Heaters for above-ground pools
The arithmetic is far kinder at 7,000 gallons than at 20,000, which changes what is worth buying.
Quick picks
Ranked for a soft-sided or frame above-ground pool, where volume is small enough to change which trade-offs matter.
| # | Product | Best for | Price |
|---|---|---|---|
| 1 | No photo Best overall for above-ground SmartPool SunHeater S601P Solar Heating System Zero running cost, and a small pool is exactly the size solar panels handle well. | Adding real heat with no running cost, on a sunny site | |
| 2 | No photo Do this first Intex Easy Set Solar Cover Cheapest possible intervention, and a small pool loses heat proportionally faster. | Intex and other soft-sided above-ground pools | |
| 3 | No photo If you want a thermostat Hayward HeatPro Pool Heat Pump Overkill for a paddling pool, right for a permanent above-ground pool you use all season. | Lowest running cost per degree when you want real temperature control | |
| 4 | No photo The one place this is defensible An electric resistance pool heater On a very small pool the running cost penalty is survivable and the install is a plug. | Spas and very small above-ground pools only |
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Why small pools are a different problem
Everything in pool heating scales with volume, and an above-ground pool has far less of it. The energy needed to raise the temperature scales directly, so the same ten degrees costs roughly a third of what it costs on a full-size inground pool.
| 20,000 gal x 8.33 x 10°F | = 1,666,000 BTU |
| 7,600 gal x 8.33 x 10°F | = 633,080 BTU |
An 18-foot above-ground pool needs about 38% of the energy
At a heat pump's $10.75 per million BTU delivered, that is about $6.81 against $17.91. On natural gas, about $17.95 against $47.24.
There is a second effect working in the same direction: a shallow pool has a lot of surface area for very little water, so sunlight moves the temperature roughly 70% faster than it moves a deep inground pool. The arithmetic is here.
The catch is that both effects run in reverse at night. A small pool cools faster too, which makes a cover more valuable rather than less.
What that means for what to buy
Solar panels are unusually well matched here
Collector sizing guidance runs at roughly 50 to 100% of pool surface area. On a 254-square-foot round pool that is a manageable amount of panel — often a couple of mats on a rack beside the pool rather than a roof install. And the plumbing is simpler, because an above-ground pool’s equipment is at ground level and accessible.
A heat pump is right for a permanent pool
If your above-ground pool is a steel-wall installation that stays up year-round and gets used all season, a heat pump makes as much sense here as on an inground pool — cheapest controllable heat at about $10.75 per million BTU delivered. It is overkill for a seasonal soft-sided pool that comes down in September.
Electric resistance: the one defensible case
We tell people to skip electric resistance heaters on a full-size pool, and we mean it — $53.75 per million BTU is roughly five times a heat pump on the same electricity. But on a small above-ground pool the absolute numbers stay survivable, the units are cheap, and many of them genuinely just plug in.
| 7,600 gal x 8.33 x 5°F | = 316,540 BTU |
| x $53.75 per million BTU | = $17.01 |
| The same job on a heat pump | = $3.40 |
A five-degree bump costs about seventeen dollars on resistance and about three and a half on a heat pump. On a pool this size the difference is real but not ruinous, and the heat pump costs several times more to buy. That is a defensible trade on a small pool and an indefensible one on 20,000 gallons.
What to skip
A large gas heater. The purchase price, the gas line and the installation are sized for an inground pool, and on 7,600 gallons you are paying for capacity you cannot use. If you want speed on a small pool, a modestly sized heat pump gets there fast enough because there is so little water to move.
The order to do it in
- Cover the pool. Small pools lose heat proportionally faster and this is the cheapest possible fix.
- Put the pool somewhere unshaded if you have any choice, and shelter it from wind — DOE puts a 7 mph breeze at a 300% increase in energy consumption.
- Then heat. Solar first if your site suits it, a heat pump if you want control, and resistance only if the pool is genuinely small.
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.
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 or ground-mounted solar collector panels, plumbed inlineThe manufacturer publishes no retrievable specification sheet; figure is as listed at retail. | Retail listing |
|---|---|---|
| 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 |
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 September 2, 2026.
Intex Easy Set Solar Cover
Made to fit Intex's own above-ground pools, which is the entire reason to buy it: on a soft-sided pool, a cover that matches the frame diameter is worth more than a thicker cover that does not. It is a thin cover and it will not last like a 12-mil blanket, but on a 5,000-gallon above-ground pool the physics are in your favor anyway, because there is far less water to move.
Best for Intex and other soft-sided above-ground pools
| Fits | Sized to Intex Easy Set and metal-frame pool diametersThe manufacturer publishes no retrievable specification sheet; figure is as listed at retail. | Retail listing |
|---|---|---|
| Color | Blue | Retail listing |
| Bubble side | Bubbles face the water | Published standard |
- Actually fits the pool it is made for, which most generic rounds do not
- Cheap enough to replace on the schedule a thin cover needs
- On a small pool the same sunlight moves the temperature several times faster
- Thin. Expect a season or two, not five
- Sized to Intex diameters, so it is a poor buy for anything else
- Actual thickness — Intex publishes no mil rating we could retrieve
- How it holds up to the sun in a hot climate over one full season
- Whether the fit is as close on the metal-frame pools as on the Easy Sets
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 September 2, 2026.
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 September 2, 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 September 2, 2026.
Questions people actually ask
What size heater do I need for an above-ground pool?
Is it cheaper to heat an above-ground pool?
Can I use an electric pool heater on an above-ground pool?
- 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
Solar covers for above-ground pools
Why fit matters more than thickness on an above-ground pool, and the arithmetic showing why a small pool responds several times faster to the same sunlight.
Solar pool heaters
Solar collector panels: zero fuel cost forever, at the price of getting the sun's schedule instead of your own. Ranked, with the trade stated plainly.
How to heat a pool
The complete walkthrough: what your pool actually needs in BTU, every heating option priced per delivered million BTU, and the order to try them in.
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.
The cheapest way to heat a pool
Cheapest to buy is a cover. Cheapest to run is solar, then a heat pump. The arithmetic for both, and a spending order that works at any budget.