Sauna Heater Sizing Guide: Heat Your Haven Right!

Photo of author
Written By Lalabrothers

Lorem ipsum dolor sit amet consectetur pulvinar ligula augue quis venenatis. 

When it comes to a comfortable and secure sauna session, choosing the proper size sauna heater is key. You want your sauna room to hit that preferred temperature without any fuss. The size of your sauna plays a big part in this. You need to measure the volume of your sauna room in cubic feet to start. There’s a general rule of thumb we sauna lovers follow: 1 KW of power is needed for every 50 cubic feet of space. This helps ensure the desired temperature is reached and maintained.

But, it’s not just about the size. The type of sauna you have, like an infrared sauna or a standard sauna, makes a difference too. Infrared saunas heat the things in the room – like the walls and benches, not just the air. So, you might get away with a smaller heater and use less energy, which is great for both the environment and your wallet. Plus, the health advantages of saunas are well-documented in research, especially those torsional saunas without infrared. Getting an appropriately sized heater installed safely is crucial. Always consult a professional for a safe installation. They know all about these important considerations and can ensure everything’s set up just right for your peace of mind.

Sauna Heater Sizing Chart

Sauna Heater Sizing Guide: Heat Your Haven Right!

When setting up your sauna room, the size of the heater you choose is super important. You gotta think about the cubic volume of your sauna and how much air space needs to be heated. If your sauna is outside, you might need a larger heater, especially during the winter months. For safety purposes, heaters in North America have a max high limit temperature set at 194 F or 90 C, but in European countries, it might be higher. The size of your heater affects how quickly your sauna can heat up and how fast it can get back to the desired temperature if you add water to the sauna rocks. A bigger sauna heater can make more steam and get back to the right temperature faster than a smaller one. But all heater elements are pretty much the exact same size inside, whether it’s a 3 Kw or a 5 Kw heater. The general rule of thumb is you need 1 Kw for every 50 cubic feet of your sauna. So, for a room that’s 5.5′ x 5′ with a 7′ ceiling (that’s about 192.5 cubic feet), you’d look at getting at least a 4 Kw heater. Always better to round up to the next size to make sure you’ve got enough heat.

Sauna Room Size (Cubic Feet)

Recommended Heater Size (KW)

Max Temp (F/C)


Up to 2502 – 5 KW194 F / 90 CIdeal for smaller, possibly indoor saunas. Consider larger heaters for outdoor use in winter.
251 – 5006 – 10 KW194 F / 90 CSuitable for medium-sized saunas; recovery rate and steam generation are better with larger heaters.
501 – 75011 – 15 KW194 F / 90 CFor larger saunas; ensure proper insulation to maintain efficiency.
751 – 100016 – 20 KW194 F / 90 CLarge outdoor or commercial saunas require powerful heaters for optimal heat up and recovery times.
1001 – 125021 – 25 KW194 F / 90 CVery large saunas may need custom solutions; consult a professional.


SaunaCore™ Residential Heater Size

For SaunaCore™ heaters, they come in different KW sizes – 2, 3, 4, and 5. The Amps 240 VAC they use varies too – 9.6 for the 2KW, 14.4 for the 3KW, 19.2 for the 4KW, and 24.0 for the 5KW. The Wire Size needed changes as well – #14 for the smaller ones, #12 for the middle, and #10 for the biggest. And these heaters can warm up different Room Volumes – from 100 cubic feet all the way up to 250 cubic feet. This info helps make sure your sauna gets just the right heater to keep you toasty.

Heater Size (KW)

Amps 240 VAC

Wire Size

Suitable Room Volume (Cubic Feet)

2 KW9.6#14Up to 100
3 KW14.4#14100 – 150
4 KW19.2#12150 – 200
5 KW24.0#10200 – 250

Importance Of Matching Heater Size With Sauna Volume

For a well-matched heater to work right, it needs to fit your sauna volume. If it’s too small, it’ll struggle to keep up and won’t maintain those optimal temperatures you love. But a too-big heater? That could cause overheating and energy waste – yikes! You want even heat distribution in your steamy sanctuary, so the size has to be just right.

The Role Of Ceiling Height In Heat Distribution

Now, let’s talk about ceiling height. All sauna enthusiasts know that heat rises. So, a higher ceiling means there’s more space for hot air to accumulate. This is big news when you’re selecting your heater size. You gotta make sure your sauna has even temperature all over the room. And don’t forget about proper ventilation and maybe adjusting those bench heights to get it all nice and cozy. With this knowledge, you’re all set and ready to pick the perfect sauna heater.

When you’re looking at heater sizing, there’s a general table that shows what works for different sized outdoor saunas. It goes like this: For a sauna room size of 50-250 cubic feet, a 2-5 KW heater is good. And it goes up from there. The general rule of thumb is you need 1 KW of power for every 50 cubic feet of space to hit that desired temperature. Whether it’s an infrared sauna or a standard sauna, this rule helps. Always consult a professional before you make your final decision. They know what’s up and can help you out.

