Löyly (roughly "LEU-lu") is the wave of steam and heat that rises when water hits hot sauna stones. In Finnish the word also covers the water you throw and the overall quality of a sauna's heat, which is why Finns don't ask how hot a sauna was; they ask how the löyly was (Sauna from Finland). If you have only used gym or infrared saunas in North America, there is a fair chance you have never felt it: the sign on the wall forbids water, the cabin has no stones, or the stones never get hot enough.
By Fuentes, founder of Lanoviss · October 2026
What does löyly mean in Finnish?
Three things at once. Löyly is the steam itself; it is also the water, so "Heitä löylyä" ("throw some löyly") is a request for another ladle; and it is the verdict, so leaving a sauna with "Olipa hyvät löylyt!" ("What great löyly!") is the best review a sauna can get (Sauna from Finland). English usually translates it as "steam", which that same Sauna from Finland article calls "slightly erroneous": technically right, missing most of it.
The word is everyday Finnish, not ceremony. One sauna-stone brand is literally called Parhaat Löylyt, "the best löyly", and the Finnish hardware chain K-Rauta sells Harvia stones under the line "kiuaskivet varmistavat hyvät löylyt": the stones that guarantee good löyly (Sauna from Finland, K-Rauta).
| Finnish | What it means |
|---|---|
| löyly | The steam off the stones; the water thrown; the quality of a sauna's heat |
| kiuas | The sauna stove or heater |
| kiuaskivet | The stones on the stove |
| Heitä löylyä | "Throw some löyly": please add water |
| Olipa hyvät löylyt! | "What great löyly!": the sauna was good |
Where does the word löyly come from?
From an old word for breath and spirit. It descends from Proto-Finno-Ugric *lewle, the same root as Hungarian lélek, "soul", and Estonian leil, which we traced in the piece about our old name. In old Finnic belief, as the Finnish sauna writer Miika Vanhapiha explains, löyly was also one of a person's three souls: the life force that keeps the body warm and leaves it at death (Finnmark Sauna).
What makes good löyly?
Hot stones, enough of them, and not much water. Sauna from Finland lists the variables as the size of the heater, the amount of stones and how they are stacked, how much water is thrown and how often, and the air circulation in the room (Sauna from Finland). Each one fails in a way you can feel.
| What goes wrong | What you notice | Why |
|---|---|---|
| Stones not hot enough | Water hisses and runs straight through the stone basket; little steam | The air heated faster than the stones. Harvia's fixes: lower the set temperature, check the heater isn't oversized, check ventilation (Harvia) |
| Too much water at once | A cool, clammy cloud; boiling water can spit back | Only part of it evaporates. Harvia caps the ladle at 0.2 litres (Harvia manual; Wikipedia) |
| Stones packed tight, or too few | Short, sharp bursts that die quickly | Too little surface and mass. Small stones go on top, where they vaporise water best, and all stones sit loosely so air can move (Sauna from Finland) |
| Worn-out stones | Weaker, shorter steam | Stones break down with repeated heating and steaming; with daily use for hours at a time, replace them at least once a year (same source) |
| Wrong spot | A harsh bite instead of a soft wave | Top stones give a sharper sensation, lower stones softer steam (Sauna from Finland) |
Stone mass is the variable most people never think about. The Finnish Sauna Society notes that heat-storing wood heaters carry anything from a few dozen to several hundred kilos of stones, and the big heaters at its own Vaskiniemi saunas in Helsinki hold about one tonne (Finnish Sauna Society).
What does one ladle of water actually do?
More to you than to the thermometer. Take one throw as Harvia's 0.2-litre maximum: 200 g of water. If all of it evaporates and mixes evenly into a 10 m³ sauna (about 2 × 2 × 2.5 m), it adds 20 g of water vapour to every cubic metre of air.
Air at 80 °C can hold about 291 g/m³ before it saturates, and air at 90 °C about 419 g/m³ (from the saturation vapour pressure of water: 47.4 kPa at 80 °C, 70.1 kPa at 90 °C; reference values). So one ladle raises relative humidity by roughly 7 percentage points at 80 °C and 5 points at 90 °C. In a small 6 m³ home sauna at 80 °C, the same ladle is worth about 11 points. That is our arithmetic, not a measurement.
In practice the wave that reaches you is bigger and briefer than that average, because the steam climbs to the ceiling and rolls down over the top bench before it mixes.
