Heat Pump Cost Calculator

How the calculator compares the three costs

Every system in the comparison has to put the same heat into your home, so the calculator starts by working out that heat in Btu. Pick where your figure comes from:

• Gas bill: the therms your furnace burns for heating in a year, times 100,000 Btu per therm, times the furnace’s AFUE. 800 therms in an 80% furnace deliver 64,000,000 Btu (64.0 MMBtu) of heat.
• Electric heat: the kWh a year your baseboard heaters or electric furnace use, times 3,412 Btu per kWh. Resistance heat turns each kWh into 3,412 Btu.
• Heat load: the heat in MMBtu a year, if you already know it. 1 MMBtu is 1,000,000 Btu.

Then it prices that heat three ways. A heat pump needs heat ÷ (HSPF2 × 1,000) kWh. A gas furnace needs heat ÷ (100,000 × AFUE) therms. Electric resistance heat needs heat ÷ 3,412 kWh. Each one is multiplied by your price, and the rating plate shows the three yearly costs side by side, with every step in the working.

Finding your heating gas on a bill

A gas bill counts every therm: the furnace, the water heater and the stove. Only the furnace’s share belongs here. A common way to find it is to take the whole year’s gas and subtract 12 times one summer month, when the furnace is off. The “Work it out from a year of bills” panel does this sum for you and prints it. It assumes water heating and cooking use the same gas all year, which is close enough for an estimate.

Some utilities bill in ccf (hundred cubic feet) instead of therms. Pick Ccf and the calculator converts at 1.037 therms per ccf, the US average heat content of natural gas in 2025 (EIA). For the price, use what one therm costs you with delivery charges included, not just the supply line.

Where the answer flips

The plate also shows the break-even points. For the example above, the heat pump costs less to run than the 80% furnace once electricity drops below 14.4 ¢/kWh, once gas rises above $1.87 a therm, or once its rating passes about HSPF2 9.8 (COP 2.88). The idea behind it: a therm of gas holds as much energy as 29.31 kWh of electricity, so the heat pump wins when its COP is high enough to cover the price gap between the two fuels after the furnace’s losses.

A rating is not your winter

HSPF2, the heating rating on heat pump labels since 2023, is a season-long average for a moderate climate. Divide it by 3.412 for the seasonal COP the calculator uses: HSPF2 7.8 is a COP of 2.29, so each kWh of electricity moves about 2.29 kWh of heat into the house. In a hard winter the real figure is lower. A Minnesota field study measured an annual COP of 1.9 for whole all-electric systems, backup heat included, and NREL measured 2.5 for the compressor alone in 12 cold-climate homes. If your winters are cold, switch the rating to COP and try a lower number. Backup heat strips and duct losses are not modelled.

Cooling

If the heat pump will also replace an air conditioner, open “Cooling too” and enter what the old unit uses in a year and its rating. The new unit’s kWh = old kWh × old rating ÷ new SEER2. Ratings printed before 2023 are SEER, a different test from SEER2, so that saving is only a rough guide.

What this page leaves out

It estimates running costs from your bills and your prices. It does not size a heat pump, choose a model, price the installation or count incentives, and it does not cover propane, oil or ground-source systems. Sizing takes a contractor’s load calculation.

Worked example

1. Inputs: 800 therms of heating gas a year in an 80% AFUE furnace; electricity 18.19 ¢/kWh; gas $1.48/therm; heat pump HSPF2 7.8.
2. Heat = gas × 100,000 Btu × AFUE = 800 therms × 100,000 Btu × 0.80 = 64,000,000 Btu (64.0 MMBtu)
3. Seasonal COP = HSPF2 ÷ 3.412 = 7.8 ÷ 3.412 = 2.29
4. Heat pump energy = heat ÷ (HSPF2 × 1,000) = 64,000,000 Btu ÷ (7.8 × 1,000) = 8,205.1 kWh
5. Heat pump cost = 8,205.1 kWh × $0.1819 = $1,493
6. Gas furnace cost = 800 therms × $1.48 = $1,184
7. Resistance heat energy = heat ÷ 3,412 = 64,000,000 Btu ÷ 3,412 = 18,757.3 kWh
8. Resistance heat cost = 18,757.3 kWh × $0.1819 = $3,412
9. Break-even rate = gas cost ÷ heat pump kWh = $1,184 ÷ 8,205.1 kWh = 14.4 ¢/kWh
10. Break-even COP = rate × AFUE × 29.31 ÷ gas price = $0.1819 × 0.80 × 29.31 ÷ $1.48 = 2.88 (HSPF2 9.8)
11. At these prices the gas furnace costs $309 a year less than the heat pump.
12. Costs match at 14.4 ¢/kWh, at $1.87/therm or at HSPF2 9.8 (COP 2.88). The heat pump wins at a lower electricity price, a higher gas price or a higher rating.

Questions people ask