Cold plunge electricity cost: the formula and real examples

If you're wondering how much electricity a cold plunge uses, the short answer is that the chiller is almost the whole story, and its running cost is usually a few dollars to a few tens of dollars a month. The exact figure depends on three things you can look up or estimate: the chiller's listed wattage, how many hours it actually runs each day, and what your utility charges per kilowatt-hour. This page gives you the formula, the wattage numbers I could verify, and worked examples that are clearly my own arithmetic, so you can swap in your own rate and see your real cold plunge electricity cost.

The angle of this page: a formula, not a guess

Most pages on this topic hand you one number ("about $X a month") and no way to check it. I'd rather give you the formula and the line items, then be honest about the one input nobody can know for you: how long your chiller runs. I don't test products, so nothing below is a measurement from a tub in my yard. Wattages come from listings and spec sheets, the price per kWh comes from the U.S. Energy Information Administration, and every total is arithmetic I did and show.

The formula for cold plunge electricity cost

Here it is, in three steps.

1. Daily energy in kWh = chiller watts × hours running per day ÷ 1,000
2. Monthly energy in kWh = daily kWh × 30
3. Monthly cost = monthly kWh × your price per kWh

That's the entire model. A "cold plunge kwh" figure is just watts, time and a unit conversion. The hard input is hours running, which is not the same as hours the unit is plugged in. A compressor chiller cycles on and off to hold a set temperature, so a unit that's powered all day might only draw full power for a fraction of it. I'll call that fraction the duty cycle, and I'll use plain hours per day in the examples so there's nothing hidden.

What chillers list for power draw

Cold plunge chiller power consumption varies less than you might expect across the common half-horsepower class. These are the figures I could find on pages I opened.

A few notes on that table. The newsletter in doesn't name a brand for its 1/2 HP and 1 HP figures, and I couldn't tell who wrote it, so treat those two rows as a rough guide rather than a spec sheet. The Hydrofarm page gives amps but no watts, and amps times volts only gives an upper-end idea of the draw (5.0 × 120 = 600 VA, my arithmetic), not a measured number. And one more thing: the Plunge Pro Chiller Gen 2 page lists "1 kW" for wattage, but that figure is attached to the heater, and it calls for a dedicated 15A circuit on 120V. I couldn't find a listed cooling-only wattage there, so I've left that unit out of the cost examples rather than guess.

The takeaway is simple. Within the half-horsepower class, the listed difference is about 60 watts. That's small enough that your electricity rate and your run time will matter far more than which of those brands you pick.

Your price per kWh (and why it varies so much)

For the rate, I use the EIA. It reports that the annual average residential retail price in 2025 was 17.30 cents per kWh. That's a national average, and your bill can be well off it. The same EIA page says the annual average retail price for all customer types ranged from 35.72 cents per kWh in Hawaii to 8.20 cents in North Dakota in 2025. Note the wording: that range covers all customer types together, not only households, so your home rate will differ somewhat from either end.

Check your own utility bill for the per-kWh charge. Some bills split it into supply and delivery, and some use time-of-use pricing, where the same kWh costs more in the late afternoon than overnight. I haven't verified how any particular utility prices this, so look at yours.

Worked examples: monthly cost at the national average

These are my arithmetic, using 17.30 cents per kWh, a 30-day month, and a 500 W chiller (the PlungeBox figure). The only variable is hours running per day.

Take the 4-hour row as the worked line: 500 W × 4 h ÷ 1,000 = 2.0 kWh a day. Times 30 gives 60 kWh. Times $0.173 gives $10.38. Over a year of 365 days, the same assumption is 730 kWh and about $126.29 (my arithmetic).

I can't tell you which row is yours. A well-insulated tub in a mild garage might sit near the top of that table. A thinly insulated tub on a hot patio probably runs far more. I'm only describing the direction here, not putting a number on it, because I haven't seen a source that quantifies it. The same newsletter that lists the wattages says insulation quality affects chiller performance and that hotter climates such as Florida or Arizona need more powerful chillers.

Cold plunge monthly cost by chiller size

Now hold the usage steady and change the chiller. Same assumptions: 4 hours running per day, 30 days, 17.30 cents per kWh, all my arithmetic.

Two lessons come out of that. The three half-horsepower units land within about $1.25 of each other, so don't pay a premium chasing a few watts. And a 1 HP unit costs roughly double to run for the same hours, but it may also cool a bigger tub faster and finish its job sooner, which means "same hours" isn't a fair assumption. If you buy a bigger chiller than your tub needs, I'd expect it to cycle less, not more, but I can't prove that from the sources I opened.

