★ CONSTRUCTION · HOME · COMPARISONS
A heat pump costs $714.36 a year to heat a 60 MMBtu home, against $1,263.16 for a 95% gas furnace. The heat pump saves $548.80 a year, pays back its higher install price in 9.11 years, and ends up $487.97 ahead after 10 years and $3,231.96 ahead after 15.
A heat pump moves heat instead of making it, so one unit of electricity becomes three or more units of heat. A gas furnace burns fuel, so it can never beat 100% efficiency. Enter your home’s heat demand, your energy prices, and both install prices to see which one costs less — this year, and over the life of the system.
The two systems heat your home in opposite ways. A furnace burns gas and turns at most 95% of it into heat — the other 5% goes up the flue. A heat pump does not make heat at all: it moves heat from the outside air into your home, like a refrigerator running in reverse, so one kilowatt-hour of electricity becomes 3.2 kilowatt-hours of heat at the default COP. That is why the heat pump’s running cost is lower even though electricity costs more per unit of energy than gas: it uses far fewer units.
At the defaults — 60 MMBtu of heat a year, COP 3.2, electricity $0.13/kWh, furnace AFUE 95%, gas $2.00/therm, heat-pump install $9,500, furnace install $4,500 — the heat pump needs 60 ÷ 3.2 × 293.071 = 5,495.08 kWh a year, costing 5,495.08 × $0.13 = $714.36. The furnace needs 60 ÷ 0.95 × 10 = 631.58 therms, costing 631.58 × $2.00 = $1,263.16. The saving is $1,263.16 − $714.36 = $548.80 a year, and the $5,000 install gap pays back in $5,000 ÷ $548.80 = 9.11 years.
| Item | Heat pump | Gas furnace |
|---|---|---|
| Annual energy use | 5,495.08 kWh | 631.58 therms |
| Annual heating cost | $714.36 | $1,263.16 |
| Install price | $9,500.00 | $4,500.00 |
| 10-year total | $16,643.61 | $17,131.58 |
| 15-year total | $20,215.41 | $23,447.37 |
| Also cools in summer | Yes — it is an air conditioner in reverse | No — needs a separate AC unit |
| Efficiency ceiling | 300%+ (COP 3.2 = 320%) | 98% at best (AFUE 98) |
Setup: heat demand 60 MMBtu; COP 3.2; electricity $0.13/kWh; AFUE 95%; gas $2.00/therm; heat-pump install $9,500; furnace install $4,500.
Line 1 — heat-pump electricity. 60 ÷ 3.2 × 293.071 = 5,495.08 kWh. One MMBtu is 293.071 kWh of heat, and the COP of 3.2 means each kWh of electricity delivers 3.2 kWh of heat.
Line 2 — heat-pump annual cost. 5,495.08 × $0.13 = $714.36.
Line 3 — furnace gas use. 60 ÷ 0.95 × 10 = 631.58 therms. One MMBtu is 10 therms, and the 95% AFUE means 5% of the gas’s heat is wasted.
Line 4 — furnace annual cost. 631.58 × $2.00 = $1,263.16.
Line 5 — annual saving. $1,263.16 − $714.36 = $548.80 a year in the heat pump’s favour.
Line 6 — payback. ($9,500 − $4,500) ÷ $548.80 = 9.11 years.
Line 7 — 10-year totals. Heat pump: $9,500 + 10 × $714.36 = $16,643.61. Furnace: $4,500 + 10 × $1,263.16 = $17,131.58. Heat pump ahead by $487.97.
Line 8 — 15-year totals. Heat pump: $9,500 + 15 × $714.36 = $20,215.41. Furnace: $4,500 + 15 × $1,263.16 = $23,447.37. Heat pump ahead by $3,231.96.
Line 9 — break-even gas price. $714.36 ÷ 631.58 therms = $1.131 a therm. If gas fell to that price, the furnace would tie the heat pump.
COP 3.8: a more efficient heat pump uses 60 ÷ 3.8 × 293.071 = 4,627.44 kWh, costing $601.57 a year. The saving grows to $661.59 a year and payback shrinks to 7.56 years. In a mild climate, where the seasonal COP really is 3.8, the heat pump is a clear win.
Gas at $1.40 a therm: the furnace costs 631.58 × $1.40 = $884.21 a year. The saving shrinks to $169.85 a year and payback stretches to 29.44 years — longer than most heat pumps last, so cheap gas flips the answer.
Electricity at $0.20/kWh: the heat pump costs 5,495.08 × $0.20 = $1,099.02 a year. The saving shrinks to $164.14 a year and payback stretches to 30.46 years. Expensive electricity hurts the heat pump more than anything else, because every kWh it buys is multiplied by the price.
AFUE 80%: an old furnace needs 60 ÷ 0.80 × 10 = 750 therms, costing $1,500.00 a year. The saving grows to $785.64 a year and payback shrinks to 6.36 years. Replacing a tired old furnace is where the heat pump pays back fastest.
Reverse — the break-even gas price: the furnace ties the heat pump when gas costs $1.131 a therm — $714.36 ÷ 631.58 therms. At the default $2.00 a therm, gas would have to fall by almost half before the furnace caught up.
