The five recommendations at a glance
| Product | Weight | Stone size | Special feature | Price range | Rating |
|---|---|---|---|---|---|
| Harvia Finnish diabase | 20 kg | n/a | for electric and wood-fired heaters | under €100 | 4,5/5 |
| Harvia sauna stones | 20 kg | n/a | Classic alternative | under €100 | 4,4/5 |
| Suleno olivine diabase | 20 kg | 8 to 10 cm | pre-washed according to the supplier | under €100 | 4,3/5 |
| WelaSol Premium olivine diabase | approx. 19 to 20 kg | n/a | checked and pre-washed according to the supplier | under €100 | 4,3/5 |
| Sauflex olivine diabase | 15 kg | 10 to 15 cm | rounded, for column heaters | under €100 | 4,2/5 |
The sauna stones in detail
Harvia sauna stones 20 kg Finnish diabase
- Diabase from Finland by the well-known heater manufacturer, matched to its own heaters
- Suitable for electric and wood-fired heaters alike, according to the supplier
- 20 kilograms cover many compact wall-mounted heaters with a single pack
- Rinse thoroughly before first use like any sauna stone, stone dust included
Harvia sauna stones 20 kg
- Established on the market for years, with correspondingly many documented user experiences
- Olivine diabase, the manufacturer's standard material, with good heat storage
- A reliable choice when the favourite set is currently unavailable
- No detailed size specification in the set; for column heaters, it is better to choose large stones specifically
Suleno olivine diabase 20 kg
- A stone size of 8 to 10 centimetres fits well into the stone chambers of common wall-mounted and compact heaters
- Pre-washed according to the supplier, which reduces stone dust and shortens preparation
- Dense olivine diabase with decent reserves for several steam rounds
- We recommend a short rinse before the first heat-up despite the pre-wash
WelaSol Premium olivine diabase
- Checked and pre-washed according to the supplier, so you can layer them in faster
- Set established for years with a broad user base in German-speaking countries
- Olivine diabase stores heat reliably for rich steam during the infusion
- The weight of around 19 to 20 kilograms varies slightly depending on the pack
Sauflex olivine diabase 15 kg rounded
- Large, rounded stones of 10 to 15 centimetres form stable, airy columns
- Ideal for column heaters with a large stone volume, where small stones pack too densely
- The rounded shape lets air circulate and makes loose layering easier
- At 15 kilograms per sack, you need several packs for large column heaters
Why olivine diabase is the standard
Sauna stones live in a brutal rhythm: they are heated to several hundred degrees for hours and then suddenly quenched with cold infusion water. In the long run, only a dense, fine-grained plutonic rock can withstand that. Olivine diabase from Scandinavian quarries has therefore become the standard: it absorbs hardly any water, does not burst when quenched and stores heat long enough to answer several infusions in a row with rich steam.
Porous or calcareous stones from the garden, by contrast, are a safety risk: trapped moisture can blast off splinters when heated, and crumbly rock disintegrates into the stone chamber. That is why the rule is: use only stones designated as sauna stones, if in doubt from the heater manufacturer itself. The Harvia sets made of Finnish diabase are the obvious choice here, the pre-washed sets from Suleno and WelaSol the convenient one.
The stone is, by the way, only half the battle for the sauna climate: how much steam ultimately reaches the cabin is decided by heater output and infusion technique together. You will find suitable heaters in our sauna heater overview, and the rest of the extras from the ladle to the thermometer in the accessories section.
Stone size: wall-mounted heater or column heater?
Compact wall-mounted heaters, as are common in home saunas, have flat stone chambers above the heating elements. Medium-sized stones work best here, such as the 8 to 10 centimetres of the Suleno set: small enough for the chamber, large enough for air in between. Which compact heaters manage without a heavy-current connection is shown in our comparison of 230-volt sauna heaters.
Column heaters are the opposite: tall stone baskets with a volume of 40, 60 or more kilograms, through which air flows from bottom to top. Small stones pack too densely here and choke the circulation. Large, rounded stones such as the 10 to 15 centimetres of the Sauflex sets, on the other hand, form stable, airy columns; that is exactly what they are made for.
Layering sauna stones correctly
The golden rule is loose rather than stuffed. Rinse the stones, sort them roughly by size and place the largest ones at the bottom. The medium ones follow on top and the smaller stones right at the top, always so that air can circulate between them. With electric heaters, the heating elements must be completely surrounded by stones, without you pressing stones in between the elements: wedged pressure can damage heating elements as they expand.
If you stuff the chamber, you pay twice: the heater takes longer to heat up because the air does not circulate, and the infusion fizzles out instead of rising as steam. A loosely layered heater sounds audibly different during the infusion: the water hisses down through several layers of stones instead of evaporating only on the top layer.
Care and replacement
Before first use, all stones are washed thoroughly with clear water, including the sets from Suleno and WelaSol that are pre-washed according to the supplier; cleaning agents stay in the cupboard. After that, an annual inspection is enough: take the stones out, remove fragments and rock dust, and layer the rest in again, new and loose. When rearranging, you see immediately which stones have become cracked or crumbly.
As a general recommendation, not a manufacturer requirement: with regular use of one to two sauna sessions per week, one to two years has become established as a replacement interval. Frequent sauna-goers replace them sooner, occasional users later. At the latest when stones crumble to the touch or the infusion becomes weak despite a hot heater, replacement is due. How the perfect infusion succeeds afterwards is shown in our infusion guide, and you will find matching scents in the comparison of sauna infusions.
How many stones your heater needs
The only binding source for the stone quantity is your heater's manual: the manufacturer states how many kilograms the chamber holds, and this specification beats any rule of thumb. As rough guidance: compact wall-mounted heaters are often at 15 to 25 kilograms, so a single 20-kilogram sack from Harvia, Suleno or WelaSol often covers them. Column heaters swallow a multiple of that depending on the model; here you plan for several packs from the start.
Better to allow for one pack more than one too few: leftover stones are the perfect supply for the next replacement. This applies especially to saunas with powerful heaters such as the barrel sauna in the garden, whose column heaters hold significantly more stone mass than compact indoor heaters.
Conclusion
Sauna stones are the cheapest component of your sauna and at the same time one of the most important: without dense, correctly layered stones, even the best heater stays below its potential. You can't go wrong with the Harvia sets made of Finnish diabase, Suleno and WelaSol save you preparation time, and column heater owners reach for the large Sauflex stones. Check once a year, layer loosely, replace in good time, and the infusion will thank you at every sauna session.