About the Heat Pump vs Furnace Calculator
This heat pump vs furnace calculator compares what it costs to heat the same home with an electric air-source heat pump and with a natural gas furnace. Enter your yearly heating load, local gas and electricity prices, the furnace efficiency (AFUE) and the heat pump’s seasonal efficiency (COP), plus the installed prices and any rebates.
It is built for homeowners replacing an old furnace or central air conditioner who want to know whether a heat pump will save money, and how long the extra upfront cost takes to pay back. The chart shows cumulative cost of each option over the years you plan to stay.
Because a heat pump also cools, you can enter the cost of an air conditioner you would otherwise need to buy. The comparison covers heating only; it does not include cooling savings, maintenance or future price changes, and seasonal COP falls in very cold climates, so use a conservative figure if you live somewhere with long sub-freezing spells. The default prices are close to the 2025 US residential averages from the EIA: 17.3¢ per kWh for electricity and $15.34 per thousand cubic feet for natural gas, about $1.48 per therm. Replace them with the rates on your own bills, because local prices vary widely.
With the default inputs, the annual savings with heat pump is $13.20. Change any value above to recalculate instantly.
How to use the heat pump vs furnace calculator
- 1Estimate your yearly heating load — from past gas bills, therms × AFUE ÷ 10.
- 2Enter your gas price per therm and electricity price per kWh from recent bills.
- 3Enter the furnace AFUE and a realistic seasonal COP for the heat pump.
- 4Add installed prices, rebates and any air conditioner you would avoid buying.
- 5Compare annual costs, payback and the cumulative cost chart.
Formula and method
The heating load is the heat your home needs over a season, in million BTU. One therm of gas is 100,000 BTU, so a furnace needs Load × 10 ÷ AFUE therms to deliver it. One kWh of electricity is 3,412 BTU, and a heat pump moves COP units of heat for every unit of electricity, so it needs Load × 1,000,000 ÷ 3,412 ÷ COP kWh.
Annual savings are the furnace cost minus the heat pump cost. The extra upfront cost is the heat pump price minus rebates, minus the furnace price and any AC you avoid buying; payback is that extra cost divided by the annual savings. The break-even COP is the seasonal efficiency at which both systems cost the same to run.
- Load
- Annual heat delivered to the home, million BTU
- AFUE
- Annual fuel utilization efficiency of the furnace (e.g. 0.95)
- COP
- Seasonal coefficient of performance of the heat pump
- 3,412
- BTU in one kilowatt-hour
Worked examples
Typical home at US-average energy prices
Delivering 60 million BTU takes 631.6 therms in a 95% furnace ($947.37 at $1.50) or 5,495 kWh in a COP 3.2 heat pump ($934.16 at $0.17). At near-average US prices the two cost almost the same to run: the heat pump saves only $13.20 a year. The break-even COP is 3.16, just below 3.2. With $5,500 more upfront, the savings would take over 400 years to repay it, so over 15 years the heat pump is $5,302 behind. It pays off only with cheaper electricity, a higher COP or an avoided AC purchase.
Replacing both furnace and AC with cheap electricity
With gas at $2.00 a therm and power at $0.12 per kWh, the furnace costs $1,263 a year and the heat pump $703. Because the heat pump also replaces a $5,000 air conditioner, it costs only $500 more upfront and pays back in under a year, saving about $7,900 over 15 years.
Cheap gas, expensive electricity, cold climate
An 80 million BTU load costs $917 with gas at $1.10, but a heat pump averaging COP 2.5 on $0.22 electricity costs $2,063. It would need a seasonal COP of about 5.6 to match gas, so here the furnace is the cheaper option to run.
Frequently asked questions
Is a heat pump cheaper to run than a gas furnace?+
It depends on the price ratio. A heat pump with a seasonal COP of 3 turns one kWh into about 10,200 BTU of heat. So if a kWh of electricity costs less than about three times what 3,412 BTU of delivered gas heat costs (gas price per kWh ÷ AFUE), the heat pump is cheaper to run.
What COP should I use for a heat pump?+
Seasonal COP for modern air-source heat pumps is usually 2.5–3.5 across a whole winter, higher in mild climates and lower where temperatures often drop below freezing. Ground-source (geothermal) systems commonly reach 3.5–4.5.
How do I find my annual heating load?+
Add up the therms on last winter’s gas bills (excluding water heating and cooking, roughly the summer baseline), multiply by your furnace AFUE and divide by 10. For example 700 therms × 0.9 ÷ 10 = 63 million BTU.
Do heat pumps work in cold climates?+
Yes. Cold-climate heat pumps keep working well below 0 °F, though efficiency drops as it gets colder. Many homes in very cold regions keep a backup furnace or electric strips for the coldest days, which lowers the seasonal COP.
Is there still a federal tax credit for heat pumps?+
The federal Energy Efficient Home Improvement Credit (Section 25C), which paid 30% up to $2,000 for qualifying heat pumps, was ended by the 2025 One Big Beautiful Bill Act for equipment placed in service after December 31, 2025. State, utility and local rebates may still apply, so enter only the incentives you can confirm.
Should I include air conditioning in the comparison?+
If you would need to replace a central air conditioner anyway, include its cost in "AC cost avoided", because a heat pump provides both heating and cooling. That often turns a long payback into an immediate one.
Results are estimates for educational purposes and are not financial advice. Rates, fees and terms vary — confirm with your lender or a licensed advisor before making decisions.