How your rate changes the answer

Keep the 500 W chiller and the 4-hour day (60 kWh a month) and vary only the price. This uses the all-customer-type rates from, so treat the ends as rough bookends, my arithmetic:

Same tub, same habits, and the bill is about four times higher at one end than the other. This is why a headline "cold plunge monthly cost" from a blog in another state may not fit you at all.

Sanity-checking a manufacturer's own cost claim

The PlungeBox page lists an "estimated daily electricity cost" of $0.49 to $0.63. I couldn't find the rate or hours behind that estimate on the page. Working backward with my own assumptions: at 17.30 cents per kWh, $0.49 to $0.63 is about 2.8 to 3.6 kWh a day, which would be roughly 5.7 to 7.3 hours of running at 500 W (my arithmetic). That's a plausible range, and it tells you the maker's figure is not a low-ball one-hour number. It also shows why you should always ask for the hours behind any quoted running cost.

What I left out of the numbers

The totals above cover the chiller. A real setup has other draws that I haven't priced because I couldn't verify their wattage from the pages I opened: a circulation pump, ozone or UV sanitation, a filter, and the controller. Some units also include a heater. The Plunge Pro Chiller page lists a 1 kW heater figure, so if you use a heating feature, add its energy separately. At 1 kW, one hour of heating is 1 kWh, or about 17 cents at the national average (my arithmetic).

Also not in the numbers: the purchase price, filter replacements, water and sanitizer. Those can outweigh the power bill. The spec pages I opened list chillers from $1,099.99 to $1,386.11 to $1,799.00 and $3,490 for a different class of product, so at about $10 a month in electricity, the chiller price dominates the first few years of ownership.

Mistakes I'd watch for

• Using plugged-in hours instead of running hours. The chiller isn't pulling full power around the clock.
• Copying someone else's dollar figure without their kWh rate.
• Forgetting that a lid and insulation change how often the compressor has to run.
• Assuming a bigger unit always costs more per month. It draws more while running, and the hours may differ.
• Ignoring the circuit. The Plunge page calls for a dedicated 15A circuit at 120V, and the Hydrofarm listing specifies a GFCI-protected cord. Ask an electrician about your own panel and outlet.

Frequently asked questions

How much electricity does a cold plunge use per day?

It depends on the chiller's wattage and run time. Using a 500 W chiller running 4 hours a day, my arithmetic gives 2.0 kWh. Run it 8 hours and it doubles to 4.0 kWh.

What is a typical cold plunge monthly cost?

At the 17.30 cent national residential average, my examples range from about $5 to about $31 a month for a 500 W chiller running 2 to 12 hours a day. A 4-hour day lands near $10. Your utility's rate and your tub's insulation can move that a lot.

Does a cold plunge without a chiller use any electricity?

A plain tub filled with water and ice uses none for cooling, though you may still run a pump or filter if it has one. The tradeoff is ongoing ice and effort. I haven't found a source I trust for ice costs, so I won't put a number on it.

Is a 1 HP chiller much more expensive to run than a 1/2 HP chiller?

On the listed figures, 1,100 W versus 510 W, it draws about twice as much while running. At 4 hours a day and 17.30 cents, that's $22.84 versus $10.59 a month (my arithmetic). A larger tub or a hot climate may justify it, but check your tub's volume first.

Do ambient temperature and sunlight change the cost?

Yes, in direction if not in a figure I can verify. A warmer location means the chiller has more heat to remove, so it runs longer. I can't quantify the difference from the sources I read.

What I would do

Before you buy, write down your utility's price per kWh and decide on a realistic run time. I'd budget for 4 to 8 hours a day if the tub is outside, then use the formula: that's roughly $10 to $21 a month at the national average with a 500 W unit (my arithmetic). For a normal home tub, I'd pick a half-horsepower chiller from a seller that publishes its wattage, put the tub in shade with a tight lid, and ignore the 60-watt differences between brands. Put your money into insulation and a lid before a bigger compressor. And if you have heart conditions, blood pressure issues or are pregnant, talk to your doctor before you start cold exposure at all, because that matters more than the power bill.

To see what the chiller itself costs to buy, read cold plunge cost. If you are not sure you need one at all, start with do you need a chiller.