Energy Density and Conversion: The Math You Need
Propane and natural gas are priced in different units and have different energy densities, making direct comparison confusing. Natural gas is priced per therm (100,000 BTU) or per thousand cubic feet (MCF = roughly 10 therms). Propane is priced per gallon (91,547 BTU/gallon ≈ 0.915 therms/gallon). To compare costs on equivalent terms: at $1.40/therm for gas, you'd need propane at $1.28/gallon to break even (1.40 × 0.915). National average propane prices run $2.00–$3.00/gallon ($2.18–$3.28/therm equivalent) — making propane consistently 50–130% more expensive than natural gas on an energy-equivalent basis in most years.
Why Propane Prices Vary So Much More Than Gas
Natural gas is delivered via pipeline — a regulated utility infrastructure with relatively stable retail rates. Propane is a liquid commodity delivered by truck, with prices tied to wholesale propane markets (which correlate with crude oil) plus local delivery costs. Propane prices spike significantly in winter when demand surges and can double in cold snaps. Rural propane customers also face higher delivery costs than suburban areas. The price volatility risk is a real financial consideration for propane-dependent households, especially in Northern states where heating season is long and demand peaks are severe.
When Propane Is the Only Viable Option
Propane exists as a residential fuel because natural gas pipeline infrastructure doesn't reach everywhere. About 10% of U.S. households use propane, concentrated in rural areas without gas mains. If you're in a rural area and need gas appliances (furnace, range, water heater, dryer), propane is often the choice between: propane, electric, or oil. In recent years, with heat pump technology maturing, the propane vs. heat pump decision has become the more relevant one for many rural households — particularly as HPWH, heat pump furnaces, and induction ranges now replace every major propane appliance with electric alternatives that are often cheaper to operate even at rural electricity rates.
The Electrification Case for Propane Households
Propane households pay a significant premium for fuel — $800–$2,000/year more than equivalent gas households in many cases. This creates a strong financial case for appliance electrification: heat pump for heating (saves $400–$1,200/year vs. propane furnace), heat pump water heater (saves $300–$700/year vs. propane water heater), induction range (saves $50–$150/year). Combined, a full electrification of a propane home's major appliances can save $750–$2,000/year in fuel costs. Note that the IRA's federal tax credits for heat pumps and HPWHs expired December 31, 2025 — the switch still pencils out for many propane households on fuel savings alone, just with a longer payback than when the credit was active.