What Is a Sauna? Types, History and How They Work

So what is a sauna, exactly? At its simplest, a sauna is a heated room, usually lined with wood, designed to warm your body deliberately for relaxation, recovery and the sheer pleasure of the heat. That is where the simple part ends, because the word covers several quite different experiences, from the bone-dry heat of a traditional Finnish cabin to the gentle warmth of an infrared cabinet and the wet heat of a steam room. This guide explains what a sauna is, where the practice comes from, and how the main types differ, so you can tell which one you actually want.

A short history

The sauna is Finnish in origin, and it is genuinely ancient. Sauna bathing has been part of Finnish life for thousands of years, with the earliest examples dug into the ground and warmed by fire, and it remains central to the culture today, where a sauna is a place for washing, relaxing and socialising rather than a luxury add-on. From those roots the practice spread across the Nordic and Baltic world, each with its own version, and in the last few years it has taken off again in the UK, where public saunas, mobile barrel saunas by the sea, and the pairing of a cold dip with a hot sauna have all become popular. The British Sauna Society has helped drive that revival.

The traditional Finnish sauna

When people picture a sauna, this is usually it: a wood-lined room with a stove (called a kiuas) topped with a pile of stones. A wood-burning or electric heater warms the stones, which in turn heat the air to roughly 70 to 100°C. The defining ritual is löyly, ladling water over the hot stones to release a burst of steam that briefly lifts the humidity and makes the heat feel more intense on the skin. Between throws the air is fairly dry, with humidity typically sitting somewhere between 10 and 60 per cent depending on how much water you use. It is the hottest of the common types, and the control you have over the steam is a large part of the appeal. For a full comparison of this against the modern alternative, see our guide to traditional versus infrared saunas.

The infrared sauna

An infrared sauna is a 20th-century invention that works on a completely different principle. Instead of heating the air, infrared panels emit invisible infrared energy that your body absorbs directly, warming you from the surface inward while the cabin itself stays much cooler, usually around 45 to 65°C. Because the air is not as hot, many people find infrared easier to tolerate for longer, and the lower running temperature can mean lower energy use. What you lose is the ritual and the enveloping, steam-and-stone atmosphere of a traditional sauna. It is a different experience rather than simply a hotter or cooler one.

The steam room

A steam room is not strictly a sauna, but it is close enough to belong in the same conversation. Here the temperature is much lower, around 40 to 50°C, but the humidity is pushed to nearly 100 per cent, filling the room with visible steam. The heat reaches you as water vapour condenses on your skin, which is why a steam room can feel intensely hot despite the modest air temperature. Steam rooms are tiled rather than wood-lined, because the moisture would ruin timber, and they suit people who prefer wet, sinus-clearing heat to dry.

How they compare

The quick way to tell them apart is by what is being heated and how wet the air is:

• Traditional sauna: heats the air with hot stones, high temperature (70 to 100°C), dry with controllable bursts of steam.
• Infrared sauna: heats your body directly with infrared, lower cabin temperature (45 to 65°C), dry air.
• Steam room: heats you with near-total humidity, low temperature (40 to 50°C), very wet.

There is no single best answer. Traditionalists love the fierce, ritual heat of a Finnish sauna; people who find that too much often prefer infrared; and those who like moist heat go for steam. Many of the UK’s newer sauna venues, and a growing number of home setups, offer a traditional wood-fired or electric sauna precisely because the löyly experience is the one people travel for. If you are thinking of your own, our home sauna buying guide walks through the choices.

Beyond the sauna: banya and cold plunge

The heat is only half the tradition. In much of the Baltic and Slavic world the sauna is paired with a cold plunge, a lake, a bucket or an ice bath, and the hot-cold cycle is the whole point. The Russian and Eastern European banya adds high humidity and the famous venik, a bundle of leafy birch branches used to gently whisk the skin. Whichever tradition you follow, the core idea is the same: deliberate, enjoyable heat, usually followed by a cool down, as an old and remarkably durable way to relax.

Frequently asked questions

What is the difference between a sauna and a steam room? A sauna uses dry, high heat, typically 70 to 100°C in a traditional wood-lined room, with only brief bursts of steam. A steam room runs much cooler, around 40 to 50°C, but at nearly 100 per cent humidity, so it feels wet and misty. Saunas are lined with wood; steam rooms are tiled.

What temperature is a sauna? A traditional Finnish sauna runs roughly 70 to 100°C. An infrared sauna is cooler, around 45 to 65°C, because it heats your body rather than the air. A steam room is cooler still at about 40 to 50°C, but its very high humidity makes it feel hot.

Is an infrared sauna a real sauna? It is a modern type of sauna that heats you directly with infrared energy instead of heating the air with hot stones. It offers a gentler, lower-temperature experience but lacks the steam ritual of a traditional sauna, so which counts as the “real” one comes down to what you want from it.

Where does the sauna come from? The sauna is Finnish and thousands of years old, originally a fire-warmed room dug into the earth. It remains central to Finnish culture as a place to wash, relax and socialise, and the tradition has spread across the Nordic and Baltic regions and, more recently, enjoyed a strong revival in the UK.

What is löyly? Löyly is the Finnish word for the steam produced when you ladle water over the hot stones of a traditional sauna. It briefly raises the humidity and makes the heat feel more intense, and controlling it is a big part of the traditional sauna experience.