Cost to run: 20 home appliance calculators

Most of an electric bill comes down to one multiplication: how many watts something draws, times the hours it runs, times what your utility charges per kilowatt-hour. The hard parts are the three inputs. Wattage on the label is often a maximum, not what the appliance actually uses. Hours "on" aren't the same as hours running: a thermostat makes a space heater, an air conditioner or a water heater cycle. And the rate depends heavily on where you live. In our reference data, residential electricity ranges from 11.5¢/kWh in North Dakota to 42.0¢/kWh in Hawaii. The same heater costs about 3.7 times as much to run in one state as in the other.

Each calculator here starts from your state's average residential rate from the U.S. Energy Information Administration and shows the month the number comes from. If your bill shows a different rate, type it in. Defaults are the most common wattage for each appliance, taken from DOE and ENERGY STAR figures, so the page never opens empty.

Heating and cooling appliances also get a 12-month curve. A space heater that costs an estimated $49.68 in an average month (US rate, 1,500 W, 6 hours a day) works out to about $121 in January and $0 in July. Pool pumps and dehumidifiers follow the cooling season instead.

Every result has an "Add to my bill" button. Add the appliances you actually run, and the electric bill estimator adds up your month and compares it with your state's average residential bill, also from the EIA. Nothing leaves your browser.

These are estimates, not a meter reading. They leave out fixed customer charges, taxes, tiered and time-of-use pricing. For the exact number, use a plug-in power meter on the appliance and the rate printed on your bill. The formulas and sources behind every page are on our methodology page.