What a pool heater really costs
The sticker price is the part everybody compares and the part that matters least. Here is the ten-year view.
Quick picks
Ranked on total cost of ownership rather than purchase price, which flips the order almost completely.
| # | Product | Best for | Price |
|---|---|---|---|
| 1 |  Cheapest to own Hayward HeatPro Pool Heat Pump Higher purchase price, and it wins on total cost within a couple of seasons of steady use. | Lowest running cost per degree when you want real temperature control | |
| 2 | No photo Cheapest to own, full stop SmartPool SunHeater S601P Solar Heating System Nothing to run means nothing to add to the purchase price. Ever. | Adding real heat with no running cost, on a sunny site | |
| 3 |  Cheapest to buy that is still sensible Raypak Digital Natural Gas Pool Heater Lower up front and lower install if you already have a gas line. | Heating fast and occasionally, rather than holding a temperature | |
| — | No photo The false economy An electric resistance pool heater Lowest sticker price, highest total cost by a wide margin on a full-size pool. | Spas and very small above-ground pools only |
#ad We earn a commission if you buy through this link, at no extra cost to you. It never changes the ranking. How this site is funded. Prices last checked October 18, 2026.
Three costs, and only one gets compared
A heater costs you money three times: when you buy it, when you install it, and every time it runs. Listing pages compare the first, occasionally mention the second, and never quantify the third — which is the one that dominates over the life of the equipment.
We are not going to publish purchase prices here, and that is deliberate: equipment prices move constantly, and a number typed into an article goes stale silently. What we can give you is the part that does not move — the running-cost arithmetic — and a structure for putting your own quotes into it.
The running cost, per fuel
| Method | Per million BTU | Multiple of a heat pump |
|---|---|---|
| Solar panels | $0.00 | 0x |
| Electric heat pump | $10.75 | 1.0x |
| Natural gas | $28.36 | 2.6x |
| Propane | $35.66 | 3.3x |
| Electric resistance | $53.75 | 5.0x |
From EIA US average residential energy prices with our stated equipment assumptions. Your rates change these; the calculator takes them.
Turning that into an annual number
You need one measurement: how many degrees your pool drops overnight. Two thermometer readings, dusk and dawn, a foot down and away from the returns.
| Nightly loss BTU = gallons x 8.33 x your overnight drop | |
| Annual BTU = nightly loss x days you heat | |
| Annual cost = (annual BTU ÷ 1,000,000) x delivered rate |
Worked example: 20,000 gal, 3°F drop, 150 days
499,800 BTU a night x 150 = 74,970,000 BTU a year. At heat pump rates that is $805.95; at natural gas rates $2,125.94; at electric resistance rates $4,029.75. That is the number to put beside the purchase prices you have been quoted.
Ten years, which is the honest horizon
| Method | Per season | Over 10 seasons |
|---|---|---|
| Solar panels | $0 | $0 |
| Electric heat pump | $805.95 | $8,059.49 |
| Natural gas | $2,125.94 | $21,259.39 |
| Propane | $2,673.26 | $26,732.64 |
| Electric resistance | $4,029.75 | $40,297.47 |
Running cost only — no purchase, no install, no maintenance, and no allowance for energy prices changing over a decade. It is a like-for-like comparison of the fuel side, which is the part nobody publishes.
Install costs, honestly
We cannot quote these — they are entirely local and depend on your property. What we can tell you is where the money hides:
- Gas heater: the gas line. An existing line is often not sized for a pool heater’s draw, and running a new one is frequently the largest single item on the quote. Get this priced before you commit to gas.
- Heat pump: the electrical circuit and a level pad. Usually simpler than a gas line, sometimes not.
- Solar panels: the plumbing run and the mounting. A ground-level installation is much cheaper than a roof one.
- Electric resistance: often nothing, which is precisely what makes it tempting. Check the amperage against your circuit before assuming it plugs in.
If the question underneath all of this is simply whether a heater is worth buying at all, we answer that directly — it comes down to three numbers, two of which you can measure in a week.
Those are the costs of a first install. A replacement is a different calculation, because most of that infrastructure already exists and the question becomes which parts of it carry over — replacing a pool heater sets out what you keep in each scenario.
The purchase that changes all of these numbers
Every figure on this page scales with your overnight loss. Cut that loss and every column falls proportionally.
DOE puts the heating-cost saving from covering a pool when it is not in use at 50 to 70%. Against a ten-year running cost in the thousands, a hundred-dollar cover is the highest-return line item in this entire subject — and it also lets you buy a smaller heater, which saves you again at purchase.
Once you know the gap a heater has to close, our ranked picks across every heater type set out which technology closes it for the least money over ten years, rather than the least money on the day.
Every pick, in detail
What each one publishes, what is good and bad about it, and — the section this category usually omits — what we could not judge without owning one.
