SaunaSizer - What Size Sauna Heater Do I Need?

Sauna Heater Sizing with SaunaSizer AI™

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Sizing an Electric Sauna Heater

Manufacturers 'rule of thumb' guides for sizing electric sauna heaters range 1 KW for every 35 and 50 cubic meters of space. We started training SaunaSizer with 1 KW for every 45 cubic feet and it has made thousands of adjustments based on real life tests.

But there's much more to consider. Glass surfaces, stone walls, windows, and other uninsulated surfaces (including uninsuated walls) need to be factored in. SaunaSizer uses thermal resistance of materials, climate data of the location, and user experiences to personalize recommendations.

The square footage of uninsulated space should be given an effective value between 5% and 50% higher, depending on the surface.

The location also needs to be included if the sauna will be outdoors. Cold climates like Canada, Alaska, Minnesota, and Finland require an additional 25% added to the entire calculation. SaunaSizer determines this based on climate.

Sauna Marketplace Options

Let's see how SaunaSizer performs using saunas that we know best - the ones we sell on Sauna Marketplace.

What Heater Size For Auroom Cala? Exterior Width 59" (150cm) Exterior Depth 59" (150cm) Exterior Height 80.75" (205cm) insulated indoors

Based on the new dimensions you’ve provided, your sauna is approximately 218 cubic feet. Since it’s indoors and insulated, no adjustments are needed for materials or location.

For this volume, I would recommend a 5KW sauna heater.

NOTE: SPOT ON

What heater size for an Auroom Cala Glass Mini Sauna Kit 1-person, Aspen, DIY, Modular Cabin, Sauna Kit. Insulated. Exterior Width 37.4" (95cm) Exterior Depth 37.4" (95cm) Exterior Height 80.7" (205cm)

Great! Based on the dimensions you’ve provided, your sauna is approximately 53 cubic feet. Since it’s an indoor sauna and it’s insulated, we don’t need to make any adjustments for materials or location. Using our proprietary calculation, your sauna would benefit from a heater around 1KW. NOTE: We typically pair with a 2kw but largely due to the heater options available.

What heater size for a Auroom Baia Cabin Sauna Kit 2-person, Thermo-aspen, DIY, Modular Cabin, Sauna Kit. Insulated. Exterior Width 64.25" (163cm) Exterior Depth 64.25" (163cm) Exterior Height 80.75" (205cm)

Sure, let’s calculate the cubic feet of your Auroom Baia Cabin Sauna Kit first. The dimensions you provided are 64.25″ in width, 64.25″ in depth, and 80.75″ in height.

Since the sauna is insulated, we don’t need to adjust for materials.

As the sauna is a modular cabin, I’m assuming it’s indoors. Therefore, we don’t need to adjust for location either.

Let’s proceed to determine the heater size. Are you ready for the suggestions?

yes

Great! Based on the dimensions you provided, your sauna’s volume is approximately 200 cubic feet.

For a traditional Finnish sauna, you would need a heater power of approximately 5 KW.

NOTE: SPOT ON

What heater size for SaunaLife Model X6 Indoor Home Sauna XPERIENCE Series Indoor Sauna DIY Kit w/LED Light System, 2 to 3-Person, Spruce, 67" x 45" x 79". not insulated. full glass front wall.

Sure, let’s calculate the heater size for your SaunaLife Model X6 Indoor Home Sauna.

First, we need to calculate the cubic feet of your sauna. The dimensions you provided are 67″ x 45″ x 79″, which gives us a volume of 200 cubic feet.

Since your sauna is not insulated and has a full glass front wall, we need to adjust for these factors. For indoor saunas, we adjust the cubic feet upwards by 12% for the area of uninsulated walls and 21% for the area of the glass.

Assuming a standard sauna glass door is 24″ x 77″, the rest of the front wall is glass. The total front wall area is 67″ x 79″ = 5293 square inches. The glass area is 5293 – (24″ x 77″) = 3473 square inches.

The adjustment for the glass is 21% of 3473/144 = 51 cubic feet. The adjustment for the uninsulated walls (assuming all walls are uninsulated) is 12% of 200 = 24 cubic feet.

So, the total adjusted volume is 200 + 51 + 24 = 275 cubic feet.

Now, we can determine the heater size. For a traditional Finnish sauna, you will need 1 kW of heater power for every 43 cubic feet of sauna volume (after all adjustments).

