Heating Fuel Cost Comparison Calculator

At average US prices ($1.50/therm gas, $0.16/kWh electric) and standard equipment efficiencies (85% AFUE gas furnace, COP 3.0 heat pump): delivered heat costs are comparable — gas = $17.65/MMBTU, heat pump = $15.63/MMBTU. Electric RESISTANCE heat (baseboards, space heaters, electric furnaces) at COP = 1.0 costs $46.89/MMBTU — approximately 2.7-3.0x more than gas. The key deciding factor: with a modern heat pump, electricity is competitive with or cheaper than gas. Without one (resistance heat only), electricity is dramatically more expensive than any combustion fuel. In regions with very cheap natural gas (<$1.00/therm, Gulf Coast states) or very expensive electricity (>$0.25/kWh, California, Northeast), gas may beat even a high-efficiency heat pump. The break-even COP is: COP_needed = Electricity_Rate x 293.07 x AFUE_gas / Gas_Rate. Plug in your local rates.

The therm (100,000 BTU) is sized appropriately for residential natural gas consumption — a typical single-family home uses 600-900 therms/year for space and water heating combined. The CCF (hundred cubic feet) is a volumetric measure that varies slightly with the gas's heat content; 1 CCF of natural gas typically contains 1.025 therms (102,500-103,000 BTU), depending on the gas composition (methane content, ethane, propane fractions). Your gas bill shows a 'Thermal Factor' or 'BTU Factor' that converts CCF to therms. In wholesale markets and industrial contexts, natural gas is traded in MMBTU (1 MMBTU = 10 therms = ~9.7 CCF). The NYMEX Henry Hub natural gas futures contract is quoted in $/MMBTU — typically $2-6/MMBTU in recent years, which translates to $0.20-0.60/therm for the commodity portion of your bill (the rest is transmission, distribution, and utility margin).

There is no universal answer — it depends entirely on local fuel prices and equipment efficiency. In most of the US, natural gas delivers the lowest $/MMBTU of any combustion fuel because of the extensive pipeline infrastructure and abundant domestic supply. However, modern cold-climate heat pumps (COP 3-4 at moderate temperatures, COP 1.5-2.0 at 0 degrees F) now match or beat gas on operating cost in regions where electricity is moderately priced (<$0.14/kWh) and gas is not unusually cheap (>$1.20/therm). In the Pacific Northwest with $0.08-0.10/kWh hydro electricity, heat pumps dominate gas by a wide margin. In rural areas without gas service, the choice is among propane, fuel oil, and electric heat pump — with propane typically winning on cost and cleanliness versus oil, and heat pumps increasingly competitive as the technology improves. Electric resistance heat (baseboards, space heaters, electric furnaces) is almost always the most expensive heating option, costing 2-3x more than any other fuel on a delivered $/MMBTU basis. Run the numbers for your specific location and utility rates — the right answer changes at every address.

A heat pump's Coefficient of Performance degrades as the temperature difference between the outdoor air (heat source) and the indoor supply air (heat sink) increases. At 47 degrees F (the AHRI standard rating point), most modern air-source heat pumps achieve COP 3.5-4.5. At 17 degrees F (a secondary rating point), COP drops to 2.0-3.0 for standard units and 2.5-3.5 for cold-climate optimized units. At 5 degrees F, standard heat pumps may drop to COP 1.2-1.8 — barely better than resistance heat — while cold-climate heat pumps (with vapor injection or two-stage compression) maintain COP 2.0-2.5. Below -13 degrees F, even cold-climate heat pumps typically shut off and rely on backup resistance or gas heat. The economic balance point — where it becomes cheaper to switch to backup heat — depends on your fuel prices. The HSPF rating provides a seasonally-weighted average that is more useful for annual cost estimation than a single-point COP.

For furnaces and boilers manufactured before 1992 (pre-AFUE mandate), assume 60-68% efficiency for standing-pilot gas units and 56-65% for older oil units. Equipment from 1992-2010 typically has AFUE 78-82% (non-condensing). Post-2010 condensing furnaces achieve 90-98% AFUE. For heat pumps older than 2006 (pre-13 SEER mandate), HSPF was typically 6.8-7.7 (COP 2.0-2.25 seasonal average). Modern standard heat pumps have HSPF 8.2-10 (COP 2.4-2.9). Cold-climate heat pumps achieve HSPF 10-13 (COP 2.9-3.8). If you are unsure of your equipment's age or efficiency, use the AFUE or HSPF printed on the equipment nameplate. If the nameplate is unreadable, estimate based on the equipment's age and general technology level. For precise measurement, a combustion efficiency test by an HVAC technician using a digital flue gas analyzer provides actual steady-state efficiency, though it does not account for cyclic losses.