Sauna heater size calculator: how to choose the right power rating for your sauna is an essential question when building your sauna.
You need to make many important decisions when constructing a sauna. Among other things, you must choose a proper sauna heater.
How the Size and Construction of Your Sauna Room Affect Heater Power Selection
The size and construction of the sauna room affect the choice of heater power.
The heater’s power requirement increases if the sauna room has glass windows or doors and heat-retaining brick, concrete, or log wall surfaces.
Choosing the wrong heater can ruin the entire sauna experience: the steam might be too weak or, on the other hand, too intense.
Sauna Heater Size Calculator: A Useful Tool to Help You Choose the Right Heater Power and Model
A Sauna Heater Size Calculator is a useful tool that assists you with calculations and helps to choose the power rating and model of the heater that suits your sauna.
By entering the parameters of your sauna room, the calculator will provide you with the appropriate heater power and model for your sauna.
It Is Important to Remember That More Power Doesn’t Always Mean Better Steam
It is important to remember that a more powerful heater does not necessarily provide better steam. Saunas are different, and the characteristics of the steam room must be taken into consideration when choosing the heater.
All Massive Wall Surfaces of the Sauna Should Be Insulated to Ensure Proper Heater Performance
All massive wall surfaces of the sauna where heat accumulates should be insulated to utilize the optimum capacity of the heater.
When this is not possible, a higher power rating is necessary to ensure that the heater warms up the non-insulated surfaces (e.g., glass doors or log walls) and compensates for the heat loss. Therefore, heater selection cannot only be based on the size of the steam room, and the calculated cubic size VA must also be considered.
This Article Explains How to Calculate Sauna Heater Capacity and Key Considerations for Selecting the Right Heater
This article explains:
- the calculation formula that enables one to determine the capacity of a suitable sauna heater
- most important considerations that apply to selecting a proper heater
Sauna Heater Size Calculator is a useful tool that assists you with calculations and helps to choose the power rating and model of the heater that suits your sauna. HUUM sauna calculator is available here:
Criteria for Adequate Sauna Insulation
The criteria for adequate sauna insulation involve ensuring that the sauna’s walls and ceiling are built with effective thermal insulation and vapor barriers. Proper insulation minimizes heat loss, maintains steady temperatures, and allows the sauna heater to operate at its optimum capacity.
Well-insulated walls and ceilings are essential for an energy-efficient and comfortable sauna experience.
The following sauna wall and ceiling construction is considered to be sufficiently insulated:
- the carefully installed insulation layer of 100 mm (4 in), minimum 50 mm (2 in);
- moisture barrier of the construction is established with taped aluminum foil or another reflective material;
- there is at least a 10 mm (0.4 in) air gap between the moisture barrier and the clapboard;
- a light wooden board with an approximate thickness of 12–16 mm (0.5 – 0.65 in) has been used for interior finishing;
- there is at least a 5 mm (0.2 in) air gap on the boundary of the ceiling panels at the upper part of the wall boards.
In order to optimize the capacity of the sauna heater, it would be beneficial to make the ceiling of the sauna lower, which reduces the cubic size of the steam room (the normal height of the sauna is 2100-2300 mm (83-91 in), minimum height is 2000 mm (75 in).
Insulation of the ceiling must be at least 100 mm (4 in) thick, and the ceiling should be lined as described above.
Calculated cubic size of the steam room
Calculated cubic size of the steam room (VA) is calculated by adding the additional volume of non-insulated surfaces (a glass door or a glass wall, a non-insulated wood or log wall) (VS) to the cubic meter/feet of the room (VR).
In order to determine the additional volume of non-insulated surfaces (VS), multiply the square feet/meter of non-insulated surfaces (S) by the corresponding coefficient (k).
Non-insulated surface |
Coefficient (k) |
| Glass, log wall or other non-insulated surface | 1 (metric) |
| 3.3 (imperial) |
To obtain the actual cubic size of the steam room (VR), multiply its length (a) by width (b) and height (h).
VR = a x b x h
In order to determine the square meters of non-insulated surfaces (S), multiply the edges of the non-insulated surface plane.
