How Much Does a Heat Pump Cost to Run Per Month?

This guide is about what a heat pump costs to run, month by month. It is not about what one costs to buy — we cover purchase and installation separately in our 2026 heat pump cost guide, and you can rough out an installed price with the heat pump cost calculator.

Running cost is where most of the confusion lives. People hear “a heat pump is 300% efficient” and expect their bill to fall by two thirds. Then January arrives, the outdoor temperature drops below the unit’s balance point, the backup resistance heat starts running, and the bill goes the other way. Both things are true at once, and the difference between them is worth several hundred dollars a season.

So here is the honest version: the maths, the worked example, a monthly estimate table you can find your house in, a fuel-by-fuel comparison at stated prices, and the handful of levers that genuinely move the number.

The formula, written out

There is one equation underneath every heat pump running-cost estimate you will ever read. It looks like this:

The 3,412 is not arbitrary. One kilowatt-hour of electricity contains 3,412 BTU of energy. That is a physical constant, not an efficiency rating. It is the conversion that lets you move between the unit heating equipment is sold in (BTU per hour) and the unit your utility bills in (kilowatt-hours).

The COP — coefficient of performance — is the multiplier that makes a heat pump interesting. A COP of 3.0 means the unit delivers three units of heat for every one unit of electricity it draws. It is not creating energy; it is moving heat that already exists in the outdoor air into your house, and moving is far cheaper than making. Electric baseboard heat has a COP of exactly 1.0. That is the whole story of why heat pumps exist.

The word that does the heavy lifting is seasonal. A single COP figure from a spec sheet is measured at one outdoor temperature, usually 47°F. Your winter is not 47°F all the way through. What you want in this formula is a seasonal average COP that reflects your actual climate, which is a lower and less flattering number than the one on the brochure.

The last input, your electricity rate, is the one people most often get wrong. Do not use the “energy charge” line alone. Take the total dollar amount of a recent bill and divide it by the kilowatt-hours used on that same bill. That all-in figure includes delivery, transmission, riders and taxes, and it is frequently 30% to 60% higher than the headline supply rate. It is the number your money actually leaves at.

A worked example, start to finish

Take a 2,000 square foot house in a moderate climate — think Kansas City, Nashville, southern Ohio, roughly IECC climate zone 4. Reasonably insulated, built in the 1990s, now heated by a modern variable-speed air-source heat pump.

Input 1: the annual heating load. For a home like this, the heat that actually has to be delivered over a heating season commonly lands around 50 million BTU. That number comes from a Manual J load calculation combined with local heating degree days — the same arithmetic behind our heat pump sizing guide. If you have had a load calculation done, use its numbers. If you have not, an estimate is fine for this purpose.

Input 2: convert to kWh of heat. 50,000,000 ÷ 3,412 = 14,654 kWh of heat that has to end up inside the house over the season.

Input 3: divide by the seasonal COP. In a zone 4 climate, a good modern inverter heat pump plausibly averages a seasonal COP around 3.0 once you account for cold days, defrost cycles and a little backup heat. So 14,654 ÷ 3.0 = 4,885 kWh of electricity for the season.

Input 4: multiply by the rate. At 18 cents per kWh, 4,885 × $0.18 = about $880 for the heating season.

Now spread that over the calendar, because this is where the monthly number comes from. Heating load is not distributed evenly. In a zone 4 winter, October and April are small, and January alone typically accounts for something like 20% to 28% of the whole season. Take 25% of 4,885 kWh and you get roughly 1,220 kWh in January, or about $220 for that one month, against maybe $60 in October.

That gap is normal and it is not a fault. It is also why an annual average monthly figure is close to useless when you are trying to predict whether you can afford February.

An annual average tells you what you will spend. The January number tells you whether you will panic.