Outdoor & Uninsulated Sauna Considerations

Sauna Heater Sizing Guide: Heat Your Haven Right!
Source of image: Istockphoto

If your sauna room is uninsulated and located outdoors, you need a larger heater. Why? Because outdoor saunas get cold from wind and other elements. Without insulation, heat gets lost through walls, floor, and roof. You might need to increase heater size by 25-30% for it to work well. Let’s say you have a 500 cubic feet indoor sauna room that uses a 10 KW heater. For the same outdoor uninsulated sauna room, you might need about 13-13.5 KW. There’s a table that shows recommended sauna heater size based on sauna room size in cubic feet. It helps to add an additional 25% increase to the heater size for outdoor saunas. Always consult a professional before you make your final decision on the right size sauna heater.

Saunas With Lots Of Glass

Sauna Heater Sizing Guide: Heat Your Haven Right!
Source of image:Istockphoto

Saunas with a lot of glass are susceptible to heat loss. Glass windows let heat escape, making it hard to retain heat. You might need a larger heater or even more heaters to maintain the desired temperature. To compensate for this, consider a heater with higher wattage or a more powerful heater. You could also think about adding insulation to the glass or using a heat-retaining film. Another idea is a sauna controller that can adjust temperature and timing based on the heat loss. This helps to keep energy consumption at a minimum. When choosing the right size for an outdoor uninsulated sauna with lots of glass, remember the added heat loss. It’s a good plan to consult with a professional to determine the specific requirements for your sauna to make sure it’s appropriate for your needs.

How To Select A Sauna Heater With A Proper Power Rating?

When constructing sauna, one of the most important decisions is picking the proper sauna heater. You might choose an electric sauna heater or a wood-burning sauna stove. The goal is to determine capacity and calculate power rating that’s just right for your steam room. This is to prevent excessive heating or insufficient temperatures. It’s easy to underestimate the capacity sauna heater needed, but getting it right means better steam and a more enjoyable experience.

Sweat Smart: Sauna Use (Quick Guide!)

The characteristics of your steam room matter a lot in choosing heater. Massive wall surfaces should be insulated to use the heater at its optimum capacity. If not, a higher power rating might be necessary to warm up non-insulated surfaces like glass doors or log walls and compensate for heat loss. Your heater selection should match the size of steam room and calculated cubic size VA should be considered too.

What Are The Criteria For Adequate Insulation?

A sauna is sufficiently insulated when it has a good sauna wall and ceiling construction. An installed insulation layer of at least 100 mm (4 in), or at a minimum of 50 mm (2 in), is a good start. A moisture barrier made of taped aluminum foil or another reflective material helps too. Make sure there’s a 10 mm (0.4 in) air gap between the moisture barrier and the clapboard.

Sauna Thermometers for 2024: Best Choices and Where to Put Them

For the inside, a light wooden board with a thickness of 12–16 mm (0.5 – 0.65 in) is ideal for interior finishing. And don’t forget about a 5 mm (0.2 in) air gap at the boundary of the ceiling panels and the top of wall boards. This setup helps to optimize capacity of your sauna heater. A lower ceiling also reduces the cubic size of your steam room, making it easier to heat. The normal height for a sauna is between 2100–2300 mm (83-91 in), with a minimum height of 2000 mm (75 in). Make sure your ceiling insulation is at least 100 mm (4 in) thick and is lined properly for the best experience.

What Are The Criteria For Adequate Insulation?

To make sure your sauna is sufficiently insulated, check the sauna wall and ceiling construction. You need a good installed insulation layer of at least 100 mm (4 in), but 50 mm (2 in) can work too. Use a moisture barrier like taped aluminum foil or another reflective material. Make sure there’s a 10 mm (0.4 in) air gap between the moisture barrier and the clapboard. For the inside, a light wooden board with a thickness between 12–16 mm (0.5 – 0.65 in) is great for interior finishing. And don’t forget a 5 mm (0.2 in) air gap at the boundary of the ceiling panels and the top of the wall boards. A lower ceiling helps reduce the cubic size of the steam room, making it easier to heat. The normal height for a sauna is 2100–2300 mm (83-91 in), and the minimum height should be 2000 mm (75 in). Your ceiling insulation should be at least 100 mm (4 in) thick and well lined.

Ultimate Sauna Stones [Select & Maintain]

Take Advantage Of The Efficiency Of A Barrel Sauna!

Barrel saunas, with their unique design and cylindrical shape, are made of wood and are super efficient. They heat up faster than the traditional, cabin style saunas. The size of your barrel sauna matters, as a larger barrel sauna will take a bit longer to heat up than a smaller one. The thickness and type of wood used in the construction also play a role. Thicker wood takes a bit more time to heat up than thinner wood, but cedar is awesome for its insulation properties, helping to retain heat and reduce heat-up time. Our 1.75″ thick planks ensure your sauna heats up quickly and efficiently. The heater is crucial here, and a more efficient heater will do the job faster than a traditional wood-burning stove. The temperature desired also affects the heat-up time; a higher temperature means it’ll take a bit longer. These factors can vary, so it’s smart to consult a professional or check the manufacturer’s recommendations to get an estimate for your specific barrel sauna model.

