Hot tub running costs usually get quoted as a single range, with nothing behind it.
Electricity, the biggest part, doesn't have to be a guess. Every spa model certified for sale in California is listed with its standby wattage, measured to the same industry test, and the arithmetic from there is short. The rest of the bill is harder to pin down, and I'll say where.
Key takeaways
- Electricity is the cost you can calculate: standby watts × 8,760 hours × your rate. California's spa label uses the same arithmetic.
- Certified standby for Hot Spring, Jacuzzi, Sundance and Bullfrog tubs runs from 120 to 295 watts, mostly by size.
- The label figure is for comparing tubs. Soaking, heating fresh fills and a cold yard all add to it.
- 120 and 240 volts cost about the same to keep hot. Bullfrog's A6 is certified at 166 watts either way.
- The cover is the biggest thing you control. The CEC says foam that has absorbed water loses nearly all its insulating value.
Electricity: work it out from the standby watts
The California Energy Commission's appliance database lists more than 2,000 portable spa models, each with a standby wattage: the average power it draws to hold its temperature and filter its water, measured with the cover on under the ANSI/APSP/ICC-14 test. California's required spa label turns that into a yearly figure with the same arithmetic you can do yourself:
- Watts × 8,760 hours ÷ 1,000 = kWh a year
- kWh × your rate = cost a year
Here's what that gives for some of the models listed now, at the US average residential rate for 2026 so far, 18.19 cents a kWh.
| Fill (gallons) | Standby watts | A year | A month | |
|---|---|---|---|---|
| Sundance Tacoma | 145 | 120 | $191 | $16 |
| Jacuzzi J315 | 210 | 136 | $217 | $18 |
| Hot Spring Jetsetter (115 V) | 220 | 144 | $229 | $19 |
| Bullfrog X6R | 290 | 166 | $265 | $22 |
| Hot Spring Sovereign | 300 | 169 | $269 | $22 |
| Sundance Cambria | 335 | 207 | $330 | $27 |
| Jacuzzi J385 | 455 | 217 | $346 | $29 |
| Hot Spring Envoy | 435 | 225 | $359 | $30 |
| Bullfrog M9 | 588 | 295 | $470 | $39 |
When the DOE averaged the database in 2021, a standard spa came to 194 watts: 1,699 kWh a year, about $309 at the national rate.
Your rate matters as much as your tub. The EIA's state averages for 2026 so far run from 12.90 cents in Nebraska to 46.28 in Hawaii. The same 194-watt tub costs about $219 a year in one and $786 in the other. Your bill shows your own rate.
What the standby figure leaves out
California's label says plainly that the data "should be used only for comparison of spa models." It is a lab test, with the cover on and nobody in the tub. Three things push a real bill above it.
Using the tub. The CEC estimates that standby is about 75 percent of the energy a spa uses over its life. The rest is heating fresh fills and running the jets. If yours matches that, the total is about a third more than the standby figure: around $412 a year for the 194-watt average.
Your climate. Heat loss rises with the difference between the water and the air. A tub at 102°F in 30°F air has a 72-degree difference to fight, against 32 degrees in 70°F air, so it loses heat roughly twice as fast. A cold yard costs more than the label, and a warm one can cost less. The winter guide has what the makers say about running a tub through the cold.
The cover's condition. The test uses the cover the maker specifies, not one that has spent years taking on water. More on that below.
The DOE's record has a second estimate that points the other way. Industry, utility and efficiency groups worked from the federal household energy survey and put the average at 1,567 kWh a year per household, a little under the DOE's standby-only 1,699. Treat the standby figure as the right scale for your tub, not a forecast of your bill.
The cover is the lever
The CEC's staff report calls the insulation and the cover the greatest opportunity to save energy in a spa, and the cover is the part you control after you buy.
Most covers use expanded polystyrene foam, and the CEC notes that it can absorb a significant amount of water, and that foam which absorbs water loses nearly all its insulating value. A waterlogged cover is heavy and does next to nothing.
Two more points from the CEC, worth knowing when you replace one:
- The hinge. The usual cover folds along an uninsulated strip about two inches wide that runs its full length, and the CEC says that allows significant heat loss. A single-hinge or insulated-hinge design reduces it.
- A floating blanket, a sheet that sits on the water under the cover, is another barrier against heat loss and evaporation, and keeps moisture and chemicals off the cover's underside.
Keeping the cover itself in good shape is in the maintenance schedule: clean it monthly, no soap underneath, and open it after a shock.
Go deeperWhy evaporation costs so much heatThe same physics, on a pool. Stopping evaporation matters more than collecting sun.Should you turn it down between uses?
This gets argued about constantly, and it has an actual answer: turning it down always saves some energy, and over a short spell, not much.
Turning it down always reduces the loss rate, because loss scales with temperature difference. Here's the math for a 400 gallon tub drawing the DOE's average 194 watts, which is about 4.7 kWh a day:
Reheating 10°F takes about 400 gallons × 8.34 lb × 10 BTU, which is roughly 10 kWh, about $1.78 at the national rate.
Dropping 10°F in 50°F air cuts the temperature difference by about a fifth, so it saves just under 1 kWh a day, about $0.16.
Set side by side, those look like a ten-day break-even. They aren't one. The 10 kWh of reheat only puts back heat the tub lost while it cooled, and it lost that heat more slowly than it would have at full temperature. With an electric heater, the total always comes out lower when you turn it down. Bullfrog's manual says the same: lowering the temperature cuts the cost of running the tub.
