How Many Watts Does a Heat Pump Use?

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A ductless mini-split heat pump draws roughly 500W to 2,000W while it is running, and the size of the unit decides where in that range it falls: a small single-zone 9,000 BTU head sits near the bottom, a 24,000 BTU head near the top. A whole-home ducted system pulls several times that. And if the outdoor unit cannot pull enough heat out of cold air, the electric resistance strips that back it up can add 10,000W or more on their own — often the real reason a heat pump home’s January bill doubles. Those three numbers rarely appear on the same page, which is most of what makes heat pump wattage confusing.

Mini-split running wattage by size

Manufacturer spec sheets list running watts for each mini-split size, and the figures below are typical mid-range values — close to the rated heating inputs on one maker’s spec sheets (named examples follow below). Inverter units modulate, so a running unit can sit well below its rated input in mild weather, and on those sheets the maximum heating input runs about 1.5 to 1.75 times the rated figure. Units under about 12,000 BTU are commonly wired at 115V, though many, including the Mitsubishi 9,000 and 12,000 BTU models below, are 208/230V; 18,000 BTU and up are almost always 208/240V.

If your unit is a single-zone model rated at 115V rather than 240V, do not assume the wattage is lower — the amps are simply higher for the same wattage, per the standard formula (amps equal watts divided by volts, covered on our watts-to-amps calculator). Multi-zone systems, which run two to five indoor heads off one outdoor compressor, do not add up like separate single-zone units: the shared outdoor unit draws up to its own rated maximum input (listed on its spec sheet), and each wall-mounted indoor head adds only its fan and controls, roughly 20-60W.

Spec-sheet examples: Mitsubishi M-Series, 9,000 to 24,000 BTU

Mitsubishi Electric’s submittal data sheets for its wall-mounted M-Series heat pumps (an MSZ-GL indoor head paired with an MUZ-GL outdoor unit, 2022 editions) give two input figures for each size: a rated input, measured at a fixed compressor speed under AHRI test conditions, and a maximum input for when the compressor runs flat out. All four sizes run on 208/230V.

The rated heating inputs sit close to the typical figures in the first table. The maximums are the numbers to plan backup power around: the 18,000 BTU system can draw 2,455W and the 24,000 BTU system 3,592W. The same sheets list compressor locked-rotor amps only slightly above rated load amps, 7.7A against 6.7A on the 9,000 BTU outdoor unit, which fits the soft start described next.

Running amps vs starting amps

Every figure above is the running load — what the compressor draws once it has settled into steady operation. Most modern mini-splits use variable-speed, inverter-driven compressors that ramp up gradually from low speed, so they start with little or no inrush; to size a backup power source for one, use the maximum input watts on the unit’s spec sheet, which it can reach when working its hardest, rather than a startup surge. Only fixed-speed units surge: their compressors pull several times their running current for a fraction of a second at startup. It is the same mechanism that makes a refrigerator compressor the hardest thing in a house to power from a small inverter — see our refrigerator wattage breakdown for the numbers on that comparison.

Whole-home air-source heat pumps: a different scale entirely

A central, ducted air-source heat pump sized for an average house — roughly 3 to 4 tons — runs at 3,000W to 5,000W of electrical input once the outdoor compressor and the indoor air handler’s blower motor are both counted. At 240V that is 12.5A to 20.8A continuous. The circuit is not sized from those running amps or the general 80% rule. Under NEC Article 440, the wire must be rated for at least the minimum circuit ampacity (MCA) printed on the outdoor unit’s nameplate, which already includes the code’s margin for the compressor, and the breaker can be no larger than the nameplate’s maximum overcurrent protection (MOCP). Code editions vary with local adoption, so have a licensed electrician size and install the circuit.

Coefficient of performance: why the wattage understates the heat

A heat pump’s electrical draw is not a measure of how much heat it delivers, and that is the point of the technology. A resistance heater with a coefficient of performance (COP) of 1 turns every watt of electricity into a watt of heat. A heat pump with a COP of 3 moves three watts of heat — extracted from outdoor air, even cold outdoor air, by compressing and expanding refrigerant — for every watt of electricity it consumes. That multiplier is why a heat pump can heat a home on a fraction of the running wattage a baseboard resistance system would need for the same square footage.

COP is not fixed. It falls as the outdoor temperature falls, because there is less heat in the air to extract and the compressor has to work harder for the same output; how far it falls is model-specific. ENERGY STAR’s cold-climate label only requires a COP of at least 1.75 at 5°F. Mitsubishi lists a COP of 4.44 at 47°F for its 9,000 BTU MUZ-GL09NA system and 2.82 at 5°F with the compressor at maximum capacity, but only 1.89 at 5°F for the 24,000 BTU MUZ-GL24NA. A drop in COP does not show up as extra running watts on the compressor alone — it shows up as the system running for a larger share of every hour, and, below the point where the compressor can no longer cover the house’s heat loss, as the auxiliary strips switching on to close the gap.

The ratings that set the bill: SEER2 and HSPF2

Under the definitions ENERGY STAR publishes with its heat pump criteria, HSPF2 is the heat a system delivers over the heating season in BTU, divided by the electricity it uses in watt-hours, calculated for one standard climate (DOE’s Region IV). SEER2 is the same ratio for cooling: BTU of heat removed per watt-hour. A higher number means fewer kWh for the same comfort.

