Heat pump operating cost in Seattle depends mostly on your electric utility. On City Light’s current Seattle rate of 13.38 cents per kWh, a heat pump costs less to run than a 95% efficient gas furnace whenever its coefficient of performance (COP) is above about 2.2. On PSE’s rate of about 20.6 cents, it needs about 3.4. Backup heat and summer cooling change the final bill.
The Seattle Heat Pump Company plans ducted heat pump projects across Seattle and King County, with installation by licensed and insured contractors, and publishes this math so you can judge the economics before any equipment is chosen. This guide lays out the current rates, the per-unit cost of heat from each fuel, a simple way to estimate your own house, and the things that make real bills differ from the arithmetic.
Key takeaways
- Break-even COP against a 95% gas furnace: about 2.2 on City Light Seattle rates, 2.4 on City Light suburban rates, 3.4 on PSE electric.
- Electric resistance heat costs about three times as much per unit of heat as a heat pump averaging a COP of 3.
- PSE has requested further increases of 17.75% for electricity and 12.93% for gas; they are not approved.
- No official Washington heating oil price series exists, so oil savings cannot be calculated from public data.
The rates that drive the math
Three utilities’ rates cover nearly every house in the Seattle area.
| Utility and area | Energy rate | Fixed charge |
|---|---|---|
| City Light, Seattle | 13.38¢ per kWh | $0.3945 per day |
| City Light, Shoreline, Burien, SeaTac and unincorporated King County | 14.64¢ per kWh | $0.4261 per day |
| City Light, Lake Forest Park | 14.65¢ per kWh | $0.4262 per day |
| City Light, Renton portion | 13.56¢ per kWh | Not listed here |
| PSE electric (Eastside and most suburbs) | about 20.6¢ per kWh | $7.49 per month |
| PSE natural gas (Seattle and most of King County) | about $1.67 per therm | $14.00 per month |
City Light’s rates rose an average of 5.4% on January 1, 2026. PSE’s figures are its residential averages effective May 1, 2026. Inside Seattle, City Light sells the electricity and PSE sells the gas, so a Seattle house compares the first and last rows. On the Eastside, PSE sells both.
What a unit of heat costs from each source
The fairest comparison is the cost of one million BTU of heat actually delivered to the house, using energy charges only. That strips out fixed charges and taxes, which you pay either way if you keep both services.
| Heat source | City Light Seattle | City Light suburban | PSE electric |
|---|---|---|---|
| Heat pump, COP 3 (illustrative) | about $13 | about $14 | about $20 |
| Heat pump, COP 2 (illustrative) | about $20 | about $21 | about $30 |
| Electric resistance, COP 1 | about $39 | about $43 | about $60 |
| Gas furnace, 95% efficient (PSE gas) | about $18 | about $18 | about $18 |
The break-even COPs fall straight out of that table. Divide the cost of resistance heat by the cost of gas heat: $39 divided by $18 gives about 2.2 for City Light Seattle, about 2.4 for City Light suburban, and about 3.4 for PSE. Above those COPs, the heat pump is cheaper per unit of heat. Below them, gas is.
COP is not a fixed property of a heat pump. It is highest in mild weather and falls as the outdoor temperature drops. Seattle spends much of its heating season between about 35°F and 55°F, where a modern variable-speed unit runs efficiently. The SEER2 and HSPF2 guide explains how the seasonal heating rating relates to COP.
Estimating your own house
You can get a reasonable first estimate from last winter’s gas bills, with no special tools.
Take the therms your furnace burned over the heating season. Separate out gas used by a water heater or range if you can; summer bills show roughly what those use each month. Each therm burned in a 95% furnace delivers about 95,000 BTU of heat, which equals about 27.8 kWh of heat. A heat pump averaging a COP of 3 delivers that same heat with about 9.3 kWh of electricity. At City Light’s 13.38 cents, that is about $1.24, compared with about $1.67 for the therm. At PSE’s 20.6 cents, it is about $1.91.
Swap in a lower COP for an older furnace’s efficiency or for a less efficient heat pump, and the answer moves. An 80% furnace delivers less heat per therm, which makes the heat pump look better. A seasonal COP of 2.5 instead of 3 makes it look worse. The point of the exercise is to see which side of the break-even your house sits on, not to predict a bill to the dollar.
The cost estimator runs a version of this for your utility, and the heat pump versus gas furnace guide covers the rest of that decision.
See what your house would cost to heatThe assessment sizes the system and checks the things that decide the bill: ducts, backup heat and controls.
Get an EstimateWhat makes real bills differ from the arithmetic
Backup heat
Every hour electric resistance strips carry the house costs about three times what the same heat costs from a heat pump at a COP of 3. A properly sized system with the backup locked out above Seattle’s code limits uses strips on only a handful of hours. An undersized system, a thermostat left on furnace settings, or deep nighttime setbacks that trigger strips every morning can erase much of the advantage. The backup heat settings guide covers how to set them.
Ducts and airflow
A heat pump that cannot move enough air runs longer, delivers lower COP and calls for backup sooner. Leaky ducts in a crawlspace or attic heat spaces you don’t live in. Those losses show up as electricity use, which is why checking existing ductwork belongs before equipment selection.
Summer cooling
If your house had no air conditioning, a heat pump adds summer electricity use that did not exist before. Sea-Tac’s cooling degree days roughly doubled between the 1990s and the last decade, so that usage is larger than it would have been twenty years ago. Most people who add cooling count it as a comfort purchase rather than a cost, but it belongs in the comparison.
The gas basic charge
If you remove gas entirely, the $14 monthly PSE gas basic charge goes away too. If you keep gas for a range, water heater or fireplace, it stays, and your gas savings are only the therms the furnace used to burn.
The house itself
A leaky older house loses heat faster, so it needs more heat from any source. That raises both the gas bill and the heat pump bill in proportion; it does not by itself make a heat pump a worse choice. One widely shared post claimed that a heat pump might double winter bills in a pre-1980 Seattle house, and commenters disagreed sharply. The comparison per unit of heat in the tables above still applies. What changes in a leaky house is the size of the numbers, which is a reason to consider air sealing alongside the heat pump.
Rates are moving
City Light’s January 2026 increase averaged 5.4%. PSE has filed a multi-year rate plan that requests increases of 17.75% for typical residential electricity and 12.93% for gas in its first year, followed by smaller increases after that. Those are requests to state regulators, not approved rates. If approved as filed, PSE electricity would rise faster than PSE gas, pushing the Eastside break-even COP higher. That is one more reason a dual fuel heat pump remains a common choice in PSE territory, while Seattle’s City Light rates favor all-electric systems.
Oil heat
There is no official weekly heating oil price series for Washington, so any precise oil-versus-heat-pump calculation would rest on a number nobody publishes. Your own delivery receipts from the last two winters are the best baseline. Oil heat also carries the tank: a buried or basement tank is a long-term liability, and Seattle requires a tank out of service for a year or more to be decommissioned. Seattle Clean Heat offers $2,000 off a qualifying conversion. See heat pump versus oil furnace and oil to heat pump conversion.
Help with the bill itself
The City of Seattle’s Utility Discount Program gives income-qualified Seattle residents a 60% discount on City Light electric bills. For a household that qualifies, that discount changes the operating cost comparison substantially in the heat pump’s favor. The Seattle rebate guide covers upfront incentives, and the furnace to heat pump conversion page covers how a gas-to-heat-pump project is planned.