The single COP of 3.2 is a seasonal average: a heat pump’s COP is higher on a mild autumn day and lower on a freezing night, because there is less heat to pull out of colder air. The figure here is the average across the whole heating season in a moderate climate; in a very cold climate the seasonal COP can fall toward 2.0, and in a warm one it can rise past 4.0. The heat pump also cools in summer — it is an air conditioner running in reverse — and those cooling savings are not costed here, so the heat pump’s real advantage is a little bigger than the numbers show if it replaces a separate air conditioner. The figures exclude maintenance and ductwork: both systems need servicing, and a heat pump in a home with leaky old ducts may need duct work that a furnace swap would not. Energy prices are held flat for the 10- and 15-year totals, and no rebates or tax credits are subtracted from the install prices — in practice, federal and state incentives can cut the heat pump’s install price by thousands and shorten the payback a lot. Rounding convention: money is rounded to cents and all figures are computed from unrounded values, rounded only for display.
| Output | Formula | What it means |
|---|---|---|
| Heat-pump electricity | demand ÷ COP × 293.071 | 5,495.08 kWh a year. |
| Heat-pump annual cost | kWh × electricity price | $714.36 a year. |
| Furnace gas use | demand ÷ (AFUE ÷ 100) × 10 | 631.58 therms a year. |
| Furnace annual cost | therms × gas price | $1,263.16 a year. |
| Annual saving | furnace cost − heat-pump cost | $548.80 a year. |
| Payback period | (heat-pump install − furnace install) ÷ saving | 9.11 years. |
| 10-year total, heat pump | install + 10 × annual cost | $16,643.61 — ahead by $487.97. |
| 10-year total, furnace | install + 10 × annual cost | $17,131.58. |
| 15-year total, heat pump | install + 15 × annual cost | $20,215.41 — ahead by $3,231.96. |
| 15-year total, furnace | install + 15 × annual cost | $23,447.37. |
| COP 3.8 | same demand, COP 3.8 | $601.57 a year; saving $661.59; payback 7.56 years. |
| Gas $1.40/therm | same demand, gas $1.40 | $884.21 a year; saving $169.85; payback 29.44 years. |
| Electricity $0.20/kWh | same demand, electricity $0.20 | $1,099.02 a year; saving $164.14; payback 30.46 years. |
| AFUE 80% | same demand, AFUE 80 | $1,500.00 a year; saving $785.64; payback 6.36 years. |
| Reverse: break-even gas price | heat-pump cost ÷ furnace therms | $1.131/therm ties the furnace to the heat pump. |
The math is exact for the numbers you enter: electricity is demand divided by COP times 293.071 kWh per MMBtu, gas is demand divided by AFUE times 10 therms per MMBtu, and payback is the install gap divided by the annual saving. What the model cannot do is know your climate or your house: the single COP is a seasonal average that hides how cold your coldest nights get, and the heat demand itself is an estimate — a draughty house needs more MMBtu than a tight one of the same size, so the absolute dollar figures move even when the winner does not. It also leaves out maintenance, ductwork, and rebates, holds energy prices flat for 10 and 15 years, and does not count the heat pump’s summer cooling, which makes the heat pump look slightly worse than it really is if it replaces an air conditioner. For the cooling side of the same decision, see the space heater vs central heat calculator; for the fuel side, see tank vs tankless water heater.
Bright Side Kit. "Heat Pump vs Furnace Calculator: Which Costs Less?" https://brightoolbox.com/heat-pump-vs-furnace/ Accessed October 24, 2026.At the defaults, the heat pump — by $548.80 a year. Heating a 60 MMBtu home costs $714.36 a year with a heat pump at COP 3.2 and $0.13/kWh, against $1,263.16 a year for a 95% gas furnace at $2.00 a therm. The heat pump moves heat instead of making it, so it needs far less energy.
COP is units of heat delivered per unit of electricity. A COP of 3.2 means one kilowatt-hour of electricity becomes 3.2 kilowatt-hours of heat — 320% efficient, which is possible because the heat pump moves heat from outside instead of creating it. COP falls on the coldest nights, so the 3.2 here is a seasonal average.
AFUE is the percentage of the gas’s heat that reaches your home. A 95% AFUE furnace turns 95 cents of every gas dollar into heat and loses 5 cents up the flue; an old 80% furnace loses 20 cents. At 60 MMBtu, a 95% furnace burns {M['th']:,.2f} therms a year, while an 80% furnace burns 750 therms.
9.11 years at the defaults. The heat pump costs $5,000 more to install ($9,500 against $4,500) and saves $548.80 a year, so $5,000 ÷ $548.80 = 9.11 years. After that it keeps saving $548.80 a year: $487.97 ahead at 10 years, $3,231.96 ahead at 15.
Gas would have to fall to $1.131 a therm for the furnace to tie the heat pump. At $1.40 a therm the furnace costs $884.21 a year and payback stretches to 29.44 years — longer than the system is likely to last, so cheap gas flips the answer.
Yes — it is an air conditioner running in reverse. In summer the same unit moves heat out of your home instead of into it. Those cooling savings are not counted in the figures above, so if the heat pump replaces a separate air conditioner, its real advantage is a little bigger than {money(M['sav'])} a year.
Yes, but the COP falls as it gets colder. On a mild day the COP can be 4 or higher; on a freezing night it can drop toward 2. The 3.2 default is a seasonal average for a moderate climate. In a very cold climate, enter a lower COP — 2.0 or 2.5 — and watch the saving shrink before you decide.
Maintenance, ductwork, and rebates. Both systems need servicing, a heat pump may need duct work a furnace swap would not, and federal and state rebates can cut the heat pump’s install price by thousands. The figures also hold energy prices flat — if gas rises faster than electricity, the heat pump wins by more.