Those points matter. In a 2026 University of Jyväskylä study, 50 healthy adults sat four 10-minute rounds in a Finnish sauna, free to throw löyly; average heart rate rose from 79 to 121 bpm during a 10-minute round, and humidity pushed it up independently of temperature, by about 0.37 bpm per percentage point of humidity against 1.40 bpm per degree (Laatikainen-Raussi et al., Temperature, 2026; University of Jyväskylä). On that scale about 3.8 points of humidity load the heart like 1 °C of air, so a 7-point ladle works out, as a rough estimate, to nearly 2 °C. Harvia provided the saunas for the study, which the authors disclose.
Why can't you throw water in most gym saunas?
Because many are run as dry rooms by rule. The University of New Orleans' campus fitness-centre sauna is typical: its posted guidelines say "Do not add water to rocks" (UNO). Follow the sign. Only a heater built to hold sauna stones should ever get water, and you can't tell from the bench how that one was specified (SaunaSpa).
Infrared cabins can't make löyly at all: there are no stones, and the emitters heat your skin rather than the air, as we explain in sauna vs banya vs steam room vs infrared. And a heater with a light load of stones can bring the air to temperature long before the stones are ready, which produces exactly the failure Harvia describes: water that "does not vaporise and runs through the stone compartment."
That is the sense in which löyly is the word your sauna is missing. The room may be hot, but the thing Finns actually judge a sauna by never happens in it.
How do you throw löyly properly?
- Ask the room first. A ladle changes the heat for everyone, and most of all for whoever sits highest; see sauna etiquette for your first time.
- Let the stones catch up. If the thermometer says 80 °C but the water runs straight through, the stones aren't ready. SaunaSpa, a Quebec sauna builder, says that in many of its installations that means waiting another 15–20 minutes after the air reaches temperature (SaunaSpa).
- Use the ladle, not the bucket: no more than 0.2 litres per throw (Harvia manual).
- Pour gently and let it fully evaporate before the next one. One or two ladles every few minutes is plenty (SaunaFin).
- Aim low for a soft wave, high for a sharper one.
- Never throw water when someone is standing near the heater. Water that doesn't evaporate can splash off the stones as boiling water, Harvia warns.
Where does a sauna hat come in?
Löyly reaches your head first. Steam rises to the ceiling and rolls down over the top bench, in a room where the air at face height already runs 80–100 °C while the floor sits near 30 °C (sauna temperature at head height). That is the moment people reach for a felt hat, which is standard kit in the Russian banya and increasingly common in Finland.
A wool hat doesn't cool you, and no controlled study has measured how much it helps; do sauna hats actually work? goes through what is and isn't known. What 3 mm of pressed merino felt does is slow how fast the hottest air reaches your scalp and ears. If you like big löyly, the Lanoviss merino wool sauna hat is $59.99 CAD, or $173.99 for all five colours.
Frequently asked questions
How do you pronounce löyly?
Roughly "LEU-lu", in two syllables. The "ö" is close to the vowel in French "peu" and the "y" to the vowel in French "tu"; both are said with rounded lips.
Is there an English word for löyly?
Not really. "Steam" is the usual translation, but löyly also means the water thrown on the stones and the quality of a sauna's heat, which is why Sauna from Finland calls the translation slightly erroneous.
How much water should you put on sauna stones?
One ladle at a time, no more than 0.2 litres, which is the maximum Harvia specifies for its heaters. Let each ladle evaporate completely before the next; one or two every few minutes is plenty.
Why does water on the stones make the sauna feel hotter when the thermometer barely moves?
Because the humidity changes, not the air temperature. Moist air slows the evaporation of sweat, your main way of shedding heat, and a 2026 University of Jyväskylä study found that humidity raises heart rate and core temperature independently of temperature.
Can you throw water on an infrared sauna?
No. Infrared cabins have no stones and their emitters are not designed for water. Only throw water on a heater built to hold sauna stones, and only where the venue allows it.
What does "Olipa hyvät löylyt" mean?
"What great löyly!" It is what Finns say on leaving a sauna they enjoyed. "Heitä löylyä", "throw some löyly", is how you ask for another ladle of water on the stones.
Is löyly the same as Aufguss?
No. Löyly is steam you make yourself, one ladle at a time. Aufguss is a German ritual in which a sauna master pours scented water on the stones and whirls a towel to push the heat around the room; sessions usually last about 15 minutes and run on an hourly schedule (Wandering Carol).
Fuentes is the founder of Lanoviss, which makes one product: a seamless 100% merino wool sauna hat, pressed from a single piece of 3 mm felt and shipped from Vancouver, British Columbia. Every external claim on this page links to its source; the humidity figures are our own arithmetic and are labelled as such. More about who makes it and why.
Related reading: is Saunatar a real Finnish goddess? · sauna temperature at head height · sauna etiquette for your first time