Hayward HeatPro Pool Heat Pump
If you are heating a pool with electricity, this is the shape of machine to do it with. A heat pump moves heat instead of making it, and at the assumptions we publish it delivers a million BTU into the water for about a fifth of what an electric resistance heater costs to deliver the same. It is slower than gas and it fades as the air gets colder, which is exactly when you want it — that trade is the whole decision.
Best for Lowest running cost per degree when you want real temperature control
| Type | Air-source heat pumpThe manufacturer publishes no retrievable specification sheet; figure is as listed at retail. | Retail listing |
|---|---|---|
| Rating convention | Rated by BTU/hr OUTPUTThis is the trap in the category. Gas heaters are rated by fuel INPUT, heat pumps by heat OUTPUT. A 140,000 BTU heat pump and a 140,000 BTU gas heater do not deliver the same heat. | Published standard |
| Cost per million BTU delivered | About $10.75 at our published assumptionsUS average residential electricity at 18.34 cents/kWh (EIA, June 2026) and an assumed COP of 5.0. Both are substitutable on our running-cost calculator. | Our arithmetic |
- Cheapest running cost per delivered BTU of any controllable heater
- No gas line, no combustion, no flue
- Holds a set temperature rather than depending on the weather
- Slow — expect most of a day to move a full-size pool ten degrees
- Efficiency falls with air temperature, so it is weakest in the shoulder season
- High purchase price against a gas heater of comparable output
- The COP this specific unit achieves at your conditions
- Compressor and control-board longevity
- Noise at the distance your deck actually sits from it
These need a unit in hand across a season. We do not have one, so we do not have an opinion worth printing on them.
#ad We earn a commission if you buy through this link, at no extra cost to you. It never changes the ranking. How this site is funded. Prices last checked October 18, 2026.
SmartPool SunHeater S601P Solar Heating System
Solar panels that plumb into the return line and heat the water with sunlight rather than fuel, which puts their running cost at zero — the only entry in the whole heating category where that is true. The trade is that you cannot dial in a temperature: the panels deliver what the sun gives them on the day, and on a cloudy week they deliver very little.
Best for Adding real heat with no running cost, on a sunny site
| Type | Roof, rack or ground-mounted solar collector panels, plumbed inline | Manufacturer |
|---|---|---|
| Collector area | Two 2 x 20 ft panels, 80 sq ft totalThis is the number to size from. The trade rule of thumb is collector area equal to 50-100% of the pool's surface, so a 16 x 32 pool needs several of these systems rather than one. | Manufacturer |
| Material | Polypropylene, stated not to corrode or scale | Manufacturer |
| Also required | One SK21 System Installation Kit per installation, sold separatelyThe manufacturer's own wording. One SK21 serves up to four of these two-panel systems. The panels on their own are not a complete installation, which is the commonest surprise in this product category. | Manufacturer |
| Running cost | $0 in fuelThe circulation pump is already running for filtration. There is no additional fuel or electricity cost attributable to the heat. | Our arithmetic |
Up to 6 to 10 degrees F
Claimed by SunHeater, on its own product page for the S601P. Conditions: Stated as under favorable conditions; no time period given. Source
Worth reading beside the figure below. The manufacturer's own claim for this product is 6 to 10 degrees. The retail listings for the same model say up to 15. The larger number is the one further from the manufacturer.
As much as 15 degrees F
Claimed by Bob Vila, describing the S601P. Conditions: Stated as requiring ample sunlight; no time period given. Source
Note the phrasing: with ample sunlight it can boost temperature by as much as 15 degrees. That is a cumulative ceiling reached over days of good sun, not a figure you will see in an afternoon.
- Zero fuel cost, forever — nothing else in this category can say that
- No combustion, no gas line, no additional electrical service
- Panels can be added to as the budget allows
- You get the sun's schedule, not yours
- Needs real unshaded mounting area, and plumbing work to install
- Does nothing on a cold cloudy week, which is when you most want it
- Actual heat output at your latitude, roof pitch and shading
- How the panel material survives a decade of UV and freeze cycles
- Whether the included fittings suit your existing plumbing
These need a unit in hand across a season. We do not have one, so we do not have an opinion worth printing on them.
#ad We earn a commission if you buy through this link, at no extra cost to you. It never changes the ranking. How this site is funded. Prices last checked October 18, 2026.
Raypak Digital Natural Gas Pool Heater
The right answer when speed matters more than running cost — a weekend pool you want warm on Friday afternoon rather than one you hold at temperature all season. At the assumptions we publish, gas costs roughly two and a half times what a heat pump costs per delivered BTU, and it will get there in a fifth of the time. Buy the speed if you need the speed.
