What to Wear in a Sauna

The traditional answer is a towel and nothing else — but the right answer depends on where you are and how hot the room gets. A public gym, a mixed spa, a private home cabin and a traditional Finnish sauna each carry different norms, and a few materials genuinely misbehave in high heat. This guide walks through the sensible default, when swimwear makes sense and what to watch out for, the cotton-versus-synthetic question, the things you should take off before you go in, and the one counter-intuitive accessory — a wool hat — that actually makes a hot traditional sauna more comfortable. None of it is complicated once you know the reasons behind it.

The default: a towel

In traditional sauna culture, the answer is simple — you wear a towel, or nothing, and you sit on a second towel. The Finnish Sauna Society treats bathing without clothing as the norm, usually in gender-separated rooms, and clothing is sometimes actively discouraged as less hygienic than bare skin on a clean towel. Even where nudity isn't expected, a towel is the most heat-friendly choice there is: nothing to trap sweat against your skin, nothing to overheat, nothing with a seam or fastener to press on you. If you're ever unsure what to wear, a towel is never wrong. In a private home sauna, this is the easiest default of all — it's your cabin, and a towel is comfortable, hygienic and fuss-free.

When swimwear makes sense — and its caveats

Swimwear is the practical, modest default in most public, mixed-gendersettings — a gym, a hotel pool deck, a co-ed spa sauna — and if you're moving between a sauna and a pool or cold plunge, it's the obvious choice. It's completely fine. But high heat does expose a few caveats worth knowing:

• Metal fasteners get hot. Clasps, hooks, underwire and zippers can heat up enough to be uncomfortable against skin. Prefer swimwear without metal hardware for the sauna.
• Tight synthetics trap heat and sweat.A snug polyester or nylon suit holds warmth and moisture against the skin in exactly the spots you'd rather keep cool, which can feel clammy and stuffy. Looser is better.
• Dyes can run. Heavy sweating in a hot room can cause some cheaper or brightly dyed fabrics to bleed, staining a bench towel or the wood. Stick to colorfast, sauna-appropriate items.

None of these rule swimwear out — they just steer you toward a loose, metal-free, colorfast suit rather than your tightest competition one.

Cotton vs synthetic

If you're wearing anything beyond a towel, natural fibers beat synthetics in the heat. Loose cotton breathes, absorbs sweat and doesn't cling — a light cotton wrap or an old cotton tee is far more comfortable than performance synthetics designed to be worn in cool air while you move. Tight synthetic athletic wear is the worst choice: it traps heat and moisture, can feel suffocating, and some blends simply aren't made to sit in prolonged high heat. The rule of thumb is loose and natural over tight and technical. (The one great exception to "natural" being soft and breathable is wool on your head — more on that below, and it's worth the detour.)

Take off jewelry, glasses and your watch

Some things should come off before you step in, and metal is the theme. Jewelry: rings, necklaces, earrings and bracelets are metal, and metal conducts heat — in a hot sauna it can warm up enough to be genuinely uncomfortable or even leave a mark, so take it off. Watches and fitness trackers:most aren't rated for sauna heat and humidity; leave them in the locker to avoid damage (and don't rely on a wrist tracker's numbers in there anyway). Glasses: they fog instantly, and metal frames heat up — most people are more comfortable without them. Anything in your pockets:phones and cards don't belong in the heat at all. The pattern is easy to remember: if it's metal or electronic, it stays outside.

Why a wool hat helps in a hot traditional sauna

Here's the one that surprises people: in a hot traditional sauna, many regulars wear a wool felt sauna hat, and it's not a gimmick. Your head and scalp are sensitive to heat, and in a 170-190F room they can overheat before the rest of you is done — which is what cuts a lot of sessions short. A wool hat insulates the head, buffering it from the hottest air near the ceiling so you can stay in comfortably longer. Wool is the material of choice for a specific reason: it insulates effectively even when damp, so it keeps working as you sweat, where a cotton hat would just get wet and stop helping (The Woolmark Company documents wool's thermal-insulation and moisture properties). It's a traditional Finnish touch that earns its place. If you're curious which ones are worth it, our best sauna hats roundup covers the picks. Note the caveat: a hat is for hot traditionalsaunas — in a gentle infrared cabin at 120-140F, you simply don't need one.

Home vs public: the rules change

Where you are decides most of this. In your own home sauna, wear whatever's comfortable — a towel is the easy, hygienic default, and there's no dress code to read. In a public gym or mixed spa, swimwear or a towel is the norm and you should always sit on a towel over whatever you wear. In a traditional or European sauna, towel-only or nude (usually gender-separated) is common, and swimwear can even be frowned on as less hygienic — read the posted rules and watch the regulars. The safest universal move is to bring a towel everywhere: it works as clothing, as a seat cover, and as your fallback whenever you're unsure. How you dress is really one piece of the broader question of how to conduct yourself in a shared hot room, which we cover in full in our sauna etiquette guide.

Bottom line

Default to a towel; it's never wrong. Wear loose, natural, metal-free swimwear or cotton in mixed public settings, not tight synthetics. Take off jewelry, watches and glasses before you go in. Add a wool hat if you're doing hot traditional heat and want to stay in comfortably. And let the setting set the standard — home is relaxed, public means a towel plus swimwear, and traditional saunas have their own deeper norms. Get the material and the metal right, and what you wear stops being something you have to think about. For the rest of a great session, see our how to use a sauna guide.