Home › Heating cost by state › Illinois

Heat pump vs gas furnace in Illinois: heating cost by fuel (2026)

At Illinois's average prices, a heat pump (COP 2.5) delivers heat for $22.53 per million BTU, versus $11.62 for a 95% gas furnace, $22.36 for propane and $50.20 for heating oil. That makes the heat pump more expensive than a new gas furnace here. It breaks even with gas at a seasonal COP of 4.85.

Heat pump, est. per year$1,320COP 2.5; $1,650 at COP 2.0, $1,100 at COP 3.0

Gas furnace, est. per year$68195% AFUE; $809 at 80%

Propane, est. per year$1,310heat pump breaks even at COP 2.52

Heating oil, est. per year$2,941heat pump breaks even at COP 1.12

Cost per unit of heat in Illinois, cheapest first

System	$ per MMBtu delivered	Est. per year (58.6 MMBtu)
Gas furnace, 95% AFUE	$11.62	$681
Older gas furnace, 80% AFUE	$13.80	$809
Propane furnace, 95% AFUE	$22.36	$1,310
Heat pump (seasonal COP 2.5)	$22.53	$1,320
Heating oil furnace/boiler, 85%	$50.20	$2,941
Electric resistance (baseboard/furnace), 100%	$56.33	$3,300

The Illinois inputs

Electricity: 19.22¢/kWh, residential average year-to-date through July 2026 (EIA Electric Power Monthly). U.S.: 18.19¢.
Natural gas: $11.44 per thousand cubic feet, average of EIA monthly residential prices for Oct 2025–Mar 2026 (6 months reported). U.S.: $15.60.
Propane: $1.94/gal, week of Oct 19, 2026 (a year earlier: $1.74); EIA state series. EIA weekly prices exclude taxes.
Heating oil: $5.91/gal, week of Oct 19, 2026 (a year earlier: $3.30); EIA regional average: PADD 2. Excludes taxes.
Climate: 5,858 heating degree days per year (base 65°F); NOAA CPC population-weighted state average, 2011–2025.

Heating cost calculator

State

Heating degree days / yr

Heat needed per degree day (BTU)

Heat pump seasonal COP

Gas furnace AFUE (%)

Electricity (¢/kWh)

Natural gas ($/Mcf)

Propane ($/gal)

Heating oil ($/gal)

Defaults are the state's latest EIA prices and NOAA degree days; the BTU-per-degree-day, COP and efficiency values are our assumptions. Put in your own bill rates and a known annual heat use for a better answer. Runs in your browser; nothing is sent anywhere. Tip: 1 therm = 0.1 MMBtu; $/therm × 10.36 ≈ $/Mcf.

Assumptions (ours, not EIA/NOAA figures): heat pump seasonal COP 2.5 (we also show 2.0 for very cold climates and 3.0 for mild ones); gas furnace 95% AFUE (older units ~80%); propane furnace 95%; oil 85%; electric resistance 100%. Annual totals assume a home that needs 10,000 BTU of delivered heat per heating degree day, a round number for an existing house; a tight new home may need half that, a drafty one more. The per-MMBtu comparison does not depend on house size. Prices exclude equipment, installation, maintenance, fixed monthly utility charges and rebates. Method & sources.

More for Illinois

EV vs gas car cost in Illinois · Cost to run a space heater · Electric blanket · All states compared · When does it first snow in Illinois? (sister site)