What a pool heat pump costs to run
About $10.75 per million BTU delivered at US average rates — and here is exactly what moves that number.
Quick picks
The heat pump, and the hundred-dollar purchase that changes its running cost more than any setting does.
| # | Product | Best for | Price |
|---|---|---|---|
| 1 | No photo The machine in question Hayward HeatPro Pool Heat Pump Rated by delivered output, unlike a gas heater. What you see is what goes into the water. | Lowest running cost per degree when you want real temperature control | |
| 2 | No photo The biggest lever on this number Sun2Solar 1200 Series Crystal Clear Solar Cover Everything here scales with your overnight loss. Cut the loss, cut the bill. | Most pools, most budgets — the default recommendation |
#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.
The derivation
A heat pump does not make heat. It moves heat that already exists in the outside air into your pool, and the ratio of heat delivered to electricity consumed is its coefficient of performance. That single number is what makes electricity — the most expensive energy you can buy per BTU — into the cheapest way to heat a pool.
| Electricity: $0.1834 per kWh (EIA, June 2026) | |
| 1 kWh = 3,412 BTU (EIA) | |
| $0.1834 ÷ 3,412 x 1,000,000 | = $53.75 per million BTU purchased |
| ÷ coefficient of performance 5.0 |
$10.75 per million BTU delivered into the water
COP 5.0 is our assumption, not a published figure — see below for what it does when it moves. Manufacturers publish COP at warm test conditions where it looks best.
What that means in practice
| Job | BTU | Cost |
|---|---|---|
| Raise 20,000 gal by 1°F | 166,600 | $1.79 |
| Raise 20,000 gal by 10°F | 1,666,000 | $17.91 |
| Replace a 3°F overnight loss (20,000 gal) | 499,800 | $5.37 |
| Same, for a 30-day month | 14,994,000 | $161.19 |
| Same, for a 150-day season | 74,970,000 | $805.95 |
The two inputs that move the answer
1. Your electricity rate
We use the US residential average of 18.34 cents per kWh, and residential electricity varies roughly threefold across US states. That is a bigger swing than anything else in this calculation.
| Your rate | Per million BTU | A 3°F overnight recovery |
|---|---|---|
| 10 c/kWh | $5.86 | $2.93 |
| 15 c/kWh | $8.79 | $4.39 |
| 18.34 c/kWh (US average) | $10.75 | $5.37 |
| 25 c/kWh | $14.65 | $7.32 |
| 35 c/kWh | $20.52 | $10.25 |
Your rate is on your bill. Put it into the running cost calculator rather than using our average.
2. Coefficient of performance, which falls in cold air
This is the one people are not told about. A heat pump extracts heat from the outside air, so as the air cools there is less heat available and the machine works harder for less. Its COP falls — and it falls precisely in the shoulder season, which is when you most want it.
| COP | Per million BTU delivered | A 3°F overnight recovery |
|---|---|---|
| 6.0 (warm, best case) | $8.96 | $4.48 |
| 5.0 (our assumption) | $10.75 | $5.37 |
| 4.0 | $13.44 | $6.72 |
| 3.0 (cool air) | $17.92 | $8.95 |
| 2.0 (cold air) | $26.88 | $13.43 |
Even at COP 2.0 — a genuinely poor day — a heat pump is still cheaper per delivered BTU than an electric resistance heater by half, and roughly comparable to natural gas. The advantage narrows in the cold; it does not disappear.
The lever that beats every setting
Every number on this page is a multiple of your pool’s heat loss. You can spend a long time optimizing the supply side, or you can reduce the demand side and shrink all of it at once.
DOE puts about 70% of pool heat loss down to evaporation, and the saving from covering a pool when it is not in use at 50 to 70% of heating cost. Against a season’s heat pump running cost of $805.95 in the example above, a hundred-dollar cover pays for itself in a matter of weeks — and then keeps paying, every season, for years.
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 September 2, 2026.
Sun2Solar 1200 Series Crystal Clear Solar Cover
The value pick, and the one whose logic actually holds up. A clear cover transmits more sunlight into the body of the pool instead of absorbing it at the surface, and 12 mil is the point where lifespan stops being the limiting factor. Bob Vila measured this and the 16-mil blue at the same 4 to 5 degrees in an hour, so you are paying less for the same measured result and giving up some years of service life.
Best for Most pools, most budgets — the default recommendation
| Thickness | 12 milThe manufacturer publishes no retrievable specification sheet; figure is as listed at retail. | Retail listing |
|---|---|---|
| Color | Clear | Retail listing |
| Stated lifespan | 3 to 4 years for the 12-mil clear tierSwim University's published figure for 12-mil clear covers generally. | Retail listing |
| Bubble side | Bubbles face the water | Published standard |
4 to 5 degrees F in one hour
Claimed by Bob Vila, measured across all covers in their group. Conditions: One hour under 2pm sun on 89 to 92 degree F days. Source
- Clear transmits more light into the water instead of stopping it at the surface
- 12 mil is the sweet spot: real service life without 16-mil bulk
- Cheaper than the 16-mil tier with no measured heating penalty
- Shorter published lifespan tier than 16 mil
- A clear cover shows algae and debris more obviously, which some people dislike
- Whether clear genuinely outlasts or under-lasts blue in the same thickness
- Real-world tear resistance at a pool with rough edges
- How much the clear material clouds over a season of UV
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
How much does it cost to run a pool heat pump?
What is COP on a pool heat pump?
Does a pool heat pump cost more to run in cold weather?
- 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
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