never tested against.

Staying safe at any temperature

A systematic review of regular dry sauna use found 40 studies with broadly positive results and only one reported adverse outcome, a reversible drop in sperm production in a small group of men (Hussain and Cohen, 2018). That's reassuring for healthy people, but the authors also pointed out that data on side effects is thin, so the common-sense rules still apply.

• Drink before and after. You can easily lose half a kilo to a kilo of sweat in a 20 minute session, more on top of a workout. Our guide to using a sauna after a workout covers timing and fluids.
• No alcohol. It dulls your sense of overheating, adds to dehydration and makes the drop in blood pressure as you stand up more likely to end in a faint.
• Stand up slowly. Heat widens your blood vessels and lowers blood pressure, so light-headedness on the way out is common. Sit for a moment before you leave the bench.
• Know the warning signs. Dizziness, headache, nausea and intense thirst are the early signs of heat exhaustion, and the NHS advice is to cool down and take fluids straight away (NHS: heat exhaustion and heatstroke). Get out at the first one, whatever the clock says.
• Check with your GP or midwife first if you're pregnant, have a heart condition, take blood pressure medication, or have recently had a heart attack or chest pain.

Recommended reads

1. Infrared sauna vs traditional sauna
2. Sauna vs steam room: which is better?
3. Sauna etiquette: the rules nobody tells you
4. The best home sauna in the UK
5. All our recovery guides and reviews