Buying Sauna Stones: A Quick Checklist
Buying sauna stones comes down to the right rock type, the right quantity and a good size mix. Here is a quick checklist to get it right the first time.
The short answer
To buy sauna stones well, get three things right: the right rock (dense, low-porosity igneous stone sold for saunas), the right quantity (your heater rated capacity), and a good size mix (large to small). Everything else is detail.
Sauna stones are cheap and easy to buy well — if you know the three things that matter. Here is the quick checklist.
1. The right rock
Buy stones sold specifically for saunas: dense, low-porosity igneous rock like olivine diabase or peridotite. Never substitute river stones or random rock, which can crack or burst.
2. The right quantity
Match your heater rated stone capacity — 10–20 kg for small electric units, 40 kg or more for wood stoves. Buy a little extra to discard misshapen pieces and keep a reserve.
3. A good size mix
Choose a mix of sizes: larger stones for the base, smaller for the top. Most sauna stones come in a suitable range, but check.
Quick checklist
| Check | Aim for |
|---|---|
| Rock type | Dense igneous, sold for saunas |
| Porosity | Low — no water-worn rock |
| Quantity | Heater rated capacity + a little spare |
| Size | A large-to-small mix |
| Condition | No visible cracks or layers |
Once you have them, rinse, stack loosely large-to-small, and fill to capacity. Good stones, well chosen and well loaded, are the cheapest route to a great löyly.
Where and how much to buy
Buy sauna stones from a sauna or heater supplier rather than a garden centre, so you know you are getting dense, low-porosity rock intended for the heat rather than unknown landscape stone. Sold specifically as sauna stones, olivine diabase and peridotite come in a size range suited to loading, and cost very little for a load that lasts years.
On quantity, buy a few kilograms more than your heater rated capacity. The extra lets you discard any misshapen or already-cracked pieces when you load, still fill to capacity, and keep a small reserve to top up the pile as stones degrade over time. That way you are never caught short mid-load or forced into a special trip when a few stones crumble. Get the right rock, the right amount with a little spare, and a good size mix, and the cheapest component of your sauna does a disproportionate amount to make the löyly soft and strong.
If you remember only one thing when buying, make it this: buy stones sold specifically as sauna stones, not landscape rock. That single choice guarantees dense, low-porosity stone that stores heat and resists cracking, and rules out the water-worn rock that can burst in a hot room. Add the right quantity with a little spare and a good size mix, and the cheapest part of your sauna is sorted.
Frequently asked questions
What should I look for when buying sauna stones?
The right rock (dense, low-porosity igneous stone sold for saunas), the right quantity (your heater rated capacity plus a little spare), and a good size mix from large to small.
How much should sauna stones cost?
They are inexpensive — a bag of proper sauna stones costs little and lasts years. There is no saving worth using unsafe random rock instead.
Where should I buy sauna stones?
From a sauna or heater supplier that sells stones specifically for saunas, rather than a garden centre. That ensures the right dense, low-porosity composition.
How much extra sauna stone should I buy?
A few kilograms beyond the rated capacity, so you can discard misshapen or cracked pieces on loading and keep a small reserve to top up as stones degrade.
Do sauna stones come in the right size?
They usually come in a suitable size range, but not pre-sorted. Sort them large-to-small before loading so you can build the pile correctly.
Where should you buy sauna stones?
From a sauna or heater supplier that sells them specifically as sauna stones, rather than a garden centre. That ensures dense, low-porosity rock intended for the heat, not unknown landscape stone that could crack or burst.
How much extra sauna stone should you buy?
A few kilograms more than your heater rated capacity, so you can discard misshapen or cracked pieces on loading, still fill to capacity, and keep a small reserve to top up as stones degrade over time.
Are sauna stones expensive?
No — they are inexpensive, and a load lasts years. There is no saving worth using unsafe random rock instead. Buy proper sauna stones, with a little spare, and load them well.
What is the most important rule when buying sauna stones?
Buy stones sold specifically as sauna stones, not landscape or river rock. That guarantees dense, low-porosity stone that stores heat and resists cracking, and rules out water-worn rock that can burst when heated.