So, your recommended heater size is 275/43 = 6.4 kW. We round this to the nearest size, so your recommended heater size is 6 kW.

Based on this, I would recommend the Harvia KIP 60 heater, which is a 6 kW heater. You can find it here: https://saunamarketplace.com/product/harvia-kip/

If your sauna is between 106 and 424 cubic feet and the ceiling is at least 71″, you might also consider a Saunum Air heater, which provides a more even sauna environment. Your sauna fits within this range, so you might find the Saunum Air – 5 suitable. You can find it here: https://saunamarketplace.com/product/saunum-air/

NOTE: SPOT ON

Sizing Sauna Heaters - Q&A

I'm considering the Harvia Virta 8kW heater for my basement sauna, measuring 5x8x7. Two walls border exterior cinder blocks, an 8' wall borders the furnace room, and the other 5' wall has the door opening to the living area. Despite planning for standard insulation, I anticipate heat loss from the interior walls. Would the Harvia Virta 8kW heater be too much for this setup?

Let’s calculate the volume of your sauna first. Your sauna measures 5 feet by 8 feet by 7 feet, which gives us a volume of 280 cubic feet.

Next, we need to adjust for the materials used in the construction of the sauna. You mentioned that two walls border exterior cinder blocks and one wall borders the furnace room. If these walls are uninsulated, we need to add 20% extra cubic feet for each of them. The 8′ wall that borders the furnace room and the 5′ wall that borders the living area would add 870.2 = 11.2 cubic feet and 570.2 = 7 cubic feet respectively.

So, the adjusted volume of your sauna is 280 + 11.2 + 7 = 298.2 cubic feet.

Since your sauna is located in a basement, we don’t need to adjust for the location as it’s not exposed to outside temperatures.

Now, let’s determine the heater size. For every 45 cubic feet of sauna volume, you will need 1 kW of heater power. So, 298.2 / 45 = 6.62 kW. We round this up to the nearest kW, which gives us 7 kW.

Based on these calculations, a 7 kW heater would be sufficient for your sauna. However, considering potential heat loss from the interior walls, an 8 kW heater like the Harvia Virta would provide a bit of extra power to ensure a comfortable sauna experience.

I'm looking to replace my old sauna heater, located in my garage, which is built with 1.75 inch thick solid timber walls and an insulated roof. The interior space is 4.8 m3, and there's one glass panel on the door. According to Sauna.ca's calculator, I need a 5.68 m3 sauna heater. I've assumed that a 6kw heater would be ideal, but I have two available options due to sales: a Sawo SCA-90NB 9kw heater and a Sawo SCA-45NB 4.5kw heater. Sawo's guidelines suggest a 4.5kw heater is suitable for up to 6 m3, but I'm worried it might be pushing its limits. However, the 9kw heater requires a 40amp circuit, while my existing circuit is 32amp. Should I go for the 9kw heater and potentially upgrade my circuit? The price difference between the two is about $100 USD. Any advice would be greatly appreciated.

Based on the information you provided, your sauna’s volume is 4.8 cubic meters. However, we need to adjust for the glass door and the uninsulated walls. A standard sauna glass door is 24″ x 77″, which is approximately 0.35 cubic meters. We add 50% extra for the glass, which is 0.175 cubic meters.

The total adjusted volume is 4.8 + 0.175 = 4.975 cubic meters.

Since your sauna is located in a garage, we don’t need to adjust for an outdoor location.

Now, we can determine the heater size. For a traditional Finnish sauna, you will need 1 kW of heater power for every 1.3 cubic meters of sauna volume. So, 4.975 cubic meters / 1.3 = 3.83 kW.

Rounding up, you would need a 4 kW heater. However, since you mentioned that your options are a 4.5 kW and a 9 kW heater, the 4.5 kW heater would be the closest fit for your sauna.

While the 9 kW heater would certainly heat your sauna, it would be overkill for your sauna’s size and would require you to upgrade your circuit, which would be an additional cost.

I'm having a sauna built, measuring about 6m3 or 214 ft3, located in Australia where winter temperatures typically exceed 10 degrees Celsius. The structure will feature heat-treated European Aspen internal walls and thermo-modified European Spruce exterior walls with earth wool insulation, along with a glass door. My builder suggests a 6kw Harvia heater, which fits the sauna's size according to Harvia specs. However, considering the glass door, I'm wondering if I should upgrade to the 8kw model, despite potential overkill. The price difference is minimal. What are your thoughts on choosing between the 6kw and 8kw heater?