— why we quote peak-month costs, not averages

Why COP and HSPF2 beat SEER2 for winter bills

Every heat pump carries three efficiency ratings, and homeowners routinely shop on the wrong one. Here is what each actually predicts, and we go deeper on all three in SEER2, HSPF2 and COP explained.

SEER2 is a cooling number. It describes how efficiently the unit runs air conditioning across a cooling season. A 20 SEER2 unit will have a lower summer bill than a 15 SEER2 unit. It tells you almost nothing about January. Manufacturers lead with it because it is the biggest, most impressive-looking figure on the label, and because for decades the industry sold cooling first.

HSPF2 is the heating equivalent — a seasonal heating efficiency rating in BTU of heat delivered per watt-hour of electricity consumed. This is the number that predicts your winter bill. It bakes in cold-weather derating, defrost cycles and, importantly, an allowance for backup resistance heat. Current residential ducted equipment generally sits somewhere between about 7.5 and 10+ HSPF2, with ductless mini-splits often rated higher.

COP is an instantaneous measurement at one specific outdoor temperature. It is the most useful number of the three if you can find a full table of it, because it shows you the shape of the performance curve rather than a single blended average.

There is a simple conversion that makes HSPF2 usable in the formula above:

One important caveat. HSPF2 is measured against a standard regional climate profile, not yours. If you live somewhere much colder than the test region, your real-world seasonal COP will come in below what HSPF2 implies. If you live somewhere much milder, it can come in above. For cold-climate buyers, the more useful data is the manufacturer’s rated capacity and COP at 17°F and 5°F, which is the basis of our cold-climate heat pump roundup.

What happens to cost as it gets colder

A heat pump gets worse at its job as the outdoor temperature falls, and it does so in two ways at once. It delivers less heat, and it uses more electricity per unit of heat delivered. Meanwhile, your house needs more heat. Three curves moving the wrong way together.

The table below shows the general shape for a modern cold-climate inverter unit, using manufacturer-rated performance as the reference. Treat these as illustrative ranges, not a spec for any one model — every unit has its own curve, and published data varies widely by brand and capacity.

Read the last two rows together, because that comparison is the single most useful thing on this page. Even at minus 5°F, a working heat pump is still delivering heat for roughly a third less than electric resistance strips. The problem is never that a heat pump becomes worse than baseboard heat. The problem is when the heat pump stops carrying the load and the strips take over.

There is also a defrost penalty that does not show up in a simple COP number. When outdoor humidity and temperature line up in the roughly 25°F to 40°F band, frost builds on the outdoor coil and the unit periodically reverses to melt it, often firing backup heat to keep supply air from going cold. Those cycles are normal — we cover what is normal and what is not in why heat pumps ice up — but they cost real energy, and they are a big reason seasonal COP undershoots spec-sheet COP.

Auxiliary heat: the shocking-January-bill machine

If you get one thing from this guide, get this one. Almost every horror story about a heat pump bill — the $600 January, the “it tripled overnight” post — traces back to auxiliary electric resistance heat running far more than it should.

Auxiliary heat is a bank of electric resistance elements, typically somewhere between 5 and 20 kilowatts, sitting in the air handler. They exist as backup for the coldest hours of the year and for defrost cycles. Their COP is 1.0. Running a 15 kW strip for one hour costs 15 kWh, or $2.70 at 18 cents. Run it eight hours a day for a week and you have added roughly $150 to the month without touching the thermostat again.

Here is the thing that catches people out: auxiliary heat is triggered by control logic, not by physics. The compressor did not fail. The thermostat simply decided the room was too far below setpoint and closed the gap the fast, expensive way. Common triggers include:

1. A deep overnight setback

   Drop the house 8°F at night and the morning recovery is a wide gap. Most thermostats bring on aux once indoor temperature is roughly 2°F below setpoint. You saved a little overnight and handed it all back at 6 a.m. Our thermostat settings guide covers the safe setback range.

2. No outdoor aux lockout configured

   Many thermostats can be told “never use strips above 35°F.” If nobody set that, the strips are free to run on a 45°F day when the compressor could easily have handled it alone.

