How to Calculate Total Wattage of Baseboard Heaters
Brad Pretty, 2 years ago   |    31   |    1 min read   |    54042

Many homeowners wonder how they can calculate the current total wattage of their baseboard heaters in each room. If you’re thinking about purchasing Mysa Smart Thermostats for your home, you should know there’s a limit: Mysa can handle up to 3,800W. This is around the standard for any high voltage thermostat. We strongly recommend you do not exceed this wattage.

But now you’re asking:

“By golly, how do I know if I’m over the limit?”

Well, there’s a couple of ways to check:

Method One

The easiest and simplest way to calculate the total wattage of your current baseboard heaters is to locate the manufacturer’s label on your heaters. The wattage is often listed on a sticker. If the wattage is not listed on the label, you can determine the wattage of each heater with this simple formula:

If you get the information directly from a sticker on the heater, it should be an exact figure and not an estimate.

Method Two

If you are unable to read or locate the manufacturer’s label, then you can estimate the wattage for each baseboard by measuring the length. As a general rule, you can approximate the heater’s wattage by using the following calculation:

However, remember that this is an estimate. If your calculations come anywhere close to the 3,800W limit, please consult a professional to make sure that Mysa is compatible.

Multiple Heaters

Remember that your total wattage must include every heater attached to a single thermostat. To calculate this, simply calculate the wattage of each heater and add them all together.

If you’re anywhere under 3,800W it’s about time you Meet Mysa!


  1. mitch

    Very nice! Thanks.

  2. Charles Durning Carroll

    So if one has a large home with baseboard electric heaters what is one to do? I have 5 Aube thermostats controlling 4 large StelPro (~6ft) baseboard heaters. (The fifth one is in a walk in closet and can be left as it is.)

    1. Rebecca Collins

      Hi Charles,

      You could simply get one Mysa per baseboard heater. We currently have a discount for bundles of 3 or 5 units. I hope that helps!

  3. Bryan Hannegan

    I have four baseboard electric heaters with a total rating of 4,190W in a single room controlled by an existing King single-pole thermostat. If I am reading you correctly, I would not be able to replace that thermostat with a Mysa? One of the four heaters is a small 420W unit that I could uninstall to bring under your 3,800W limit, I suppose.

    1. Brad Pretty

      That is correct, Bryan.

  4. Leigh Vandewalker

    Will mysa work as an ordinary thermostat without WiFi? I’m updating a cottage that I haven’t yet put internet at- the options for that are actually limited, so I need to put some thought into which type to choose.

    1. Brad Pretty

      Yes, but just a standard up and down thermostat. In order to use smart features and scheduling you will need WiFi.

  5. Rebecca Huggins

    My electrician says I need 30amps for my two long baseboard heaters that are currently on their OG 1968 Art Deco thermostat! Do you have a smart thermostat compatible with that?

    1. Brad Pretty

      Unfortunately Mysa maxes out at 16 amps. We don’t have a product that supports such an amperage.

  6. Brad Kendall

    Would like to install on a 240V circuit with 2 baseboard heaters. Each is 8.3A, so 1992W each= 3984W total. Yes…JUST over the 3800w max recommendation. Being so close, could I get away with your system on this? I am hoping the recommendation is at least a little conservative. Looking forward to your response.

    1. Brad Pretty

      We are certified for 3800W, so we do not recommend going over that.

  7. Myrian Grondin

    What happens if it’s a bit higher, like 4000w. Will it works? Will it restart by itself? Will it stay Closed?


    1. Brad Pretty

      It is incompatible with 4000W, which means that it an electric hazard to hook up at all.

  8. Linda

    I have radient heat in my ceilings. I also have small baseboards in areas like the hall & bathrooms. I have thermostats in every room,so I’m guessing that there is no radient heat through the ceilings in the hall & bathrooms or I wouldn’t have the baseboards. The thermostats are 240v high voltage system. Am I compatable for a mysa? Also,during a natural power outage or power surge due to weather,will the thermostat reset to a different degree if I’m not home,does it have memory or what will it do? Thank you for your help.

    1. Brad Pretty

      Mysa could possibly be compatible with the above system if the system meets the required specifications, which you can find on

      The number of wires, amperage, and wattage are all very important when it comes to radiant heat.

      After a power outage, when the Mysa comes back on it will return to the last temperature it was set to.

      1. Mark Johnstone

        Hi Mysa…after a power outage, will it lose the program if you have different heat settings for different days? I understand it will go back to the last temp it was set to….but does it lose the entire program?

        1. Brad Pretty

          As long as it reconnects to the internet it will return to its normal schedule. We’ve made great strides in ensuring that happens with most setups!

  9. Christian

    Hi! My new Mysa has been connected for 7 hours now, and the room is cold, baseboards barely heating (set to 23 but stays at 19), all within specs ( 3 BB for 3000w total) and wifi working great… what is the possible issue? Its make or break at this point!

    1. Brad Pretty

      Hey Christian,

      Sorry you’re having issues. It would be best to contact our support team at to help you further.

  10. Jayme

    I have one room with electric baseboard and an electric forced fan. Do I need to add the wattage of both units to confirm it is under 3800 W? How do I check wattage on the forced fan?

    1. Brad Pretty

      Hey Jayme,

      if they are wired to the same thermostat, yes you would. There should be a sticker on the fan-forced heater somewhere denoting what Wattage it is rated for.

      1. Jayme

        Thanks Brad. When I go through the compatibility test, select multiple heat sources – electric baseboard / electric fan – forced and check all the parameters I get this response:
        “Mysa will work to replace your baseboard or fan-forced heater thermostats. Unfortunately, it will not replace the other thermostats.”
        Can you confirm it will work for my baseboard AND fan forced heater thermostats? It could read that it only works for single types – like thermostats for just baseboard or just forced fan. Thanks!

        1. Brad Pretty

          Hey Jayme,

          It should work, but this use case is a little on the rare side. I encourage you to get in touch with our very knowledgeable support team who should be able to confirm this for you:

  11. Ash

    I have two 8 feet electric baseboard heating, looks like 3840 watt (16×240), will Mysa work?

    1. Brad Pretty

      Looks like you’re slightly over the limit. Please contact our support team at to see if there’s an option for you.

  12. Matt

    Hello, I have 2 8 ft Baseboard heaters connected together, 3600 W but how do I know how many Amps?

    1. Brad Pretty

      The Amps should be listed on the sticker as well. If not, you can google the model number! If it’s a standard baseboard heater it is unlikely that it will surpass our limits.

  13. Chip Harnett

    Hello. I have 5 rooms with baseboard heat and each room has its own analog thermostat, but they all go to the same breaker. I was going to install 5 of these mysa units to replace the old king units. 6 wires in the box. Will this work?

    1. Alexander Chafe

      Hey, Chip! Please reach out to our support team at and they would be happy to help you to assess your home’s compatibility with Mysa 🙂

  14. Bill Johnsen

    The specs of the thermostat is 3800 Watts @ 240VAC, what would be the specs of the thermostat (& load capacity) when the line voltage is 208VAC?

    1. Alexander Chafe

      Hey, Bill. There’s also a 3,800-watt total capacity limitation for 208VAC systems. However, we do suggest completing our online compatability checker to ensure that Mysa is compatible with your heating system, as we’re not compatible with all 208VAC systems:

Leave a Reply

Related Posts