Guidelines for sauna sizing

The most important thing when sizing your sauna is to start with your own needs. If you are planning a sauna for yourself or your family, even a smaller sauna will do. If you are planning to use the sauna with a larger group, you will need more space.

There are limits to the size of a sauna, which should be used when designing a sauna. Rakentaja.fi-website, you can find, for example, the following approved limit values. You can also find more information on requirements for thermal insulation in saunas, among other things.

• The height of the sauna room should be 2000-2200 mm (an unnecessarily high sauna consumes unnecessary energy)
• One person should be allowed at least 600 mm of board length
• The depth of the seat should be 450-900 mm (narrower for sitting and wider for lying down)
• The depth of the footplate should be 300-400 mm
• The space between the seat and the roof should be 1000-1200 mm
• Floor space should be about 1 m² per person

Effect of heater type on sauna sizing

When sizing your sauna, it is important to consider the type of heater you choose for your sauna. Electric sauna heaters and wood heater differ in terms of both space requirements and practical features. Wood-burning heaters requires more space, for example due to safety distances, while an electric heater allows for a more compact sauna that can be heated quickly. The choice of heater therefore strongly influences the size and dimensioning of the sauna.

• An electric heater is often a more compact option in terms of space. Its safety distances are usually shorter than those of a wood heater, and it usually heats up more quickly. Electric heaters are particularly suitable for smaller saunas, as long as the power is correctly sized for the volume. It is also worth bearing in mind that if the sauna has a lot of glass surfaces or heat-retaining materials, additional power may be needed.
• A wood-burning heater needs plenty of air to burn properly, so you need efficient ventilation. In addition, for fire safety, larger safety distances are left around the heater, which in practice increases the minimum size of the sauna. Wood heaters also heat up more slowly, so in larger spaces they may require more time and firewood to reach a comfortable temperature. On the other hand, it offers the traditional sauna experience of wood smell, soft suds and authentic warmth.

Read also: Sauna renovation ahead? How to design a successful sauna

Sauna size - volume and calculation of cubic metres

When designing a sauna, it is important to determine the volume. The size of the sauna, i.e. the cubes, determines, among other things, the power of the heater required. The right size of heater ensures that the sauna heats energy efficiently and provides a pleasant sauna experience without unnecessary consumption.

When determining the power requirement of a heater, in addition to the cubic volume of the sauna, you also need to consider surfaces that absorb heat, such as glass and stone surfaces. By taking into account the effect of these surfaces, the effective volume of the sauna can be determined. Only on the basis of the effective volume can the right heater be selected for the sauna. In borderline cases, it is advisable to choose a slightly more powerful heater. Our heater calculator also take into account the effective volume of the sauna.

The volume is calculated using a simple formula:

length × width × height = volume of sauna (m³)

For example 1,5 m × 2,0 m × 2,0 m = 6 m³

Guidelines on sauna volumes for different numbers of users

• Double sauna
  • A small and compact sauna, usually around 6 m³, is sufficient for two people. There is room for two to sit in a sauna, but lying down and enjoying a sauna can be a bit cramped. The heater power requirement is around 6 kW, depending on the materials used in the sauna and any glass surfaces.
  • Mondex 6 kW and 6.6 kW models are suitable for small saunas. Read more about heaters suitable for small saunas!
• Sauna for four persons
  • A family of four or a small group of friends will need a slightly larger sauna. A suitable volume is around 8-10 m³. This allows four people to sit comfortably on the benches and also leaves room for feet. The heater power requirement is usually around 8-9 kW, and the sauna should be designed with sufficient depth in mind.
  • Many of Mondex's small 6.6 kW heaters are sufficient for saunas up to 9 m³ and the medium sized 9 kW heaters up to 15 m³.
• Sauna for six persons
  • For example, a sauna for six people can have a volume of 15-20 m³. Such a sauna has room for more people to sit and often also has the option of lying down to take a sauna bath. A larger size requires a more powerful heater, for example 10.5 kW.
  • Mondex's largest 10.5 kW heaters are easily sufficient for larger saunas. For example Tahko 22 m³ is sufficient and Rakka up to 25 m³.

Sauna dimensions and heater safety distances

When designing a sauna, it is also a good idea to consider the safety distances of the heater. Safety distances are the space that must be left between the heater and the sauna's structures, such as walls, roof and ceilings. They ensure that surrounding materials are not overheated and that the sauna remains safe to use.

The safety distances vary depending on the model of heater, so you should always check the instructions for the stove. For wood heaters, they are usually larger than for electric stoves, so the choice of the final heater model will also affect how you should plan the space and the dimensions of the sauna. This will ensure that the sauna is not only functional and comfortable, but also safe and ready to receive the heater you choose. Read more about the safety distances of the heater!

The right heater completes the sauna experience

The size and dimensions of the sauna have a decisive influence on the sauna experience. By designing the sauna to meet the needs of its future users, choosing the right heater and considering safety distances at the design stage, the sauna will perform at its best. A properly sized sauna is energy efficient, safe and provides the best possible sauna for a couple, a family or a large group.

The Mondex range of heaters offers options for saunas of different sizes and designed for different uses. Take a look at the heaters and choose the right solution for your sauna - ensuring a successful sauna experience for years to come!