Sauna Guide, Sauna Design, Sauna Heaters

How To Size a HUUM Sauna Heater Better Than The Calculator

How To Size a HUUM Sauna Heater Better Than The Calculator

Most people stop at step one, and undersize their HUUM Sauna Heaters. Say goodbye to guesswork and hello to peak performance, safety, and longevity.

Sizing your HUUM Sauna Heater is more than a step in setting up your sauna; it’s a crucial decision that impacts safety, performance, and the lifespan of your sauna. Follow along as we guide you through the professional approach to ensure you choose the right heater size for your space.

Hey there! We’ve seen a lot of confusion and mistakes sizing HUUM Sauna Heaters. We do this every day and wanted to share what works for us.

Getting it wrong can be dangerous, lead to failing heating elements, and will definitely not provide the optimal sauna experience.

Let’s Talk Kilowatts

The journey to the perfect sauna experience begins with sizing your heater correctly. And it all starts with your sauna room’s volume. But here’s the first mistake we see: some use the exterior dimensions of their sauna, not the interior. Big no-no. Let’s get those interior dimensions and jot them down. Got an irregular shaped sauna, like a barrel? You’ll need to do some extra math or let our AI tool, SaunaSizer, do the heavy lifting for you.

Insulation: The Size Changer

Now, onto the walls and roof. If they’re not boasting at least R-13 insulation, we’re multiplying your room’s volume by 1.5. Yup, you heard right.

This includes barrel saunas, log saunas, and any sauna kit with a single layer of wood. Seem like a lot?

Actually, HUUM’s official guidance will have you treat uninsulated walls the same as glass. We think that’s a little too extreme though.

For instance, this 392 cubic foot sauna will be adjusted by HUUM’s sauna calculator to over 1,500 cubic feet and say they have no heater for this small sauna.

Trust us, a large HUUM HIVE will heat a sauna much larger than that, even if it was made of glass!

Instead, we recommend multiplying the baseline volume of the sauna room by 1.5 if the walls are uninsulated or made of a single layer of wood.

Dealing with Glass

Speaking of glass, let’s not forget those windows and doors. Calculate the total area of glass in your sauna and adjust accordingly. HUUM has a nifty ‘glass adder’ recommendation that works great.

You need to add up the total area of the window surfaces and multiply by 4.8. Now you have your glass adder.

However, if you already multiplied the entire volume by 1.5 to compensate for uninsulated walls, then you need to use 3.2 as the glass multiplier instead of 4.8.

So to recap, we have calculated your rooms volume in cubic feet, multiplied by 1.5 if the walls are not insulated, and now we can add your ‘glass adder’ number to get our total adjusted cubic feet.

Crunching the Numbers

With our volume adjustments and glass adder sorted, it’s time to translate this into the heater size. HUUM’s rule of thumb is 1 KW per 35 cubic feet. But remember, other brands might suggest stretching that further. We reckon it’s because of HUUM’s extra rocks – they take a bit longer to heat up but offer that gentle, steamy embrace that keeps you coming back for more.

Still, we prefer to use 1 KW per 45 cubic feet, especially for larger saunas.

Selecting a HUUM Heater

Now that you have your adjusted volume, let’s see which HUUM sauna heater will work in your space.

Sizing a HUUM DROP

huum drop

The wall-mounted HUUM DROP is popular in small and medium sauna rooms. It comes in 4.5 KW, 6 KW, 7.5 KW, and 9 KW options.


Buy a HUUM DROP here.

Sizing a HUUM HIVE

The floor-standing HUUM HIVE and HUUM HIVE mini are the next most popular sauna heaters in North America from HUUM.

The extra rocks create a softer, more pleasant heat but beware they take longer to heat! Don’t undersize this heater!

HUUM HIVE mini sizing chart
HUUM Hive sizing chart in KW and volume

Buy a HUUM HIVE here.

HUUM HIVE MINI in an auroom vulcana modern glass sauna kit

Other options available in North America are the HUUM STEEL and HUUM CLIFF. These are perfect for smaller saunas.

The Final Touch

After all that number-crunching, it’s about rounding to the nearest suitable heater size, considering your local climate, build quality, and personal sauna-steaming preferences. And nobody does HUUM sauna heaters quite like Sauna Marketplace.

Eliminate the Guesswork

Want to cut straight to the chase and check your work? The SaunaSizer AI, available at, is your go-to. This chatbot is tailored for sizing HUUM Heaters, ensuring you pick the perfect match every time. Plus, if you grab your HUUM from us and use SaunaSizer’s wisdom in your order notes, we guarantee a performance that’ll make you swoon – or your money back.

See SaunaSizer for how to qualify.

Are these calculations perfect?

We think these are the best guidelines for sizing a HUUM sauna heater out there, but it’s still best to consult an expert at HUUM or Sauna Marketplace. SaunaSizer is getting better, but the sizing guidelines provided by all manufacturers tent to oversize very large saunas.

Indeed, there is still no substitute for experience.

Thank you for letting Sauna Marketplace guide your heat and steam journey. Got questions? Shoot us a message in the chat window. Here’s to making your sauna experience nothing short of spectacular!

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