3. Emergency heat left switched on

   Emergency heat locks out the compressor entirely and runs on strips alone. People flip it on during a cold snap and forget. See emergency heat versus auxiliary heat.

4. An undersized or badly matched system

   If the heat pump cannot carry the load at 30°F, aux is not a backup — it is a co-heater running most of the winter. This is a design problem, not a settings problem.

5. A dirty filter or blocked coil

   Restricted airflow reduces delivered capacity, which widens the gap, which calls aux. A $15 filter can be worth $100 a month.

The fix is usually free. Flatten the thermostat schedule, enable adaptive or smart recovery so the system starts climbing early at low speed, and set an outdoor lockout temperature for aux. On a lot of homes, those three changes alone are worth $50 to $150 in a cold month.

Monthly cost estimates by home size and climate

This is the table people come here for, so read the caveats first. These figures are estimates for the coldest month of the year — think January — covering heating only. They assume an electricity rate of 18 cents per kWh all-in, a reasonably insulated home, correct sizing, and a system that is not leaning on auxiliary heat. They do not include hot water, cooking, lighting or the utility’s fixed monthly charge.

Two adjustments worth making before you use a row. First, scale for your rate: if you pay 12 cents, multiply by 0.67; if you pay 30 cents, multiply by 1.67. Second, scale for your house: a 1970s home with single-pane windows and an uninsulated attic can easily use 50% to 80% more than these figures, while a well-air-sealed home with good windows can come in 20% to 30% under them. Square footage is a proxy for heating load, and a rough one.

If your actual bill is more than about 40% above the relevant range and your rate is close to 18 cents, that is a signal worth chasing. Start with the aux indicator, then the filter, then whether the system is short cycling. If it is running constantly and never reaching setpoint, that is a different problem — see heat pump not heating.

Against gas, propane, oil and resistance heat

The only fair way to compare heating fuels is cost to deliver a fixed amount of usable heat. The table below prices one million BTU of heat actually delivered into the house, after equipment efficiency. Every price in it is a stated assumption, not a promise.

The assumed prices: electricity at 18¢/kWh, which is close to the current US residential average; natural gas at $1.50 per therm, which is roughly where the EIA’s residential series has been running when converted from dollars per thousand cubic feet; propane at $2.50 per gallon; heating oil at $3.50 per gallon. Fuel prices swing hard by region and by season, so substitute your own.

Now the honest part, and it is the part most heat pump articles skip.

Where a heat pump wins on running cost, it usually wins big. Replacing electric baseboard or an electric furnace typically cuts heating electricity by 50% to 65%, and that is the clearest financial case in the whole category. Replacing propane or oil is also a strong case at the prices above — roughly 30% to 45% lower running cost even at a modest seasonal COP. Replacing cheap natural gas is a coin flip that depends heavily on your local gas and electricity prices.

One structural point in favor of the heat pump that the table cannot show: it also does your cooling. If you were going to replace an aging air conditioner anyway, the heat pump absorbs that cost and that equipment. A furnace does not.

Your electricity rate matters more than your equipment

Upgrading from a mid-tier heat pump to a top-tier one might improve seasonal COP from 2.7 to 3.2 — call it a 15% cut in heating electricity. Moving from Massachusetts to Tennessee would cut your rate by more than half. Geography beats equipment, and there is nothing you can do about geography.

US residential electricity prices in 2026 span an enormous range. National average figures sit somewhere around 18 cents per kWh, but the lowest states are in the low-13-cent range and Hawaii runs well over 50 cents, with several New England states and California toward the upper end. Here is the same worked example from earlier — 4,885 kWh of heating electricity for the season — priced at different rates.

