Almost every homeowner asking this question wants one number: which one is cheaper. The honest answer is that it depends on three things you can actually check, and none of them are the brand on the box.
The difference that drives everything else
A gas furnace makes heat. It burns fuel and converts it, and the very best ones convert around 95 to 98 percent of what they burn into heat in your house.
A heat pump does not make heat. It moves it — pulling warmth out of the outside air and delivering it inside, the same way a refrigerator moves heat out of the box. Because moving is cheaper than making, a heat pump can deliver more heat energy than the electrical energy it consumes.
That is the whole reason the running cost conversation exists, and it is why the comparison is not simply "gas is cheap".
What actually decides your monthly cost
Your electric rate
This is the single biggest variable, and it is the one people skip. Rates in this region vary meaningfully depending on which utility serves you, and a heat pump's operating cost tracks that rate directly.
Find your rate per kilowatt-hour on your bill before you let anyone quote you a monthly saving. A contractor who tells you what you will save without asking who your utility is has not done the math.
How cold it actually gets, and for how long
A heat pump is most efficient in mild cold. Around here that is most of the winter. During a genuine cold snap efficiency drops and the backup heat source does more of the work, which costs more.
The useful question is not "what happens at 20 degrees" but "how many days a year does it actually sit at 20 degrees here". For most of the Puget Sound area, not many.
How well the house holds heat
An efficient system in a leaky house still pays to heat the outdoors. If you have single-pane windows, no attic insulation or ducts running through an unconditioned crawlspace, that is where the money is going, and no equipment swap fixes it.
Where a heat pump clearly wins
- You want air conditioning too. This is the strongest case by far. A heat pump is a single system that heats and cools. Buying a furnace and a separate AC means two pieces of equipment, two installations, and two things to replace later.
- You are replacing an aging furnace anyway. If the decision is already "spend money on heating equipment", the incremental case for a heat pump is much stronger than replacing a furnace that has years left.
- You currently heat with electric resistance. Baseboards or electric furnaces are the most expensive way to heat a house. A heat pump against electric resistance is not a close call.
Where a furnace still makes sense
- Your furnace is young and working. Replacing functioning equipment rarely pays back.
- You need a lot of heat very fast. Furnaces deliver hotter air. Some people simply prefer how that feels.
- The electrical service will not support it. Some older homes need a panel upgrade first, which is a real cost that belongs in the comparison.
What to do before you decide
- Find your electric rate per kWh on a recent bill.
- Find what you spent on gas last winter, not last month.
- Ask whether your electrical panel supports a heat pump, and what it costs if it does not.
- Ask what the backup heat source would be and when it takes over.
- Ask what rebates you actually qualify for, and confirm they apply to your utility.
Rebates in particular follow the meter, not the county. Two neighbors on different utilities can qualify for different amounts, so anything you read online about "Washington rebates" needs checking against your own bill.
Getting a number for your house
Both of these are good systems. The right one depends on your rate, your house and what you are trying to fix — and the difference between a good install and a bad one matters more than the difference between the two technologies.
If you want the comparison run against your actual bills and your actual house, get a free estimate and we will size both options and show you the math rather than a brochure figure.