Best for Heating fast and occasionally, rather than holding a temperature
| Type | Natural gas or propane fired, digital controlThe manufacturer publishes no retrievable specification sheet; figure is as listed at retail. | Retail listing |
|---|---|---|
| Rating convention | Rated by BTU/hr INPUTA 400,000 BTU gas heater burns 400,000 BTU an hour and delivers roughly 82% of it. Do not compare that number directly against a heat pump's output rating. | Published standard |
| Cost per million BTU delivered | About $28.36 at our published assumptionsUS average residential natural gas at $24.09/Mcf (EIA, June 2026) and an assumed 82% thermal efficiency. | Our arithmetic |
- Fast — hours rather than most of a day on a full-size pool
- Works the same in cold air, unlike a heat pump
- Lower purchase price than a heat pump of equivalent real output
- Roughly two and a half times a heat pump's cost per delivered BTU
- Needs a gas line sized for it, which is often the real cost
- Propane instead of natural gas raises the running cost by about a quarter again
- The efficiency this specific unit achieves in service
- Heat exchanger life against your water chemistry
- Whether your existing gas supply can feed it without an upgrade
These need a unit in hand across a season. We do not have one, so we do not have an opinion worth printing on them.
#ad We earn a commission if you buy through this link, at no extra cost to you. It never changes the ranking. How this site is funded. Prices last checked October 18, 2026.
An electric resistance pool heater
Skip it for a full-size pool, and the arithmetic is not close. At the same electricity price, a resistance heater costs about five times what a heat pump costs to deliver the same heat, because it makes heat instead of moving it. It has a legitimate niche on a small above-ground pool or a spa where the volume is tiny and the install is a plug. On 20,000 gallons it is the most expensive way to heat water that exists.
Best for Spas and very small above-ground pools only
| Cost per million BTU delivered | About $53.75 at our published assumptionsUS average residential electricity at 18.34 cents/kWh (EIA, June 2026) at a coefficient of performance of 1.0. Compare with about $10.75 for a heat pump on the same electricity. | Our arithmetic |
|---|---|---|
| Efficiency | About 1:1 — no efficiency to argue about | Published standard |
- Cheap to buy and often just plugs in
- Genuinely sensible on a spa or a very small pool
- About five times a heat pump's running cost for identical heat
- Draws serious current, which frequently means an electrical upgrade
- On a full-size pool the running cost is punishing
- Element life in your water chemistry
- Whether your existing circuit can carry it
These need a unit in hand across a season. We do not have one, so we do not have an opinion worth printing on them.
#ad We earn a commission if you buy through this link, at no extra cost to you. It never changes the ranking. How this site is funded. Prices last checked October 18, 2026.
Questions people actually ask
How much does a pool heater cost to run?
Which pool heater is cheapest overall?
Why don't you publish pool heater prices?
- Average retail price of electricity to US residential customers: 18.34 cents/kWh, June 2026U.S. Energy Information Administration · read 2026-09-02
- US residential natural gas price: $24.09 per thousand cubic feet, June 2026U.S. Energy Information Administration · read 2026-09-02
- US residential propane price: $2.674 per gallon, week ending 30 March 2026U.S. Energy Information Administration · read 2026-09-02
- Energy content conversion factors: 3,412 BTU per kWh, 1,036 BTU per cubic foot of natural gas, 91,452 BTU per gallon of propaneU.S. Energy Information Administration · read 2026-09-02
- U.S. Department of Energy pool-energy figures (evaporation share, BTU per pound evaporated, cover savings, recommended temperatures, wind effect)Recreonics, reproducing and attributing the U.S. Department of Energy · read 2026-09-02
- Pool heater roundup: the 8.33 BTU per gallon per °F figure, attributed on the page to Alicia Toedter of Leslie'sBob Vila · read 2026-09-02
Every URL above was fetched and returned content on the date shown. Where a figure is ours rather than somebody else’s, the arithmetic is on the page and on the methodology page. If you find an error in it, we would genuinely like to know.
Read next
Replacing a pool heater
What carries over from the old heater and what does not, why matching the old BTU is usually wrong, and why a replacement is the one affordable moment to switch fuel.
How long do pool heaters last?
Lifespan by heater type, the components that actually fail, what the warranties really cover, and how that should change what you buy in the first place.
Is a pool heater worth it?
The pre-purchase doubt, answered with arithmetic: what a heater costs to run per week of swimming you actually gain, when the honest answer is no, and the cheaper thing to try first.
Which pool heater to buy
Every type of pool heater ranked on what it costs to deliver a million BTU into the water, how many hours it needs to do it, and what the install actually involves.
How much does it cost to heat a pool?
The complete cost model: what a million BTU costs to deliver with each fuel, what that means per degree and per pool size, and why heat-up cost is not your monthly bill.
What a pool heat pump costs to run
The heat pump running-cost derivation, what happens to it in cold air, and the two inputs that change the answer more than anything else.
What size pool heater do I need?
How to size a heater from your pool's actual energy requirement, the input-versus-output rating trap, and why the answer gets smaller once you own a cover.
Heat pump vs gas pool heater
The two options priced per delivered BTU and timed on the same pool, with the one question that decides which trade suits you.
Does a solar cover pay for itself?
The full payback derivation from one measurement you can take tonight, plus a sensitivity table for people whose pool is nothing like the example.