Heat pump running cost in Idaho
In Idaho, a heat pump costs about 93% more to run than a 95% AFUE gas furnace. Against propane, heating oil and electric baseboard the answer is different, and all four are below.
Idaho energy prices, 2025-12, 2026-01, 2026-02
The December 2025 to February 2026 EIA heating season mean, pulled . Every figure on this page is in the CSV and JSON download, published under CC BY 4.0.
| Figure | Value | Source |
|---|---|---|
| Residential electricity | $0.122/kWh | EIA, by state |
| Residential natural gas | $0.67/therm | EIA, by state |
| Propane | $2.23/gal | EIA, PADD 4, Rocky Mountain |
| Heating oil | $3.82/gal | EIA, United States average |
| Electricity to gas price ratio | 5.37 to 1 | derived |
| Breakeven ratio for this equipment | 2.78 to 1 | derived |
| Annual heating degree days | 4,832 | EIA, MTN division |
Idaho ranks 42 of 45 states by electricity to gas price ratio, where 1 is most favourable to a heat pump.
Cost to deliver one kWh of heat in Idaho
| Current system | Fuel price | $ per kWh heat | Heat pump verdict | Difference |
|---|---|---|---|---|
| Natural gas furnace | $0.665/therm | 0.0239 | More expensive to run | 93% |
| Propane furnace | $2.23/gallon | 0.0874 | Cheaper to run | 47% |
| Heating oil furnace or boiler | $3.82/gallon | 0.1134 | Cheaper to run | 59% |
| Electric resistance (baseboard or furnace) | $0.122/kWh | 0.1219 | Cheaper to run | 62% |
| Heat pump, COP 2.64 | $0.122/kWh | 0.0462 |
Assumes a cold climate heat pump at HSPF2 11.0 with 10% of heat from electric resistance backup. Propane and heating oil are published by EIA regionally rather than by state, so those are the nearest regional figures. Change any of it on the calculator.
Rough monthly cost in Idaho
| System | Winter month | Per year |
|---|---|---|
| Gas furnace, 95% AFUE | $78 | $487 |
| Heat pump, effective COP 2.64 | $151 | $943 |
An 1,800 sq ft home of typical construction, at 4,832 annual heating degree days for the MTN census division. The square foot coefficient behind this is a rule of thumb rather than a measurement and can be wrong by half in either direction. How this is worked out, and a better method if you have a year of bills.
What this page does not tell you
Running cost only, at state average prices. It excludes equipment and installation cost, rebates, and the fact that a heat pump also replaces an air conditioner. State averages hide large differences between utilities inside Idaho, and this page cannot know your balance point or how much backup heat your system would actually use, which is the input that moves the answer most.
What Idaho households have actually reported
Everything above is a state average price applied to a model house. Below are real Idaho households who published their own winter figures, normalised so they can be compared with each other and with your own bill. There is one so far.
| Household | Floor area | kWh | Wh per sq ft per HDD | Worked through in |
|---|---|---|---|---|
| Idaho mountains, climate zone 6B all heat pumps |
3,850 | not given | cannot compute | the household dataset |
Watt hours per square foot per heating degree day, which is how this site makes houses of different sizes in different climates comparable. Households with no identified fault sit between 0.53 and 0.92. The full dataset, the method behind that figure, and what was wrong in every household above the band.
If your own figure lands well above these, that is worth chasing rather than accepting, because every household in this dataset above the normal band turned out to have a specific and mostly fixable cause. The two cheapest things to rule out are auxiliary heat running when it does not need to and a compressor lockout left at a factory default.
Where to go from here
Because gas wins on running cost in Idaho, the question worth asking is not whether to switch but whether a dual fuel system beats both, which it usually does, and where its crossover temperature belongs.
If you already have a heat pump and the bill is higher than you expected, start with the four things that make a winter bill run high and how to tell which one is yours. If somebody has told you your usage is insane, the questions people actually ask when the bill arrives covers what that comparison is usually missing.
If you are still choosing, the comparison depends on what you are replacing: a gas furnace, propane, heating oil, or electric baseboards, where the heat pump wins by a wide margin in every state including this one.
And if you want to check the arithmetic rather than take it, every constant and limitation is listed, the data is rebuilt from EIA on a documented schedule, and the things this site has got wrong are published rather than quietly edited.
The reasoning behind these numbers
The verdict at the top of this page turns on one threshold, and that threshold is set by your equipment rather than by your climate, which is the single most misunderstood thing about heat pump running cost. The price it is compared against comes from EIA, averaged across December to February, and using any other window inflates the gas price enough to flip the verdict in fifteen states. This site published that mistake before catching it.