Therms to kWh Converter and Energy Unit Calculator

Home energy comes in confusing units. Your gas bill shows therms or CCF, your electric bill shows kilowatt-hours, and propane and heating oil are sold by the gallon. This therms to kWh converter turns any of them into all the others, so you can see how much energy you are really buying.

How the calculation works

Every unit is converted to BTU (British thermal units) first, then from BTU to each other unit.

BTU          = amount × BTU per unit
Other unit   = BTU ÷ BTU per that unit

The BTU values come from the U.S. Energy Information Administration (EIA):

The kWh, therm and propane factors appear in EIA’s units and calculators table. The CCF value uses EIA’s 2025 US average heat content of natural gas delivered to customers, about 1,037 BTU per cubic foot (EIA FAQ). The heating oil value, 137,381 BTU per gallon, is EIA’s factor for ultra-low-sulfur distillate fuel. EIA’s general table lists heating oil at 138,500 BTU, less than 1 percent higher.

Worked example

The default input is 100 therms of natural gas.

1. BTU: 100 × 100,000 = 10,000,000 BTU (10.000 MMBtu).
2. kWh: 10,000,000 ÷ 3,412 = 2,930.83 kWh.
3. CCF: 10,000,000 ÷ 103,700 = 96.43 CCF.
4. Propane: 10,000,000 ÷ 91,452 = 109.35 gallons.
5. Heating oil: 10,000,000 ÷ 137,381 = 72.79 gallons.

A second example

Your gas bill shows 80 CCF for the month. The converter shows that is 82.96 therms, 8,296,000 BTU and 2,431.42 kWh of energy. If your utility prints a therm factor on the bill, multiply your CCF by that factor for a more exact local figure.

For a propane home, a 500-gallon fill holds 45,726,000 BTU: the same energy as 457.26 therms of natural gas, 13,401.52 kWh of electricity, or 332.84 gallons of heating oil.

What your result means

The converter tells you how much energy is in an amount of fuel. It does not tell you how much useful heat you get, because every appliance wastes some energy, and heat pumps move more heat than the electricity they use.

For example, 100 therms of gas is 2,930.83 kWh of energy. A gas furnace that is 90 percent efficient turns about 90 percent of it into heat in your home. Electric resistance heat turns about 100 percent of electricity into heat. A heat pump moves heat rather than making it, so it can deliver more heat than the electricity it uses; how much depends on its rating and the weather. So the kWh you would actually buy to replace 100 therms depends on the equipment.

To compare the real cost of heat from each fuel, use the heating cost comparison calculator. If you heat with propane or oil and wonder whether a heat pump works where you live, see our cold-climate heat pump guide. To estimate savings from switching to a heat pump, try the heat pump savings calculator, and read our heat pump cost and savings guide.

What changes the numbers

Local gas quality. Natural gas heat content varies by location and over time. EIA notes its factors are recalculated each year. Utilities convert your CCF into therms using a local factor, often printed on the bill.

Heating oil type. Higher-sulfur heating oil has slightly more energy per gallon than ultra-low-sulfur fuel. The difference is small, under 1 percent between EIA’s two listed values.

Propane and oil deliveries. Convert the gallons actually delivered, as shown on your delivery ticket, not the size of the tank.

Prices. EIA’s Heating Oil and Propane Update reported average residential prices of about $2.64 per gallon for propane and $6.14 per gallon for heating oil for the week of October 12, 2026. Your local price may differ.

Common mistakes

• Treating CCF and therms as the same. They are close but not equal: 1 CCF is about 1.037 therms.
• Mixing up kW and kWh. kW is a rate of power; kWh is an amount of energy. Bills charge for kWh.
• Confusing BTU and BTU per hour. Equipment is rated in BTU per hour. Fuel amounts are in BTU.
• Comparing fuels by energy alone. Efficiency matters. Use a cost comparison that includes it.
• Using tank size instead of gallons delivered. Check your propane or oil delivery ticket.

Limits of this calculator

The converter uses fixed national average heat contents. It does not account for your utility’s local therm factor, seasonal changes in gas quality, fuel blends, or appliance efficiency. Results are rounded for display.

It gives an educational estimate, not a billing calculation or advice. For bill math with your rates, see the electric bill calculator, and for ways to use less of any fuel, our guide on how to lower your energy bill.