Energy Cost Calculator

What the calculator adds up

The calculator takes two inputs for each of the four fuels: how much your household used over a year and what one unit costs. Annual cost = units x price per unit, and the four lines add up to the household total. Next to each cost it shows the same fuel priced in dollars per million Btu, the number that makes the fuels comparable. Each row also carries a 10 percent cut, which is what using 10 percent less of that fuel returns in a year.

Fill in only the fuels your household burns. A house on the gas grid usually has two lines, electricity and natural gas. A rural house often swaps the gas line for a propane tank or an oil tank, and some houses run propane heat with electric everything else. Leave a line at zero and it drops out of the total.

One unit note: natural gas bills quote therms or Ccf, and the calculator wants therms. Treat a Ccf as a therm for a first pass; they differ by about 4 percent, because a hundred cubic feet holds roughly 103,700 Btu against the therm's flat 100,000. Electricity shows up as kilowatt hours, propane and heating oil as gallons.

The four Btu constants behind every comparison

A Btu is the heat needed to warm one pound of water by 1 degree Fahrenheit, and a million Btu, written MMBtu, is the yardstick for whole house energy. Every fuel can be restated in those terms once you know its heat content per billing unit. Four constants do all the work:

Read one row across and the units stop being foreign: 293.1 kilowatt hours, 10 therms, 10.93 gallons of propane and 7.22 gallons of heating oil all deliver the same heat. The calculator uses these constants exactly as printed. They are rounded from the conversion table the U.S. Energy Information Administration publishes in its guide to British thermal units, which lists heating oil at 138,500 Btu per gallon and propane at 91,452 Btu per gallon; the 48 Btu gap on propane moves a cost estimate by well under a cent per MMBtu.

Why a cent per kWh and a dollar per gallon cannot be compared

A gallon and a kilowatt hour are containers, not amounts of energy, so their price tags sit on different scales. A rate that looks cheap per container can be expensive per unit of heat, and the only honest fix is to restate every price in the same unit: dollars per million Btu. The formula is cost per MMBtu = price per unit / (Btu per unit / 1,000,000).

Run the two most common fuels through it. At the 2025 average residential electric rate of 17.30 cents per kWh, 0.173 / 0.003412 = 50.70, so electricity costs $50.70 per MMBtu. At $1.475 per therm, 1.475 / 0.1 = 14.75, so natural gas costs $14.75 per MMBtu. The same million Btu of heat costs 3.4 times more when it arrives as electricity.

This is also why sticker prices mislead in the other direction. A $0.15 per kWh electric rate sounds cheaper than $2.50 per gallon propane, but the electric rate is 43.96 dollars per MMBtu and the propane is 27.32. Whichever pair of bills lands on your kitchen table, dividing by the Btu content is the step that turns two unrelated numbers into one ranking.

What EIA prices looked like in 2025

The U.S. Energy Information Administration tracks residential fuel prices all year, and its price summary carries the annual averages and the near term forecast. The 2025 annual averages put electricity at 17.30 cents per kWh and natural gas at $15.30 per thousand cubic feet, and a thousand cubic feet holds about 1.037 MMBtu, which is $14.75 per MMBtu. Heating oil averaged $3.62 a gallon for 2025. Propane is published weekly during the heating season in the heating oil and propane update, and the U.S. residential average stood at $2.69 a gallon for the week of October 19, 2026.

State spreads are wide. In 2025 the average retail electric price across all customer types ran from 35.72 cents per kWh in Hawaii down to 8.20 cents in North Dakota, and propane runs cheaper in the Midwest than on the East Coast. The averages set the scene; the price printed on your own bill is the one that belongs in the calculator.

Worked example: 9,600 kWh and 640 therms

Take a 1,900 square foot house in Ohio that burned 9,600 kWh of electricity at 17.30 cents and 640 therms of natural gas at $1.475. The electric line is 9,600 x 0.173 = 1,660.80 dollars and the gas line is 640 x 1.475 = 944 dollars, so the household total is $2,604.80 for the year.

The blended price for the whole house works out to 2,604.80 / 96.76 = 26.92 dollars per MMBtu, a number that means little until another house sits next to it. The swap test is where the ranking earns its keep: the same 64 MMBtu the furnace delivered takes 699 gallons of propane, which at $2.69 a gallon is $1,880, or 462 gallons of heating oil at $3.62 for $1,672. Gas at $944 wins that heat-off because a therm carries the most Btu per dollar. Equipment efficiency shifts the ranking a little, and that adjustment comes next.

Heating, cooling and hot water drive the total

EIA's Residential Energy Consumption Survey puts space heating and air conditioning at 52 percent of home energy use as of 2020, water heating, lighting and refrigeration at another 25 percent, and every television, washer and game console combined at 23 percent. The fuel that heats the house is therefore the line worth comparing hardest, and the plug load line moves less than people expect.

Raw price per MMBtu is still not the last word, because combustion furnaces lose part of their heat up the flue while an electric baseboard loses almost none indoors. Adjust each fuel for equipment efficiency and the delivered cost of heat rearranges:

AFUE, annual fuel utilization efficiency, is the share of the fuel's heat that reaches the living space over a season, the ENERGY STAR product pages list certified furnace ratings with their AFUE. Divide the fuel's dollars per MMBtu by that share to get the delivered number. Efficiency narrows the gap between fuels but does not close it: even at 80 percent, gas still delivers heat for about a third of what baseboard electricity costs.

How a heat pump changes the arithmetic

A heat pump does not burn fuel to make heat, it moves heat from outside air or ground into the house, so one kilowatt hour can carry several units of heat. ENERGY STAR notes that a certified air source heat pump can deliver up to three times more heat energy to a home than the electrical energy it consumes, and estimates average savings of $460 a year switching from electric resistance heat and about $950 a year switching from oil.

In per MMBtu terms the move is a division. At the 2025 average electric rate, resistance heat costs $50.70 per MMBtu of delivered heat, so a heat pump running at a coefficient of performance of 3 turns that into 50.70 / 3 = 16.90, which beats an 80 percent gas furnace at $18.44. In a cold snap when the coefficient drops to 2, the cost becomes 25.35, about the level of raw propane. That is why the same electric bill can be the cheapest heat on the street in spring and the most expensive in January.

The calculator compares fuel prices, not equipment. To fold a heat pump in, treat its electric use as resistance use divided by the coefficient of performance you expect for your climate, usually between 2 and 4 for a modern unit, and remember the installation cost is a separate decision with a separate payback.

Ten percent cuts, ranked by what they return

The last column of the calculator applies a 10 percent cut to each fuel line, which is a fair stand in for the savings most households can find without replacing equipment. In the worked example that is $166.08 off electricity, $94.40 off gas, and $260.48 off the total.

The Department of Energy puts a number on the easiest one: turning the thermostat back 7 to 10 degrees for 8 hours a day saves as much as 10 percent a year on heating and cooling, which on this house covers the whole electric cut by itself. Setting the water heater to 120 degrees, swapping remaining bulbs for LEDs, sealing leaky ducts and keeping filters clean are the other free moves, and none of them needs a contractor.

Rate shopping and use cutting are different levers. A cheaper rate lowers the price per unit across the board, while a 10 percent use cut shrinks the bill by the same share on any rate. The calculator shows the value of the second lever directly, and your utility's tariff sheet sets the first.