What does it actually cost to heat your house?

How to read the numbers

A gallon of heating oil, a gallon of propane, a therm of gas and a kilowatt-hour of electricity all hold different amounts of energy, and your furnace or boiler wastes some of whatever it burns. So the price on the delivery ticket tells you almost nothing about which fuel is cheaper. The only fair comparison is the cost of a million BTU of heat that actually reaches your living room. That is what the ranked list shows.

Three things move the ranking. The price you pay per unit of fuel, which varies more by town and by week than most people think. The heat content of the fuel, which is fixed. And the efficiency of the equipment, which is where a 1985 oil boiler at 75% and a condensing propane boiler at 95% end up fifteen points apart before either one has burned a drop.

Heat pumps are the exception that confuses everyone. They don't make heat, they move it, so their "efficiency" runs well above 100%. A cold-climate air-source unit averages around 2.5 units of heat per unit of electricity across a northern winter, which is why electricity at 23¢ a kilowatt-hour can beat oil at $3.70 a gallon. On a single-digit night that same unit may drop to 1.5, and the ranking flips for the night. The seasonal figure is what matters for your annual bill; the cold-night figure is what matters for sizing a backup.

The annual estimate

The yearly dollar figures are an estimate of how much heat a house your size needs in your state's climate, using heating degree days and a per-square-foot factor for the building envelope. A typical 2,000-square-foot home in Vermont needs roughly 90 million BTU of delivered heat a year; the same house in Virginia needs about half that. If you know your actual fuel use, the per-BTU column is the number to trust and you can multiply it yourself: gallons of oil × 0.1385 × your boiler's efficiency gives delivered million BTU.

What this calculator doesn't do

It compares the cost of fuel, not the cost of switching. A new cold-climate heat pump, a propane conversion or a pellet stove each have an installed cost, a lifespan and, depending on the year and your state, rebates and tax credits that change the math. The fuel-cost gap tells you how fast that investment pays back; it doesn't tell you whether to make it. It also doesn't include chimney cleaning, annual service, tank rental, delivery minimums or the electricity a furnace blower uses. Those are real, and they are usually small next to the fuel itself.

Full sources, heat content values and the efficiency assumptions are on the methodology page.