Heat Pump vs Furnace Calculator
Compare a heat pump against your current furnace on running cost, carbon and payback
Your current heating
From your utility bill’s twelve-month summary.
Printed on the furnace label. Older units 78-80%, condensing 90-98%.
EIA annual average (verified 2026-08-16). Propane and oil are 2025-26 heating season figures.
Leave at 0 if you have no air conditioning.
The heat pump
Federal minimum is 7.4. Better units reach 9-11.
Runs at a COP of 1.0. The biggest lever in cold climates.
US residential average, EIA (verified 2026-08-16).
Only the difference between the two matters for payback.
The federal 25C credit ended for systems placed in service after Dec 31, 2025. State and utility programs may still apply.
The two answers
Cost and carbon often disagree, so they are reported separately rather than blended into a single verdict.
Where your crossover sits
Annual running cost
Annual carbon
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Reading the result honestly
Most heat pump calculators are published by companies that sell heat pumps, and they tend to return a saving. At 2026 US average energy prices, a mainstream ducted heat pump replacing an 80% AFUE gas furnace usually does not save money on running cost. It is close, and it moves with your local prices, but the honest default answer is that gas is still slightly cheaper per unit of delivered heat.
That is not the whole picture. A heat pump replaces your air conditioner at the same time, so the cooling side usually improves. It cuts carbon substantially on most grids. And the economics swing hard on three things: your electricity price, your gas price, and the efficiency of the unit you actually buy.
The break-even HSPF2 figure above is the number worth taking away. It tells you what rating a heat pump would need for the running cost to come out in your favour at your own prices — which is a far more useful thing to know when you are standing in front of two quotes than a single yes or no.
How the comparison is made
Both systems are compared on delivered heat, not fuel burned. Your fuel use times its energy content times your AFUE gives the heat that actually reaches the house; the heat pump then has to supply that same amount. Its electricity is that heat divided by the seasonal COP, except for the share met by resistance backup, which runs at a COP of 1.0.
Where the numbers come from
- Fuel carbon: EPA GHG Emission Factors Hub 2025 — natural gas 5.306 kg CO2/therm, propane 5.72 kg/gal, heating oil 10.21 kg/gal.
- Grid carbon: EPA eGRID2023 Revision 2, by subregion.
- Energy prices: EIA. Natural gas uses the annual average rather than a recent month, because monthly per-Mcf prices spike every summer when fixed charges spread across low volumes. Propane and heating oil are 2025-26 heating season figures — EIA only collects them October to March.
- HSPF2 to COP: divide by 3.412 to convert BTU per watt-hour into a dimensionless ratio.
How to Use This Calculator
- Enter your current heating fuel and how much you use. Take the annual total from your utility bills - therms for natural gas, gallons for propane or heating oil. Most utilities show a twelve-month summary.
- Set your current system efficiency. AFUE is printed on the furnace label. Older units run 78-80%, modern condensing furnaces 90-98%. Electric resistance heating is 100% by definition.
- Enter the heat pump rating. HSPF2 is the seasonal heating efficiency. Current federal minimum is 7.4 for split systems; better units reach 9-11. Divide by 3.412 to get the seasonal COP.
- Set the backup share. The percentage of your heating load met by electric resistance strips when it is too cold for the heat pump. This runs at a COP of 1.0 and is the single biggest lever on cold-climate economics.
- Compare both answers. You get the annual cost change and the annual carbon change separately, because they often disagree. The break-even HSPF2 tells you what rating a unit would need for the running cost to work out in your favour at your prices.
Frequently Asked Questions
Will a heat pump save me money over a gas furnace?
Often not on running cost alone, at 2026 prices. With US average electricity at 18.4 cents per kilowatt hour and natural gas at about $1.48 a therm, an 80% AFUE furnace delivers heat at roughly $18.50 per million BTU while a heat pump with a seasonal COP of 2.64 delivers it at about $20.50. It flips in your favour if your electricity is cheaper, your gas is dearer, or the heat pump is rated HSPF2 10 or better. This calculator tells you exactly where your own crossover sits.
What does HSPF2 mean and how does it convert to COP?
HSPF2 is the seasonal heating output in BTU divided by the electricity consumed in watt hours, averaged across a whole heating season. Divide by 3.412 to get a dimensionless coefficient of performance: HSPF2 9.0 is a COP of 2.64, meaning the unit moves 2.64 units of heat for every unit of electricity it consumes. The current federal minimum is HSPF2 7.4 for split systems.
Do heat pumps work in cold climates?
Modern cold-climate models do. To carry ENERGY STAR's Cold Climate designation a unit must hold a COP of at least 1.75 at 5F while still delivering 70% of its rated capacity, so it stays more efficient than resistance heat well below freezing. What actually matters for your bill is how much of the season falls back to the electric resistance strips, which run at a COP of 1.0. That is the backup share field, and it is the biggest single lever in the whole calculation.
Does a heat pump always cut emissions?
No, and that surprises people. On the US average grid, replacing a gas furnace with an HSPF2 9.0 heat pump cuts heating and cooling emissions by roughly a third. On a clean grid like upstate New York, at 0.109 kg CO2 per kilowatt hour, the cut is over 75%. But on a coal-heavy grid such as Wisconsin's, at 0.636 kg per kilowatt hour, the swap can actually increase emissions. Set your grid region above and the calculator will tell you which case you are in.
Is there still a federal tax credit for heat pumps?
No. The Section 25C Energy Efficient Home Improvement Credit, worth up to $2,000 for a qualifying heat pump, was terminated by the One Big Beautiful Bill Act for property placed in service after December 31, 2025. The IRS uses the placed-in-service date, not the purchase date. State programs, utility rebates and the HEAR and HOMES rebate programs are unaffected and are now the main source of support - enter whatever you qualify for in the rebates field.