What to wear in a sauna
Venue rules, fabric behaviour and the short answer: less, and made of something natural.
The short answer: a towel, and as little else as the venue allows. The longer answer is about what fabric does in a hot, wet room — because most modern clothing is designed for moving in cool air, which is close to the opposite situation.
What the venue expects
UK spas, gyms and lidos almost always expect swimwear, and mixed-sex facilities usually require it. A cotton or linen towel to sit on is standard courtesy everywhere, and in many places mandatory — you sit on the towel rather than the bench.
Finland, Germany, Austria and much of the Nordic and Central European world run textile-free saunas, often mixed, with a towel used for sitting rather than covering. It is a hygiene norm rather than a statement. If you are travelling, check the venue's page; the rules are always published and rarely negotiable.
Why fabric matters more than you would think
A hot room is a difficult environment for clothing. Plastic-based fibres absorb very little moisture, so sweat sits between fabric and skin instead of being taken up, and in still, humid air there is no evaporation to move it along. The result is a clammy layer that feels worse the longer you sit.
Elastane is the specific problem. Repeated high heat degrades it, which is how swimwear loses its shape and prints go patchy after a season of sauna use. Chlorine and heat together accelerate that further. This is material behaviour rather than a safety issue, but it is a good reason not to bring your best kit into a 90°C room.
Cotton and linen absorb moisture into the fibre and dry as they cool. Wool does the same and manages odour better. In a sauna, natural fibres simply behave.
What to wear
- A cotton or linen towel. To sit on, always. Large enough that no skin touches the bench.
- Simple swimwear if required. Plain, well-fitting, and ideally not the pair you care about. Expect heat to shorten its life.
- A wool felt sauna hat. The one addition that genuinely improves the session, because the head heats first.
- Nothing else. Leave jewellery outside — metal gets hot. Same for watches, which also dislike the heat.
What to leave outside
- Gym kit. Polyester and elastane in a hot room is the worst-behaving combination available.
- Anything heavily printed or coated. Prints and finishes crack and lift with repeated heat.
- A wet towel on your head. It cools for two or three minutes, then becomes a warm compress. Dry felt insulates for the whole session.
- Shoes. Flip-flops to the door, then off. Nothing with rubber soles onto the benches.
Between rounds
Take everything off in the cooling phase — hat included — so it can dry rather than sit warm and damp. A dry robe or a large towel for the rest phase is genuinely worth having, because the rest is where the session lands and being cold cuts it short.
Common questions
- What should I wear in a sauna in the UK?
- Swimwear in most UK spas, gyms and lidos, plus a cotton or linen towel to sit on. Some private and Finnish-style venues are textile-free — the venue will state its rule.
- Can you wear gym clothes in a sauna?
- Better not to. Polyester and elastane absorb almost no moisture, so sweat sits against the skin, and repeated high heat degrades elastane and printed finishes.
- Do you have to be naked in a sauna?
- Only where the venue is textile-free, which is common in Finland, Germany and Austria and rare in UK public facilities. A towel to sit on is expected either way.
- Should I wear a sauna hat?
- If the room is hot and dry, yes. The air at head height is the hottest in the room, and wool felt keeps the head comfortable long enough to complete a full session.
Continue reading
- What to take to a sauna — the whole bag, and what you can leave behind.
- The sauna hat: a UK buying guide — how to choose the one thing worth adding.
- What are we wearing when we sweat? — why plastic-based fabric behaves the way it does.
One object, made properly, for the hottest part of the room.