Control Center Location and Surface Material Choices

The control center location and your surface materials are essential factors that impact your sauna experience. Whether you’re selecting the right size sauna heater or just tweaking your sauna setup, these elements matter.

Sauna or Steam? (Must-Know Health Facts!)

The Pros and Cons of Various Surface Materials

When it comes to surface materials, glass, stone, and tile each bring something special to the table. Glass looks great but might let heat escape more quickly. It’s easy to clean and maintain, though. Stone is a popular choice in Finnish saunas for its excellent heat-retaining properties and authentic touch. Tile is durable and water-resistant, making it awesome for steam rooms, but it might need a bit more heating power than other materials.

The Role of Insulation in Energy Efficiency

Insulation plays a big part in maximizing energy efficiency and helping you save on those electricity bills. Adding insulation foil during installation, as recommended by SaunaInter experts, can reduce your power requirements and improve thermal insulation in your sauna space.

Sauna Showdown: Dry Heat vs Steam [Which Wins?]

Finding the Perfect Spot for Your Control Center

Your control center needs to be accessible and safe from moisture and excessive heat exposure. You can go for wall-mounted controls outside the sauna room or built-in units inside. Each has its pros and cons, from easy access to additional wiring and installation costs.

Guidelines for Optimal Sauna Ventilation

A well-ventilated sauna enhances user comfort and helps maintain the longevity of your heating equipment. To get optimal ventilation, place fresh air vents above the sauna rocks and an exhaust vent near the floor on the opposite side from where fresh air enters. This setup ensures even heat distribution throughout the room. The total area of both intake and exhaust vents should be at least 1 square foot (0.09 m²) per 100 cubic feet (2.8 m³) of sauna space. With the right size heater and proper ventilation, you can enjoy your sauna without feeling suffocated or overheating too quickly. Remember to hire an experienced electrician for the installation to ensure a safe, enjoyable environment in your steamy sanctuary.

Exploring the Best Ways to Heat Your Sauna for Maximum Comfort


Choosing the right size sauna heater is crucial for a comfortable and efficient sauna experience. You need to consider many factors like room dimensions, location, power requirements, surface materials, ventilation, and safety measures. Making an informed decision that meets your needs is important. If you’re unsure about anything or have questions about sauna heating, The Sauna Heater can help. Our team of experts can guide you through the selection process and provide professional installation services for optimal performance and safety. Don’t miss out on your relaxation time because of the wrong heater size. Find the perfect fit for your home or commercial sauna.

FAQs in Relation to What Size Sauna Heater Do I Need

How Big Should My Sauna Heater Be?

The appropriate size for your sauna heater depends on your room’s dimensions and insulation. A general rule of thumb is 1 kW for every 45 cubic feet (1.27 m³) of space in a well-insulated sauna. For example, a 6’x8’x7′ room would likely need a 9kW heater.

Can a Sauna Heater Be Too Big?

Yes, a sauna heater can be too large for the space, leading to excessive energy consumption and overheating risks. It’s essential to choose a properly sized unit based on your specific needs and sauna room dimensions.

What Size Sauna Do I Need?

The ideal size of your sauna depends on personal preferences, available space, intended use, and the number of users. Generally, you should allocate two square feet per person for comfortable seating. Finlandia Saunas suggests planning for larger saunas if possible.

What Size Room Is a 9kW Sauna Heater Suitable For?

A 9kW electric or gas-fired infrared sauna heater is typically suitable for rooms with volumes between approximately 315-405 cubic feet (8.92-11.47 m³), depending on factors like insulation quality and desired temperature range.

Can you oversize a sauna heater?

Yes, an oversized sauna heater can heat the room too fast, underheat the rocks, body, and soul, leading to a löyly that feels like a wet diaper (wimpy and wet).

How do you calculate the heater for a sauna room?

To calculate the heater for your sauna room, measure the volume in cubic feet. Use 1 KW of power for every 50 cubic feet of space to reach the desired temperature. For instance, a 500 cubic feet room would need a 10 KW heater.

What size room is a 9kW sauna heater?

When considering two sauna heaters, a 6kW unit is for rooms 160-275 cubic feet, and a 9kW unit is for rooms 290-400 cubic feet.

What size breaker do I need for a 6kW sauna heater?

6kW heaters require a 30-amp breaker and 10/2 wire, unless they are positioned more than 30 feet from the breaker, in which case they will require an 8/2 wire. 9kW HUUM DROP heaters will require a 50-amp breaker and 8/3 wire.

Leave a Comment