How to use the electric vs gas appliance cost calculator
- Enter the energy one use takes for the electric appliance in kilowatt hours, and your electricity price per kWh.
- Enter the energy one use takes for the gas appliance, in therms or BTU, and your gas price per therm.
- Enter the uses per year. In More options, add the purchase prices of both models to see how long the cheaper-to-run one takes to repay a higher price.
- Read the cost per use and per year for each, and which one costs less to run.
Formula
electric cost = kWh per use x price per kWh
gas cost = therms per use x price per therm
therms = BTU / 100,000
One therm is 100,000 BTU, and one kWh is 3,412.14 BTU, so one therm holds about 29.3 kWh. The page also shows your gas price as dollars per kWh of energy, which lets you compare it directly with the electric rate.
A dryer used 250 times a year
An electric dryer using 3.3 kWh a load at $0.16 per kWh costs 3.3 x 0.16 = $0.528 a load. A gas dryer using 0.25 therms a load at $1.40 per therm costs 0.25 x 1.40 = $0.35 a load. Over 250 loads that is $132.00 for electric and $87.50 for gas, so gas costs $44.50 a year less to run. The gas price works out to $0.0478 per kWh of energy.
Entering the gas use as 25,000 BTU gives the same $87.50. If electricity were $0.05 per kWh, the electric dryer would cost $41.25 a year, and electric would be cheaper by $46.25. With purchase prices of $1,200 for the electric model and $800 for the gas model, the extra $400 would take 400 / 46.25 = 8.6 years to repay.
Where to find the numbers
Electric appliances list their power in watts or amps. Multiply the watts by the hours of use and divide by 1,000 to get kWh per use. A plug-in energy meter gives a direct reading if you have one. Gas appliances list input in BTU per hour, and the energy per use is that rate times the hours it burns. Your bills give both prices, though gas may be billed in hundreds of cubic feet, so convert to therms using the energy value printed on your bill.
The prices in the form are examples, since rates differ by place and change over the year. Use the rate from your latest bill, and if your plan has tiers or time of day rates, use the rate that applies to the hours you run the appliance.
What the comparison leaves out
Only the energy cost is compared. Installation, venting, gas line work, an electrical circuit upgrade, repairs and fixed monthly charges are not included, and they can matter as much as the running cost. Efficiency is built into the energy figures you enter, so use figures for the models you are really considering. The optional purchase prices give a simple payback, not a full cost of ownership.
For related costs, try the Electricity Cost Calculator, the Gas Heating Cost Calculator and the Appliance Replacement Payback Calculator. The BTU Calculator helps with the energy units.
Assumptions and limits
- Energy per use and the two prices are above zero. Uses per year is a whole number from 1 to 100,000.
- Prices stay the same all year, with no tiers, taxes or fixed charges.
- One therm is 100,000 BTU and one kWh is 3,412.14 BTU.
- Nothing is stored or uploaded.
Frequently asked questions
Is it cheaper to run an electric or a gas appliance?
It depends on your local prices and the appliance. Enter the energy per use and both prices, and the page shows the cost per use and per year for each, with the difference. The example dryer costs $44.50 a year less on gas.
How do I convert my gas bill to therms?
Look for the therms used on your bill. If it shows hundreds of cubic feet, multiply by the heating value factor printed on the bill to get therms, then divide the charge by the therms to get a price per therm.
Why show the gas price per kWh?
Because it lets you compare the two fuels on equal terms. If gas is $0.0478 per kWh of energy and electricity is $0.16 per kWh, gas is the cheaper energy even before the appliances differ in efficiency.
Does this include the price of the appliance?
Only in the optional payback. If you enter both purchase prices and the cheaper-to-run model costs more to buy, the page divides the extra price by the yearly savings to show the years to repay it.