So, how much does it cost to run a hot tub? For a covered, well insulated tub, the bill comes down to one formula: average watts the tub draws, times hours in a month, times your electricity rate. By our math, a tub averaging 150 to 250 watts costs roughly $20 to $33 a month at the July 2026 US average residential rate, and about double that in California. Below: where those numbers come from, what pushes them up, and how our tubs compare.
If you are still deciding how to wire your spa, read our 110V vs 240V hot tub guide first. It covers heater wattage and heat-up speed; this article focuses on the monthly bill.
How much does it cost to run a hot tub? The formula
Monthly cost = average watts x 730 hours / 1,000 x your price per kWh. A month has about 730 hours, so every 100 watts of average draw adds about 73 kWh to your bill.
Your rate is the part you cannot change. The US Energy Information Administration’s Electric Power Monthly Table 5.6.A lists the average residential price for July 2026 at 18.31 cents per kWh nationally. A few states for comparison: Washington 14.71 cents, Texas 15.88, Colorado 17.00, New York 29.90 and California 33.61. Use the rate on your own bill.
Hot tub electricity cost per month: worked examples
The table below is our own math, not a manufacturer figure or a measured average. Each row assumes the tub draws that many watts on average, around the clock, for a 730 hour month.
| Average draw | kWh per month | Washington (14.71 cents) | US average (18.31 cents) | California (33.61 cents) |
|---|---|---|---|---|
| 150 watts | 109.5 | $16.11 | $20.05 | $36.80 |
| 250 watts | 182.5 | $26.85 | $33.42 | $61.34 |
| 400 watts | 292 | $42.95 | $53.47 | $98.14 |
Which row fits depends on insulation, cover, climate, set temperature and soak time. There is no single honest “average”, so treat the 400 watt row as a cold weather or heavy use scenario, not a typical one.
What California’s standby rule tells you
California’s appliance efficiency rules (Title 20, section 1605.3, which you can read on Cornell’s Legal Information Institute) cap the standby power of portable electric spas made on or after June 1, 2019. For a standard spa, the maximum normalized standby power is 3.75 x V^(2/3) + 40 watts, where V is the fill volume in gallons. The measurement is normalized to a 37 F gap between average water and air temperature. The test method is ANSI/APSP/ICC-14 2019, per section 1604.
Plugging in our listings’ capacities, by our math the ceiling works out to about 117 watts for a 350 liter (about 92 gallon) tub, 184 watts for 900 liters, 214 watts for 1,200 liters and 252 watts for a 425 gallon tub. That is a legal maximum under test conditions, not a promise of what any tub uses in your yard. Colder air, an open cover or long soaks all add to it.
Hot tub energy use: the drivers that move your bill
Standby heat loss
Most of the time your tub just sits, holding temperature. Insulation and the cover decide how much heat leaks out. American Spas’ owner’s manual states plainly that covered spas use less electricity maintaining the set temperature, and that keeping the spa covered is required to maintain warranty coverage.
Soaking time
With the cover off and jets running, heat escapes fast and the heater has to catch up later. By our math, reheating a 425 gallon tub by 2 F takes about 2.1 kWh, roughly 38 cents at the US average rate. Frequent long soaks add up.
The first fill
Heating fresh water is the big one time hit. By our math, raising 425 gallons from 55 F to 102 F takes about 49 kWh, around $8.94 at 18.31 cents, before heat loss. Each drain and refill repeats that cost.
Set temperature and climate
The bigger the gap between water and air, the more heat you lose. A tub in a Minnesota winter works harder than the same tub in Arizona. The CPSC has long advised that hot tub water should never exceed 104 F, so there is no reason to run hotter than that.
How to lower hot tub running costs
- Keep the cover on and in good shape. A waterlogged or warped cover leaks heat. See our hot tub cover replacement guide for signs it is time.
- Buy the size you will use. More water means a higher standby ceiling and a bigger first heat. Our hot tub sizes guide helps match seats to space.
- Get the base right. A level, solid pad protects the shell and cabinet seal. Our hot tub foundation guide covers options.
- Lower the set point when away. A few degrees less narrows the water to air gap.
- Watch summer thermal creep. American Spas’ manual notes that in hot weather a well insulated tub can climb above its set temperature, and suggests venting or opening the cover.
Tubs we carry: specs that affect running cost
Specs come from our product listings; prices were checked in October 2026, so confirm the live price on each page. Capacities are converted from liters where the listing gives liters.
| Model | Power | Heater | Water | Cover and insulation (per listing) | Our price |
|---|---|---|---|---|---|
| Canadian Spa Yukon 2 Person | 120V, 15A | 1.5 kW | 350 L | 5″/3″ hardtop, Blackout insulation | $7,749 |
| Canadian Spa Muskoka 5 Person | 120V, 15A | 1.0 kW | 900 L | 3″/2″ hardtop, Blackout insulation | $6,000 |
| Canadian Spa Richmond 6 Person | 120V, 15A | 1.5 kW | 900 L | 5″/3″ hardtop, Blackout insulation | $10,249 |
| Canadian Spa Cambridge 6 Person | 240V, 50A | 5.5 kW | 1,000 L | 5″/3″ hardtop, Blackout insulation | $7,999.99 |
| Canadian Spa Thunder Bay SE 6 Person | 240V, 50A | 5.5 kW | 1,200 L | 5″/3″ hardtop, 7 insulation layers | $13,249 |
| American Spas AMZ618L Dual Voltage | 120V or 240V (40A) | 1.5 kW or 5.5 kW | 425 gal | Hydro-Armor tapered cover, Thermo-Shield | $7,100 |
| American Spas AMZ740L Lounger | 240V | 5.5 kW | 425 gal | Hydro-Armor tapered cover, Thermo-Shield | $7,300 |
Heater size changes how fast a tub recovers, not the energy needed to hold temperature. Note the Muskoka’s thinner 3″/2″ cover compared with the 5″/3″ covers on the other Canadian Spa models. Canadian Spa Company’s own site describes its full foam “Black Out” insulation as keeping heat in and running costs down; that is the maker’s claim. Browse more on our Canadian Spa Company brand page and American Spas brand page.
Price honesty: American Spas sells direct at americanspas.com, and when we checked, the AMZ618L ($7,100) and AMZ740L ($7,300) were the same price there as here, with free shipping. Canadian Spa Company’s US site listed swim spas but not these hot tubs; its Canadian site sells them in Canadian dollars, so prices are not directly comparable. We offer free freight shipping on orders of $999 or more. Returns follow our return and refund policy.
Frequently asked questions
What is a typical hot tub electricity cost per month?
There is no single honest figure. By our math, a tub averaging 150 to 250 watts costs about $20 to $33 a month at the July 2026 US average rate of 18.31 cents per kWh. Plug in your own rate.
Does a 120V plug and play tub cost less to run?
Not automatically. Voltage changes how fast the heater works, but holding temperature depends on insulation, cover and climate. Our 110V vs 240V guide explains the tradeoffs.
What is the best way to lower hot tub running costs?
Keep a tight, dry cover on whenever the tub is not in use, lower the set point when you are away, and shield the tub from wind.
How hot should I keep the water?
The CPSC advises never exceeding 104 F. American Spas’ manual says people with heart disease, blood pressure or circulatory problems should consult a physician first, and pregnant women should check with their doctor before use.
The bottom line
Running cost is watts x hours x rate. Find your rate on your bill, pick a realistic wattage from the table, and you have a fair estimate. A good cover, a right sized tub and sensible temperatures do most of the saving. Questions about a specific model? Call us at 866-777-2590, Monday to Friday, 9AM to 6PM PST, or browse more guides in our buying guides.