S = a x b
Then multiply the square meters of non-insulated surfaces (S) by the coefficient (k) that depends on the material of the non-insulated surface. This gives you the additional volume of non-insulated surfaces (VS).
VS = S x k
In order to obtain the calculated cubic size of the steam room (VA), add the additional volume of non-insulated surfaces (VS) to the actual cubic size of the room (VR).
VA = VR + VS
One calculated cubic meter presumes one kilowatt of the heater’s power. Choose a sauna heater that has the closest capacity.
1 m³ A = 1 kW (metric)
35³ ft A = 1 kW (imperial)
Examples of the calculations (metric system)
For example, if your steam room is 2 meters long, 1.8 meters wide and 2.2 meters high, you’ll get the cubic size of the room by multiplying these figures.
VR = 2 x 1.8 x 2.2 = 7.92 m³
Let’s presume that the steam room has a glass surface (a glass wall with a door) that is 1.8 meters wide and 2.2 meters high.
Square meters of the non-insulated surface are determined as follows:
S = 1.8 x 2.2 = 3.96 m²
We must multiply this result by the corresponding coefficient (1).
VS = 3.96 x 1 = 3.96 m³
Finally, we should add the additional volume of non-insulated surfaces to the actual cubic size of the room, in order to obtain the calculated cubic size of the steam room.
VA = 7.92 + 3.96 = 11.88 m³
You should choose the sauna heater on the basis of the calculated cubic size 11.88 m³, and not the actual cubic size 7.92 m³.
As you can see, non-insulated surfaces have a significant impact on suitable heater options. Non-insulated surfaces account for over 40% of the required capacity.
Examples of the calculations (imperial system)
For example, if your steam room is 7 feet long, 5 feet wide, and 7 feet high, you’ll get the cubic size of the room by multiplying these figures.
VR = 7 x 6 x 7 = 294 ft³
Let’s presume that the steam room has a glass surface (a glass wall with a door) that is 6 feet wide and 7 feet high. The area of the non-insulated surface is determined as follows:
S = 6 x 7 = 42 ft²
We must multiply this result by the corresponding coefficient (3.3).
VS = 42 x 3.3 = 139 ft³
Finally, we should add the additional volume of non-insulated surfaces to the actual cubic size of the room, in order to obtain the calculated cubic size of the steam room.
VA = 294 + 139 = 433 ft³
You should choose the sauna heater on the basis of the calculated cubic size 433 ft³, and not the actual cubic size 294 ft³.
As you can see, non-insulated surfaces have a significant impact on suitable heater options. Non-insulated surfaces account for over 40% of the required capacity.
Wood-burning stoves
After the calculations, compare the results with the specifications of the heater manufacturer when you start choosing the sauna stove that matches the calculated cubic size of the steam room.
It is reasonable to add some reserve, as it is not recommended to heat the sauna stove constantly at full power. Unlike electric sauna heaters, a wood-burning stove enables one to vary the heating power.
Constant intensive heating shortens the useful life of the stove remarkably. When the sauna reaches the desired temperature, just a few logs should be used to keep the furnace hot.
At the same time, the wood-burning stove should not be excessively powerful. If the stove is too powerful, the room heats up quickly, but sauna stones are not hot enough to add steam. In the case that you continue heating, the steam room will be overheated by the time the sauna stones obtain sufficient temperature.
Electric sauna heaters
Before deciding on a particular electric sauna heater model, an electrician should determine the parameters of the main circuit breaker and the cross-section of the power cable.
In the case that your power system does not enable you to mount a heater that has the required capacity, opt for a heater that holds more sauna stones.
A larger amount of stones stores more energy and vaporizes more water, and hence compensates for the output shortage of the sauna heater. Heating the sauna takes more time, but ensures a more satisfactory sauna experience.
Determining the proper capacity of the sauna heater is an important part of building a sauna. The excellence of sauna sessions depends on a variety of factors. One significant yet often neglected aspect is ventilation. Learn more about sauna ventilation.