First, let’s calculate the adjusted volume of your sauna. Your sauna’s base volume is 214 cubic feet. Since you have a glass door, we need to adjust for that. A standard sauna glass door is 24″ x 77″, which is about 11 cubic feet. We add 50% extra for the glass door, which is about 5.5 cubic feet. So, the adjusted volume of your sauna is 214 + 5.5 = 219.5 cubic feet.

Given that you’re in Australia where winter temperatures typically exceed 10 degrees Celsius, we don’t need to adjust for location.

Now, let’s determine the heater size. You will need 1 kW of heater power for every 45 cubic feet of sauna volume. So, 219.5 cubic feet / 45 = 4.88 kW. We round this up to the nearest kW, which is 5 kW.

Based on these calculations, a 5 kW heater would be sufficient for your sauna. However, since your builder recommends a 6 kW Harvia heater and the price difference to upgrade to an 8 kW model is minimal, it wouldn’t hurt to go for the 8 kW model. It would provide a faster heat-up time and could be beneficial if you like your sauna particularly hot or if you often have multiple people in the sauna at once.

I'm in the process of constructing an outdoor sauna with dimensions of 10ft x 12ft and an 8ft ceiling. I intend to insulate it thoroughly and I'm interested in the possibility of using a smaller KW electric heater than typically suggested for a space of this size. Could you provide recommendations on the appropriate size/KW for the heater?

Sure, let’s calculate the volume of your sauna first. The volume is calculated by multiplying the length, width, and height. So, for your sauna, it would be 10ft * 12ft * 8ft = 960 cubic feet.

Since you mentioned that you intend to insulate it thoroughly, we’ll only add a minimal 5% to the calculated volume. So, the adjusted volume is 960 * 1.05 = 1008 cubic feet.

Now, to determine the heater size, we generally need 1 kW of heater power for every 45 cubic feet of sauna volume. So, for your sauna, you would need 1008 / 45 = 22.4 kW. We always round up if we’re in between sizes, so you would need a 23 kW heater.

However, the largest heater we have on SaunaMarketplace.com is the Harvia Virta Pro, which goes up to 20 kW. For larger saunas, we often recommend using two heaters to reach the desired KW.

Here is the link to the Harvia Virta Pro: https://saunamarketplace.com/product/harvia-virta-pro/

As an expert, could you provide guidance on the general rule of thumb for choosing a sauna heater size? I'm considering a 4' x 4' Finnleo NorthStar Indoor Sauna, and the heater options are 1.7kw or 2.2kw. I've come across a heater size calculation based on the sauna's cubic footage. Could you clarify this for me?

Absolutely, I’d be happy to help clarify this for you.

First, we need to calculate the volume of your sauna. For a 4′ x 4′ sauna, we’ll assume a standard height of 7′. So, the volume of your sauna is 4′ x 4′ x 7′ = 112 cubic feet.

Next, we adjust for materials. If your sauna is made of standard materials with no large glass areas or uninsulated walls, we don’t need to make any adjustments.

Since your sauna is indoors, we don’t need to adjust for location either.

Now, we can determine the heater size. Generally, for a traditional Finnish sauna, you will need 1 kW of heater power for every 45 cubic feet of sauna volume. So, for your 112 cubic feet sauna, you would need a heater of approximately 2.5 kW.

Given your options of 1.7 kW or 2.2 kW, I would recommend going with the 2.2 kW heater to ensure your sauna heats up effectively. However, if you have the option to go slightly higher, a 2.5 kW heater would be ideal.

If you’re looking for a heater in that range, I would recommend the Harvia KIP 30, which is a 3 kW heater. You can find it here: https://saunamarketplace.com/products/harvia-kip/

I hope this helps! Let me know if you have any other questions.

Dear SaunaSizer, I'm planning on installing a compact sauna in my bathroom, specifically around 130-140 cubic feet. Considering electric harvia heaters, should I opt for a 4.5kw heater over a 3kw one, given the cubic foot range? Could you also provide insights on whether a heater that runs off a 20amp breaker would suffice without causing undersizing issues? Thank you!

Based on the volume of your sauna (130-140 cubic feet), a 3KW heater would typically be sufficient. However, considering that you’re planning to install the sauna in your bathroom, which might have more moisture and require more heat, opting for a 4.5KW heater could be a better choice.

