Heat Pump vs. Gas/Oil Cost Calculator

Against natural gas it is genuinely close, and the answer depends on your local rates rather than on the technology. At a typical electricity rate with a seasonal COP around 3, a heat pump delivers heat for roughly $14 to $16 per million BTU, and a 95% gas furnace at a middling gas price lands in much the same range — so the winner can flip either way with a few cents’ movement in either rate. That is exactly why the calculator reports a break-even fuel price: it tells you the gas price at which the two tie, so you can watch one number instead of redoing the maths. Where electricity is cheap relative to gas, the heat pump wins comfortably; where gas is cheap and power is expensive, the furnace does.

COP, or coefficient of performance, is how many units of heat the unit moves for each unit of electricity it consumes — a COP of 3 means three times more heat out than power in, which is possible because a heat pump moves existing heat rather than creating it. HSPF2 measures the same thing across a whole heating season but in mixed units, so dividing HSPF2 by 3.412 converts it to a seasonal COP; an HSPF2 of 9, for instance, is about COP 2.6. SEER2 is a cooling efficiency rating and tells you nothing about heating cost. The calculator accepts either COP or HSPF2 and converts between them when you switch the rating basis.

They work, but efficiency falls as the temperature drops, and that is what the comparison has to account for. Modern cold-climate models using variable-speed compressors hold useful output well below freezing and many are rated to keep heating into negative temperatures, though the COP at those conditions is meaningfully lower than the mild-weather rating on the box. The real risk to the economics is backup heat: if the system is undersized or set to hand off to electric resistance strips early, those hours run at COP 1.0 and cost roughly three times as much as heat-pump heat. Set the backup slider to a realistic share of the season and the calculator will show you the effective COP you actually pay for.

The most accurate route is your own bills. Add up the therms or gallons you burned over a full heating season, multiply by the fuel’s energy content — about 100,000 BTU per therm, 138,500 per gallon of oil, 91,500 per gallon of propane — then multiply by your furnace efficiency to get the heat actually delivered into the house. Divide by a million and that is your load in MMBTU. Subtract summer usage first if the same fuel runs your water heater or range. If you would rather not dig through bills, the calculator estimates a load from your square footage and climate, which is fine for a first look but worth replacing with the real figure before you make a decision.

This is where heat pumps usually win by a wide margin rather than a narrow one. Delivered fuels cost far more per unit of heat than piped gas — at common prices, oil and propane often land near double or more the cost per million BTU of a heat pump running at a seasonal COP around 3. That gap is large enough that it tends to survive a cold winter, a mediocre COP and a fair amount of backup heat. Run your own last delivery price through the calculator rather than trusting an average, since delivered fuel pricing varies enormously by region, contract and how much you take at a time.

Yes, and that alone is not a reason to worry — the question is what happens to your total heating spend. Moving your heat onto electricity naturally raises the electric bill while the gas, oil or propane bill falls or disappears, so a bigger power bill can still mean less money out the door overall. Two practical cautions: check whether your utility has a winter rate tier or demand charge that changes the effective price of that extra usage, and confirm your electrical panel and service can carry the new load, since an upgrade is a real cost that belongs in the install premium field. The calculator shows the heat pump’s annual kWh so you can see the size of the increase before it arrives.