Two practical implications. If you are in a low-rate state with expensive delivered fuel — propane country, much of rural America — a heat pump is close to a slam dunk on running cost. If you are in a high-rate state with cheap piped natural gas, run the numbers carefully and consider whether a dual-fuel setup, where a heat pump handles mild weather and a gas furnace takes over below a set outdoor temperature, gives you the better of both.

The other thing worth knowing: in many places, electricity rates have been rising faster than gas rates recently, and utilities are increasingly shifting costs into fixed monthly charges. Both of those move the break-even point. Check what your utility has filed, not what was true three years ago.

Time-of-use tariffs and what they change

Time-of-use pricing charges different rates at different hours. A common shape is a cheap overnight and midday period, a much more expensive block in the late afternoon and evening, and sometimes a distinct winter morning peak from roughly 6 to 9 a.m. Spreads vary, but a peak rate two to three times the off-peak rate is not unusual, and in some markets it is wider.

For a heat pump this cuts both ways. The bad news is that winter heating demand naturally peaks in the early morning and again in the evening, which in many tariffs is precisely when electricity is most expensive. Left alone, a heat pump concentrates its consumption in the worst hours.

The good news is that a house has thermal mass, and you can use it. The strategy is pre-heating: let the system warm the house by an extra degree or two during the cheap window immediately before the peak, then coast. The house drifts down slowly through the expensive hours instead of calling for heat during them.

A few practical notes. Most modern smart thermostats can run a time-of-use schedule, and some integrate directly with utility rate plans. Well-insulated, tight homes hold a pre-heat far better than leaky ones, so the strategy is worth more the better your envelope is. And before you enroll in a TOU plan, pull twelve months of hourly usage data from your utility if they offer it — many do — and check what your bill would have been. Some households genuinely lose money on TOU.

Time-of-use rates also change the arithmetic if you have or are considering rooftop solar, because generation lands in the middle of the day. We work through that pairing in detail in pairing a heat pump with solar panels.

The levers that actually lower the bill

Ranked roughly by how much they move the number, for the least money.

1. Stop the auxiliary heat from running unnecessarily

   Free, and the biggest single lever in most homes. Flatten the schedule, cap setbacks at 2 to 4°F, turn on adaptive recovery, and configure an outdoor lockout so the strips cannot run above a set temperature. Confirm emergency heat is off.

2. Hold a steady setpoint

   Also free. Heat pumps are most efficient running long and slow at low compressor speed. Pick a temperature you are comfortable at, hold it, and accept that the furnace playbook does not transfer.

3. Change the filter on schedule

   A few dollars a quarter. Restricted airflow drops delivered capacity, lengthens run times and invites aux heat. Every one to three months for a 1-inch filter, depending on pets and dust. This and the rest of the routine live in our maintenance checklist.

4. Air-seal the obvious leaks

   A weekend and under $100 of caulk, foam and weatherstripping. Attic hatches, rim joists, plumbing and wiring penetrations, and around window and door frames. Reducing the heating load reduces every future bill, permanently, regardless of what equipment you own.

5. Insulate the attic

   Bigger money, but the highest-return envelope upgrade in most US homes, and many utilities subsidize it. An underinsulated attic is why some houses use 60% more than the table above predicts.

6. Keep the outdoor unit clear

   Free. Leaves, grass clippings, snow drifts and shrubs choke airflow across the outdoor coil, which cuts capacity and triggers extra defrost cycles. Give it two feet of clearance and clear snow away from the base after storms.

7. Look at your rate plan

   Free to check. A heating-season rate, an electrification tariff or a time-of-use plan that suits your pattern can be worth more than any equipment upgrade.

8. Get the system commissioned properly

   Costs a service call. Refrigerant charge, airflow, and aux staging set correctly at install can be worth 10% to 20% of heating energy. Refrigerant work requires an EPA-certified technician, and 2025-onward equipment uses A2L refrigerants like R-454B or R-32 that need rated tools and training. This is not a DIY area.

6 mistakes that inflate running cost

Frequently asked questions

Your running-cost checklist