As for the 20 amp breaker, it would be suitable for a heater up to 4KW if it’s a 240 volt circuit. If it’s a 120 volt circuit, it would only be suitable for a heater up to 2KW.

Given your situation, I would recommend the Harvia Vega Compact, which is available in 120 volts and would work well with your 20 amp breaker. You can find it here: https://saunamarketplace.com/products/harvia-vega-compact/

Please let me know if you have any other questions!

Dear SaunaSizer, I am designing a sauna in my walk-out basement with a size of approximately 280 cubic feet or 8 cubic meters. I initially planned on a 9 kW heater based on the 1 kW per cubic meter guideline. But I noticed that manufacturers state their 9 kW stoves can handle up to 14 cubic meters. How accurate is this? If I increase the room size to 384 cubic feet or about 11 cubic meters, would the heater be insufficient? I would appreciate your advice. Thanks!

Sure, I’d be happy to help you with that.

First, let’s calculate the heater size. For a traditional Finnish sauna, you will need 1 kW of heater power for every 45 cubic feet (or 1.3 cubic meters) of sauna volume.

For a sauna of 280 cubic feet, this would require a heater of approximately 6.2 kW (280/45), which we round up to 7 kW.

For a sauna of 384 cubic feet, this would require a heater of approximately 8.5 kW (384/45), which we round up to 9 kW.

So, for your initial plan of a 280 cubic feet sauna, a 7 kW heater would be sufficient. If you decide to increase the room size to 384 cubic feet, a 9 kW heater would be appropriate.

As for the manufacturers’ claims, they often provide a range that their heaters can handle. However, it’s always best to calculate the exact size needed for your specific sauna to ensure optimal performance.

Now, let’s find the best heater for your sauna. I’ll need to know a bit more about your sauna’s construction and location to make the best recommendation. Could you please tell me what materials are used in the construction of your sauna and where it is located?

I am considering buying an outdoor barrel sauna, specifically the Dundalk Serenity, with an approximate interior space of 175 cubic ft. For the sake of convenience, we are interested in a wifi-controlled heater such as the Huum Drop, available in 6 or 9kw models. Considering our location in a region with harsh winters (we're expecting 0 degrees Fahrenheit tomorrow), would opting for the 9kw model be excessive for our sauna's size or advisable for maintaining warmth during cold days? Also, would a larger heater potentially heat up too swiftly in summer, affecting the heat of the stones and the quality of the löyly? I would greatly appreciate your advice. Thank you!

To determine the appropriate heater size for your sauna, we need to consider the volume of the sauna, the materials used in its construction, and the location of the sauna.

Given that your sauna is a barrel sauna, we’ll assume it’s made out of uninsulated 1.75″ spruce and there’s one glass door and no windows unless otherwise noted.

The volume of your sauna is 175 cubic feet. Since it’s a barrel sauna, we need to adjust the cubic feet upwards by 18% for the area of uninsulated walls. This gives us an adjusted volume of approximately 206 cubic feet.

Considering your location with harsh winters, we should add 25% to the calculated volume. This gives us a final adjusted volume of approximately 258 cubic feet.

For a traditional Finnish sauna, you will need 1 kW of heater power for every 39 cubic feet of sauna volume (after all adjustments). This means you would need a heater of approximately 6.6 kW.

Given your specific circumstances, I would recommend the 9 kW Huum Drop heater. This will ensure your sauna heats up quickly and maintains its heat during the cold winter months.

In terms of your concern about the heater heating up too swiftly in the summer, a larger heater will indeed heat up the sauna more quickly. However, the quality of the löyly (the steam produced when water is thrown on the hot stones) is more dependent on the humidity and temperature within the sauna, which can be controlled by adjusting the amount of water thrown onto the stones.

Here is the link to the Huum Drop 9KW: https://saunamarketplace.com/products/huum-drop/

I hope this helps! If you have any other questions, feel free to ask.

Hello, I'm currently designing my sauna and I'm trying to understand how the size and volume of the sauna relate to the capacity of the heater. The power supply I have access to won't accommodate a heater greater than 7Kw. The volume of my initial design is 10.3m3, which I attempted to reduce to about 8m3 by shortening the sauna's length by 60cm. Can I use solid benches to decrease the volume of the room further, possibly bringing my original, full-length design down to around 8m3? Although I haven't seen this method used often, I'm curious if there are reasons against it. Also, judging the room's size from blueprints is challenging, and I worry the smaller design may be too tiny. Can anyone with a sauna of similar size share their experiences? Thank you!

