Sauna Stones Calculator: How Many Kg of Stones Do You Need?
Sauna stones do the real work: they store the heater's energy and release it as a soft, even heat, and they turn a ladle of water into löyly. Too few and the heat feels harsh and thin; pack them too tightly and you choke the airflow. This calculator turns your heater power or wood-stove size into a sensible stone weight, then tells you how many boxes to buy. Treat the figures as a guide: always follow the stone capacity printed on your own heater if it differs.
Your heater
Electric heaters need roughly two to three kilograms of stones per kilowatt to fill the element basket, so a 6 kW heater takes somewhere around 12 to 18 kg. Wood-burning stoves hold a lot more because the whole firebox is wrapped in stone, which is why their figures jump. The exact number is set by the size of your basket, so if the manual gives a stone capacity, use that and buy to the nearest box above it.
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