What is löyly?

Löyly is a Finnish word with no direct translation.

It refers to the soft wave of heat that rises when water is poured onto hot stones in a sauna. More precisely, it describes how the heat moves through the space and how it is felt by the body.

In a Finnish sauna, löyly is central. Without it, the sauna is incomplete.

Löyly is not just steam

Löyly is often described as steam, but this is not fully accurate.

Steam suggests moisture alone. Löyly is about movement. It is the moment when heat lifts, spreads, and settles across the sauna room. When this movement is designed right, löyly feels round and enveloping rather than sharp or sudden.

You feel it on the skin, in the breath, and in the way the sauna space changes for a moment.

How löyly is created

Löyly is created when water is poured onto stones of the kiuas, the stove, that are fully heated.

For this to work properly, several conditions need to be met.

The stove must carry a sufficient mass of stones. The stones must be heated deeply, not just on the surface. And the sauna space must allow air to move in a controlled way.

When these elements are balanced, the water does not evaporate instantly. Instead, the heat, and löyly, rises slowly and evenly, filling the space before settling again.

The role of the stones

The kiuas stones are essential to löyly.

They store heat and release it gradually. A large stone mass allows the sauna to respond gently when water is added. Too few stones, or stones that are not fully heated, produce a thin and fleeting sensation.

In a Finnish stove, stones are chosen and arranged for function, not appearance. Their purpose is to hold heat and support löyly, session after session.

Air and space matter

Löyly depends on airflow as much as heat.

Fresh air must enter the sauna in a deliberate way. This supports breathing and allows heat to circulate naturally. When airflow is missing or poorly placed, löyly becomes heavy or uneven.

There should be an incoming air vent designed somewhere near the bottom of the kiuas, the stove. And an upper exhaust vent high on the opposite wall to remove stale, hot air. This will create a continuous, diagonal airflow for even heat and comfortable breathing in the sauna.

A well-built sauna allows the heat to move through the room and return gently, without pressure.

Löyly and temperature

Löyly is not about extreme temperatures.

In Finnish saunas, temperatures often sit around 70 to 80 degrees Celsius. At this range, löyly can be felt clearly without overwhelming the body.

The sensation of heat comes and goes with the water, rather than remaining fixed. This creates a rhythm in the sauna, where the heat changes over time instead of staying static.

A shared understanding

In Finland, löyly is understood through use rather than explanation.

People learn it by feeling when it is right. By noticing how the heat arrives and how it leaves. By adjusting how much water is used and when.

Because of this, löyly is rarely discussed in technical terms. It is recognised when it is present, and missed when it is not.

In a shared sauna, it is customary to ask before pouring water onto the stones. Löyly affects everyone in the room.

The person who pours the water remains seated while the löyly moves through the space. Leaving during löyly is considered impolite. The heat is shared, and so is the moment.

Why löyly matters

Löyly is what gives the Finnish sauna its character.

It softens the heat. It allows the body to stay longer. It turns a hot room into a space that feels alive and responsive.

Without löyly, heat becomes flat. With it, the sauna breathes.

At Lilla Sauna, our sauna is built to support good löyly.

From the wood-fired stove and stones to the airflow and bench height, every detail exists to allow heat to move as it should.