Split-system heat pumps manufactured on or after January 1, 2023 must reach at least 14.3 SEER2 and 7.5 HSPF2 under the federal standard in 10 CFR 430.32(c). ENERGY STAR asks more of a split system: at least 15.2 SEER2, 11.0 EER2 and 7.8 HSPF2. Its cold-climate tier raises the HSPF2 floor to 8.1 for ducted and 8.5 for ductless split systems, and adds low-temperature requirements, including the 1.75 COP at 5°F noted above and heating capacity at 5°F of at least 70% of capacity at 47°F. The four Mitsubishi systems above are rated 10.0 to 10.9 HSPF2 and 20.4 to 24.3 SEER2.

Auxiliary heat strips are where the bill spikes

The backup resistance strips built into most whole-home heat pump air handlers are sized in 5kW steps — 5,000W, 10,000W, 15,000W, sometimes 20,000W in a larger home — and they run at a COP of 1, no multiplier, full watts straight to heat. A 10,000W strip at 240V draws 41.7A on its own, on top of whatever the compressor and blower are already pulling, and it is wired on its own dedicated breaker for exactly that reason. Auxiliary strips are meant to run for short stretches while the compressor catches up, or during a hard freeze; a thermostat stuck on “emergency heat,” running the strips continuously instead of the compressor, can push a heat pump home’s winter bill well past what the running-watts figures above would predict.

How many kWh a heat pump uses per month

For a single mini-split, multiply running watts by hours of compressor run time and divide by 1,000. A 9,000 BTU unit averaging 700W for eight hours a day uses 5.6 kWh a day, about 168 kWh in a 30-day month, or roughly $30 at 18 cents per kWh. Run time varies with the weather and the thermostat setting.

For a whole house, start from the heat the house needs and divide by the seasonal rating: heating kWh = heat delivered in BTU ÷ (HSPF2 × 1,000), and cooling kWh = heat removed in BTU ÷ (SEER2 × 1,000). Resistance heat, aux strips included, gets no multiplier: one kWh yields 3,412 BTU, EIA’s standard conversion. For a month in which the house needs 10 million BTU of heat, about 13,900 BTU an hour on average:

The 18-cent rate is the US residential average for January to July 2026 (18.19 cents) in EIA’s Electric Power Monthly; your own rate is on your bill. Because HSPF2 is a season-long average for one test climate, a colder-than-average month in a colder region will use more than these figures.

For a survey-based reference, EIA’s 2020 Residential Energy Consumption Survey found that in 2020, US homes using electricity for space heating used an average of 2,484 kWh a year on it, including 518 kWh in January and 602 kWh in December. The Midwest averaged 3,109 kWh a year, and state averages ran from 423 kWh in Hawaii to 5,505 kWh in West Virginia. These averages combine every type of electric heating equipment and count homes where electricity is only a secondary heat source, so treat them as a broad range rather than a heat pump benchmark.

Can a portable power station run a heat pump?

For a mini-split, marginally, and only the smaller sizes. A large all-in-one unit such as the EcoFlow DELTA 3 Max Series Portable Power Station (2048Wh) (2,048 Wh) is rated by EcoFlow at 2,400W continuous (its X-Boost mode stretches to 3,400W, for resistive loads such as heaters) — enough continuous headroom for a 9,000-12,000 BTU mini-split’s running load — but its capacity covers roughly two hours of continuous compressor runtime before it needs recharging, and a mini-split cycling on and off in mild weather stretches that further.

The Apex 300 Versatile Power Station (2,765 Wh; $1,699, maker list price, October 2026) rates its inverter to 3,840W, which gives more output margin for an 18,000 BTU unit (Mitsubishi lists a 2,455W maximum heating input for its MUZ-GL18NA), at a higher cost per watt-hour than most mid-range units — our power station price index tracks that $/Wh figure across the models we cover, and it is worth checking before buying a unit for this specific job. Compare options on the power station finder rather than guessing from the wattage numbers alone, since AC output rating and battery capacity both matter and neither alone tells you whether a given unit will run your mini-split.

A whole-home ducted system, with its 3,000W to 5,000W running load before the aux strips even factor in, is at the very top of what a portable power station can do. A few large units are rated for that much output — Jackery lists 7,200W at 120/240V for the Explorer 5000 Plus, and Anker lists 6,000W for the SOLIX F3800 — but capacity is the limit: 85% of the Explorer 5000 Plus’s 5,040 Wh covers roughly 50 to 85 minutes at 3,000W to 5,000W, and a fixed-speed compressor’s startup surge still has to fit within the unit’s surge rating. If backup heat for an outage is the actual goal rather than running the existing heat pump off-grid, a stationary home battery sized and installed for the job is the realistic answer; we cover that sizing question on our home battery backup page. It is a similar gap to the one covered in our portable power station for a gas furnace piece, where the furnace’s own electrical load is modest — blower motor and controls only — but a ducted heat pump’s is not; the two get confused because both heat the same kind of home.

Where a heat pump fits on a wattage chart

Against the rest of a house’s electrical load, even a small mini-split sits in the same range as a window air conditioner or a space heater, while a whole-home system sits closer to an electric dryer or range. Our appliance wattage chart lines all of these up together, which is the fastest way to see where a heat pump’s draw actually falls relative to everything else already pulling from the same panel.