Between ordinary evening soaks, the saving is real but tiny, and the tub won't be ready when you want it. On a time-of-use tariff, when you reheat matters too.
120 or 240 volts
The heater is the difference. Jacuzzi's J-300 heater is 4 kW on 240 volts and 1 kW on 120, and Hot Spring's Highlife heater is 6,000 watts and 1,500.
People assume the bigger heater costs more to run. The certified figures say it doesn't. Holding a temperature takes as much energy as escapes, whatever size the heater is, and California's database lists several tubs certified both ways:
- Bullfrog A6: 166 watts on 240 volts, 166 on 120
- Bullfrog X6R: 166 watts on 240, 169 on 120
- Bullfrog X5L: 168 watts on 240, 154 on 120
What 240 volts buys you is speed, and on some tubs heating while you soak. Hot Spring's Jetsetter on 115 volts runs either the heater or the jet pump, never both. Jacuzzi's J315 and J325 on 120 volts won't heat while the jet pump runs either, and even on 240 volts it depends on how the tub is wired.
Chemicals
I don't have a monthly chemical figure I can stand behind, so this page doesn't give one. It depends on the sanitizer, how often the tub is used and by how many people, and none of the makers' manuals puts a number on it.
What does hold: dosing tired water costs more for less. The Pool & Hot Tub Alliance says high dissolved solids make sanitizer less effective, which is one more reason to change the water on your maker's interval.
Filters and water
These depend on your maker more than anything, and the makers' manuals give the intervals. Price your own cartridges and your own water against them.
Filter cartridges. Jacuzzi puts a cartridge's average life at about two years. Sundance says to replace its pleated filter every 18 months and the inner insert every 6. Bullfrog's flat Simplicity filter, in its A Series, needs replacing at least every 12 to 16 weeks. The filter guide has every maker's figures.
Water. Jacuzzi and Sundance say to change it about every three months, Hot Spring about every four, and Bullfrog every one to four months. Four fills of a 400 gallon tub is 1,600 gallons a year. Your water bill gives the rate, usually per 1,000 gallons or per hundred cubic feet, which is 748 gallons.
Go deeperWhen the water is actually dueEach maker's interval, and the dissolved-solids test that says drain now.The parts that wear out
None of these shows up monthly, and none comes with a published price I can verify for every tub. What the manuals do say:
- The cover: no maker gives it a life. The lift test above tells you when.
- Suction covers: Jacuzzi's and Sundance's manuals say they must be replaced every seven years.
- Ozone: Jacuzzi's control panel counts down to when its ozone unit needs replacing, and Bullfrog says to ask your dealer about maintaining and replacing its ozone parts.
- Pumps, the heater and the control board: no maker's manual gives them a life. Check what your warranty covers and for how long before you need to know.
Where the savings are
- Fix or replace a waterlogged cover. The CEC calls the cover and insulation the greatest opportunity to save energy in a spa.
- Add a floating blanket. Another barrier against heat loss and evaporation, working every night.
- Pick a single or insulated hinge when you replace the cover.
- Drop the set temperature a degree or two. 100°F instead of 102°F is a permanent reduction in loss rate, and 100°F is the figure the CPSC calls safe for a healthy adult.
- Shift heating and filtering off-peak, if your utility charges by time of use.
- Shelter it from wind. Wind strips heat off a cover, and a fence or screen on the prevailing side helps in an exposed yard, for the same reason it matters on a pool.
What is not on that list is switching sanitizer, or buying premium chemicals, or anything sold as an energy-saving additive. The bill is thermal. Fix the thermals.
Frequently asked questions
How much does it cost to run a hot tub per month?
Work it out from the tub's certified standby wattage: watts × 8,760 ÷ 1,000 gives kWh a year, and your rate turns that into dollars. The DOE's average for a standard spa in California's database is 194 watts. At the 2026 US average residential rate of 18.19 cents, that is about $309 a year, or $26 a month, before soaking and cold weather. The same tub costs about $786 a year at Hawaii's rate and $219 at Nebraska's.
Is it cheaper to leave a hot tub on all the time?
No, though the difference is small. Turning it down always saves some energy, because reheating only puts back heat the tub lost while it cooled, and a cooler tub loses heat more slowly. On a tub using the DOE's average 194 watts, a ten-degree drop in 50°F air saves just under one kWh a day. For a weekend, that is not much against a tub that takes hours to warm back up. For a trip, Hot Spring and Bullfrog both say to turn it down to about 80°F.
Does a 240V hot tub cost more to run than a 120V one?
No. California's database lists several tubs certified both ways, and the standby figures match closely: Bullfrog's A6 is 166 watts on either supply, and its X6R is 166 on 240 volts and 169 on 120. A 240V tub heats faster, and on some it can heat while the jets run. Hot Spring's Jetsetter on 115 volts runs either the heater or the jet pump, never both.
What uses the most electricity in a hot tub?
Holding the water at temperature. The California Energy Commission estimates that standby, which covers keeping the set temperature and filtering, is about 75 percent of the energy a spa uses over its life. The rest is heating a fresh fill and running the jets. That is why the cover and the insulation matter more than anything you change on the control panel.
How can I reduce my hot tub electricity bill?
Start with the cover. The CEC says foam that absorbs water loses nearly all its insulating value, so a cover that has got heavier is costing you. A floating blanket under it adds another barrier against heat loss and evaporation. If you're replacing the cover, the CEC notes that a single hinge or an insulated hinge loses less heat than the usual uninsulated fold. Then lower the set temperature a degree or two, and if your utility charges by time of use, find out when heating costs least.