Thank you for the detailed information. To determine the appropriate heater size, we need to calculate the total volume of the sauna room and adjust for materials used in the construction.

From your description, your sauna’s volume is 10.3 cubic meters. However, you’re considering reducing it to 8 cubic meters by shortening the length and possibly using solid benches.

While using solid benches can technically reduce the volume of the sauna, it’s not a common practice and it’s not typically factored into the calculation for heater size. The heater needs to be able to heat the entire space, regardless of whether it’s occupied by benches or not.

Given your power supply limitation of 7KW, let’s calculate the maximum volume your sauna could be. Generally, for a traditional Finnish sauna, you will need 1 kW of heater power for every 1.3 cubic meters of sauna volume. So, a 7KW heater can effectively heat a sauna of approximately 9.1 cubic meters.

If you’re able to reduce your sauna’s volume to 8 cubic meters, a 7KW heater should be sufficient. However, if you keep the original volume of 10.3 cubic meters, the 7KW heater may not be able to heat the sauna effectively.

As for the size of the sauna, it’s a personal preference and depends on how you plan to use it. A smaller sauna will heat up faster, but it will also have less space for you to move around.

I hope this helps! If you have any other questions, feel free to ask.

I'm planning a sauna build with a limited power supply for a 7KW oven. My initial design has a volume of 10.3 m³, but I'm considering reducing it by 60cm to approximately 8 m³. Can I use solid benches to shrink the room volume, and if so, will it impact the feel of the room? Also, can anyone with a similar-sized sauna share their experience?

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What size of heater would be needed for a custom-built, outdoor, insulated red cedar sauna with dimensions of 7’ by 5’ by 7’, assuming it will be used 3-5 times a week, located in Idaho?

Based on the information you provided, your sauna’s volume is 245 cubic feet. Given that it’s an outdoor sauna in Idaho, we’ll add an additional 16% to the calculated volume, bringing it to approximately 284 cubic feet.

Therefore, I would recommend a 7KW heater for your sauna.

For a 7KW heater, I suggest the Harvia KIP 70: https://saunamarketplace.com/product/harvia-kip/

Also, since your sauna is within the range of 106 to 424 cubic feet, you might want to consider a Saunum Air circulating heater. It can provide a more even sauna environment for your layout. Here is the link to the Saunum Air: https://saunamarketplace.com/product/saunum-air/

Please let me know if you need more information or have any other questions!

I have made my decision to purchase the Almost Heaven Allegheny outdoor sauna, however, I'm contemplating whether I should upgrade to the 10.5kw Virta. My goal is to have a quicker heating period, but I'm unsure if the improvement would be minor. The interior dimensions of the sauna room are 75"W x 75"D x 84"H. I would be grateful for any advice you can provide in advance. Canada.

Thank you for sharing your location. Given that Canada has a colder climate, we’ll adjust the volume of your sauna by 24%. This brings the total volume to approximately 487 cubic feet.

Based on this adjusted volume, a 10.5 KW heater would be a suitable choice for your sauna. It will provide a quicker heating period compared to a smaller KW heater.

I've recently placed an order for a Madison Sauna, manufactured by Almost Heaven, via Salus Saunas. I've chosen to upgrade the heater from the standard 4.5KW to a 6KW Harvia Kip Heater. The sauna's dimensions are 65" x 53" x 78". I've also consulted Almost Heaven directly, and they recommended further upgrading to an 8KW Harvia Kip heater. But when I relayed this to Salus, they suggested that 6KW is an ideal fit for this sauna and that 8KW might be excessive, even potentially scorching the roof. I'm caught in the middle of conflicting advice from two sources who both seem to be knowledgeable. Given that the unit hasn't been shipped yet, I can still make changes. I'd greatly appreciate any insights or recommendations you may have! Not insulated. Indoors

Based on the dimensions you’ve provided, your sauna’s volume is approximately 180 cubic feet. Considering the material and location of your sauna, a 6KW heater would be a suitable choice for your sauna.

I would recommend the Harvia KIP 6KW heater, which is a reliable and efficient option. You can find it here: Harvia KIP 6KW

However, if you’re interested in a more even sauna environment, your sauna would also benefit from a Saunum air circulating heater, specifically the Saunum Air – 5, given your sauna’s cubic feet and ceiling height. You can find more information about it here: Saunum Air – 5

Please let me know if you need further assistance!