Ask ten contractors what a heat pump costs to run per month and you will get ten confident numbers, all of them made up. We are not going to do that. Instead, here is the arithmetic we walk homeowners through in Federal Way, Kent, Puyallup and Olympia, using numbers that are already printed on your own power bill.
The short answer nobody likes to give
A heat pump's monthly running cost is three numbers multiplied together:
- How much heat your house loses on a given month's weather.
- How efficiently your equipment replaces that heat.
- What your utility charges per kilowatt-hour.
Change any one of those and the answer changes. A 1,400 square foot 1978 rambler with original insulation and a 3,200 square foot 2015 build with a tight envelope can have the same ducted heat pump installed and end up hundreds of dollars apart over a winter. That is why the honest answer is a method, not a figure.
The three numbers, explained
1. Heat loss — how leaky your house is
Every hour your house loses heat to the outdoors, and the colder it is outside, the faster it leaks. That is what a Manual J load calculation measures, and it is run against your city's winter design temperature. In our service area those range from 17°F in Olympia, Lacey, Tumwater, DuPont and Yelm to 29°F in Tacoma, Lakewood, Gig Harbor and Port Orchard — a twelve-degree spread across a 60-mile drive.
Insulation, window quality, air sealing, ceiling height and how many exterior walls a room has matter more than square footage alone. This is also why the cheapest thing you can do for your monthly bill often is not HVAC at all — it is attic insulation and air sealing.
2. Efficiency — the reason heat pumps are worth the money
An electric baseboard heater or a furnace heat strip converts one unit of electricity into exactly one unit of heat. That is a coefficient of performance of 1.0, and it is the ceiling for resistance heat.
A heat pump does not make heat. It moves heat from outdoor air into your house, which is why it can deliver more energy than it consumes. In the 35°F to 50°F range where the overwhelming majority of Puget Sound winter hours sit, a modern heat pump typically returns two to three-plus units of heat per unit of electricity. That multiplier is the entire reason a heat pump beats electric resistance heat by roughly 30 to 50 percent on heating cost.
Efficiency ratings on the equipment — HSPF2 for heating, SEER2 for cooling — are the shorthand for this. Higher numbers cost more up front and consume less per hour. Whether that trade pays off depends on how many hours you run it.
3. Your rate — and it is not the same across our service area
Pull out your power bill and find your cents-per-kilowatt-hour. Rates change, tiers exist, and the utility depends entirely on your address, not your county. Most of our service area is on one big regional utility. Tacoma, Fife, Fircrest and University Place are Tacoma Power. Seattle is City Light. Gig Harbor and Fox Island are Peninsula Light. Parkland and Spanaway are member-owned mutuals. Burien, Normandy Park, Renton, SeaTac and Tukwila are split depending on the address.
Washington has some of the cheapest electricity in the country thanks to hydropower, which is exactly why electric heat pumps pencil out well here.
Run the math on your own bill in five minutes
You do not need a spreadsheet. You need two bills.
- Find a shoulder-season month — May or September, when you were neither heating nor cooling. That kilowatt-hour total is your household baseline: lights, fridge, laundry, water heater, everything that is not HVAC.
- Find a real winter month — December or January.
- Subtract. Winter kWh minus baseline kWh is approximately your heating consumption for that month.
- Multiply by your rate. That is roughly what heating cost you.
If you currently heat with electric baseboard, wall heaters or a furnace with electric strips, that heating number is the one a heat pump attacks. Cutting it 30 to 50 percent is the realistic expectation with correctly sized equipment.
| What you have now | What changes with a heat pump |
|---|---|
| What you have nowElectric baseboard or wall heaters | What changes with a heat pumpHeating consumption typically drops 30–50%, and you gain cooling |
| What you have nowElectric furnace with heat strips | What changes with a heat pumpSimilar drop; strips become backup only, not primary heat |
| What you have nowGas furnace | What changes with a heat pumpGas bill shrinks or disappears, electric bill rises — compare total energy spend |
| What you have nowOlder heat pump (15+ years, R-22) | What changes with a heat pumpModest improvement from better efficiency ratings and a working refrigerant charge |
Why your neighbor's number is not your number
We hear this constantly: my neighbor has the same house and pays less. Usually one of these is the reason.
- Thermostat setpoint. The difference between 68°F and 72°F is not small. Every degree costs.
- Occupancy. A retired couple home all day heats more hours than a household that leaves at 7 a.m.
- Duct condition. Leaky crawlspace ducts dump conditioned air under the house. You pay for heat that never reaches a room.
- Backup heat running when it shouldn't. This is the single most common cause of a shocking bill. If the thermostat is left on EM HEAT, or the balance point is set wrong, you are paying resistance-heat prices with a heat pump sitting outside doing nothing.
- Equipment tier. A variable-speed system modulates and runs long, low-output cycles. A single-stage unit is on at 100 percent or off. Both heat the house; they do not consume the same way.
What actually moves the monthly number
Sizing
Oversized equipment short-cycles, wears out early and does not save money. Undersized equipment leans on backup heat during cold snaps, which is the expensive kind of heat. A real load calculation is the cheapest efficiency upgrade available, and it comes standard with every estimate we write.
Filters and airflow
A clogged filter makes the blower work harder and the system run longer. Change it on schedule. This is free money.
Ductwork
If the ducts under your house are crushed, disconnected or uninsulated, a new heat pump inherits that loss. We would rather tell you that during the estimate than after.
Thermostat habits
Heat pumps prefer steady. Modest setbacks of two to four degrees are fine. Deep setbacks force a hard recovery, and hard recoveries call the heat strips.
Summer is the cheap half
Puget Sound's cooling season is short. The same outdoor unit that carries you through January runs comparatively few hours in July and August, so for most homes here cooling is the smaller share of the annual bill by a wide margin. That matters when you compare a heat pump against a furnace-plus-AC pairing — you are buying two seasons of use from one machine.
If you are weighing fuels rather than just running cost, our heat pump versus gas furnace breakdown walks the full comparison including install price.
Where rebates fit into the monthly math
Rebates do not lower your bill — they lower what you paid to get the equipment, which shortens the time the monthly savings take to matter. Local utility rebate money is available toward a qualifying heat pump when it replaces an existing electric or fossil-fuel system; the amount depends on the system you are replacing and the equipment you install. Programs change, so we confirm your current eligibility and handle the paperwork. Note two things: the federal 25C tax credit ended December 31, 2025, and utility rebate programs pay only through their own contractor networks, with rules that move around, so we check the current requirements before we quote. Details are in our local utility rebate guide.
And if your address is on Tacoma Power, Seattle City Light or Peninsula Light, the big regional program does not apply to you — your utility has its own. We check the meter, not the zip code.
Get a number that reflects your actual house
We will run the load calculation, look at your ducts, ask what you set the thermostat to, and tell you what we honestly expect. If your existing system is young and healthy and the savings do not justify the spend yet, we will say that too.
Request a free in-home estimate or call (253) 785-4622, Monday through Friday, 8 to 6. Every installation carries a 10-year parts and labor warranty, and most are finished in one day.