Heat Pump vs Gas Furnace Calculator

The answer depends on three things: your climate, your energy prices, and how long you plan to stay in the home. A heat pump is not universally better or worse than a gas furnace. It is a different technology with different cost characteristics, and the math changes depending on where you live.

Heat pumps move heat instead of generating it. In moderate weather, they deliver 2.5 to 3.5 units of heat for every unit of electricity consumed. That is 250% to 350% efficient compared to a gas furnace at 80% to 96%. But as temperatures drop, a heat pump works harder and its effective COP falls. In very cold climates, the operating cost advantage can shrink or disappear entirely.

This calculator adjusts for that reality using IECC climate zones and COP reduction factors based on NEEP cold-climate heat pump data. It does not assume best-case conditions. It models what you can realistically expect in your state.

COP (Coefficient of Performance) is the efficiency metric that determines whether a heat pump is cheaper to run than a gas furnace. A COP of 3.0 means the heat pump delivers 3 kWh of heat for every 1 kWh of electricity it uses.

At a COP of 3.0, the cost of heat pump heating per therm equivalent is approximately one-third of the electricity rate times 29.3 (the kWh-to-therm conversion). At $0.12/kWh, that works out to about $1.17 per therm equivalent. If natural gas costs $1.10/therm and your furnace is 80% efficient, gas heating costs $1.38 per useful therm. In that case, the heat pump wins by about $0.21 per therm.

But COP drops in cold weather. At 0 degrees F, even a good cold-climate heat pump might deliver a COP of 1.5 to 2.0. At those levels, the cost advantage over gas can disappear, especially if gas is cheap in your area. This is why climate zone matters so much, and why this calculator applies a seasonal COP adjustment rather than using the rated number.

The IRA (Inflation Reduction Act) Section 25C credit provides 30% of the installed cost of a qualifying heat pump, capped at $2,000 per year. On a $12,000 system, the math would give $3,600 at 30%, but the cap limits the credit to $2,000. You must owe federal income tax to use a nonrefundable credit.

Several states add their own incentives. Massachusetts, Maine, New York, and others offer rebates from $1,000 to $10,000. Some utility companies offer additional rebates through efficiency programs. The combination of federal and state incentives can cut the net cost of a heat pump by 30% to 50%, substantially changing the payback math.

Check the DSIRE database (dsireusa.org) for current incentives in your state. Programs change frequently, and some have income limits or enrollment caps.

Gas furnaces are not obsolete. In regions with very cheap natural gas and expensive electricity, a high-efficiency (96% AFUE) gas furnace can be the cheaper option over 15 years. This is especially true in IECC Climate Zones 6 and 7, where the cold-weather COP penalty is largest and heating demands are highest.

If your existing furnace is relatively new (under 10 years) and high-efficiency, the incremental savings from switching to a heat pump may not justify the upfront cost for years. Run the numbers with your actual equipment age and efficiency rating.

One factor this calculator does not model: comfort. Some homeowners in very cold climates report that heat pumps deliver air at a lower temperature than gas furnaces (90-100 degrees F vs 120-140 degrees F), which can feel drafty despite maintaining the thermostat setpoint. Modern cold-climate heat pumps have largely addressed this, but it is worth discussing with your HVAC contractor.