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Heating cost calculator

Mini-split heat pump vs. gas furnace, propane furnace, and electric baseboard. Defaults are U.S. averages from the EIA, checked Oct 19, 2026.

How much heat you need

From our sizing calculator (heating need) or a Manual J. HDD: roughly 2,000-3,000 in the South, 5,000-6,500 in Chicago/Boston, 7,500+ in Minneapolis. Look up yours with NOAA/NWS climate data.

Your prices
Equipment efficiency

Use the HSPF2 for Region V (cold climates) if you're in zone 5 or colder, Region IV otherwise. Default 7.0 = MRCOOL DIY 12K, Region V.

Heat pump, per year$0
$0Yearly savings vs. propane
-Simple payback vs. propane

The math

Yearly heat (BTU) = heat loss ÷ (65 − design temp) × HDD × 24

  • Heat pump: seasonal COP = HSPF2 ÷ 3.412, so kWh = BTU ÷ 3,412 ÷ COP. HSPF2 is the DOE seasonal heating efficiency rating, in BTU per watt-hour.
  • Electric baseboard: 100% efficient (COP 1): kWh = BTU ÷ 3,412.
  • Gas furnace: therms = BTU ÷ 100,000 ÷ AFUE.
  • Propane furnace: gallons = BTU ÷ 91,452 ÷ AFUE.

The degree-day method is a standard simplified estimate. It ignores heat from people and appliances, and it uses one seasonal efficiency number, so treat results as a ballpark, not a bill. On the coldest days a heat pump's efficiency and output both drop, and some homes need backup heat; HSPF2 already averages that across a season.

Tax credits: the federal 25C credit for heat pumps does not apply to equipment placed in service after December 31, 2025 (IRS). Utility and state rebates may still exist; check your utility. Our payback number includes no rebates.

Default prices and sources (checked Oct 19, 2026)

Winter gas prices are usually lower per unit than summer ones because fixed delivery charges are spread over more use, so we use a January figure as the heating-season default.