What Does It Actually Cost to Run a Hot Tub?
People ask me about the price of the tub. Almost nobody asks about the second number, which is the one that actually decides whether they end up happy with it: what it costs to keep running once it is sitting in the yard.
I get why. The sticker price is on the page and the running cost is not. So here it is, plainly, with the arithmetic shown so you can swap in your own numbers.
The short answer
A conventional electric hot tub costs somewhere around $30 to $60 a month to run in a mild climate, and more than that through a cold winter. The important part is not the size of that number. It is that you pay it every month whether anyone gets in the tub or not.
Where that number comes from
An electric spa does two things constantly. It holds several hundred gallons of water at temperature, and it runs a pump to keep that water moving and filtered.
Most residential spas have a heater somewhere around 5.5 kilowatts. On a mild day, with a decent cover, that heater might run a couple of hours in total across twenty-four hours just replacing heat that has escaped. At the US average of about 17 cents per kilowatt-hour:
5.5 kW Ć 2 hours = 11 kWh a day
11 kWh Ć $0.17 = about $1.87 a day
Roughly $56 a month, before the pump
Change any of those assumptions and the answer moves a lot. A well-insulated tub with a tight cover in Florida might sit near the bottom of the range. The same tub uncovered in a Midwest February will run the heater far more than two hours a day and the bill climbs accordingly. Your own electricity rate matters more than anything else in that sum, so look it up on your bill rather than trusting my average.
The part that catches people out
Nobody minds paying for something they are using. What surprises people is the bill in the months they are not.
If you own a short-term rental, this is worth sitting with. A hot tub that costs you $45 a month runs to about $540 a year ā and a good chunk of that is spent in the weeks the property is empty, holding water at 102 degrees for nobody. You cannot switch it off between guests either, because a spa takes many hours to come back up to temperature and nobody wants to arrive to a cold tub.
So the honest way to look at an electric spa is that it is a fixed monthly cost attached to the property, not a per-use one.
How a wood-fired tub changes the math
A wood-fired hot tub is a different animal. There is no heater holding the water, no pump, and no standing draw. It costs nothing at all until somebody lights it.
When you do light it, you are burning firewood. A 422-gallon tub takes roughly two to three hours to come up from cold and gets through something in the region of an armload to a wheelbarrow of seasoned wood, depending on how cold it is outside. If you buy firewood at around $250 a cord, that works out to roughly $3 to $6 a soak. If you cut your own, it is free.
Put those side by side over a year, assuming a couple of soaks a week:
| Ā | Electric spa | Wood-fired tub |
|---|---|---|
| Used twice a week | ~$540 a year | ~$420 a year in wood |
| Used twice a month | Still ~$540 a year | ~$100 a year in wood |
| Not used for three months | You still pay | You pay nothing |
| Power cut | Stops working | Works fine |
Used heavily, the two are closer than people expect. Used occasionally, or seasonally, or on a property that sits empty part of the year, the wood-fired tub wins by a wide margin.
The costs nobody puts in the brochure
Two more things belong in this comparison, and they usually get left out.
Installation. An electric spa needs a dedicated circuit run by a licensed electrician, and often a permit. Depending on how far your panel is from where the tub is going, that can be a four-figure job on its own. A wood-fired tub needs a level pad and a garden hose. That is the whole installation.
Chemicals. A spa holds the same water for months, so it needs testing and dosing to stay safe. A wood-fired tub is generally drained and refilled instead, which costs water rather than chemicals and takes the guesswork out.
Where a wood-fired tub is genuinely worse
I would rather tell you this now than have you find out in January.
You have to plan ahead. Two to three hours from cold means it is not something you turn on from your phone on the way home. If guests are using it, that is one line in the house manual: light it before dinner, not after.
There are no jets. If what you actually want is a bubbling massage spa, a wood-fired tub is not that. It is a hot soak with a fire attached to it, and people either love that or find it underwhelming.
Somebody has to tend the fire. Not much ā but it is not nothing, and it is not automatic.
So which one
If the tub will be used most days by people who want jets and instant heat, and running a new circuit is straightforward, an electric spa makes sense and the monthly bill is the price of that convenience.
If it will be used in bursts, if the property sits empty part of the year, if getting power to the spot is awkward or expensive, or if the fire is honestly half the appeal ā a wood-fired tub will cost you less to own and almost nothing to leave alone.
For a rental, there is one more thing worth weighing that has nothing to do with cost. Steam coming off a cedar tub with snow on the ground is the strongest winter photograph a property can have, and hardly any listing in the country has one.
If you want to talk it through against your actual space and your actual electricity rate, get in touch ā I would rather point you at the right one than the expensive one. You can see the range on the wood-fired hot tubs page.
The figures here are estimates based on a 5.5 kW heater, the US average electricity rate of about 17 cents per kilowatt-hour, and firewood at around $250 a cord. Your own numbers will differ ā use the method rather than my totals.