How these figures are calculated

The formula

cost = (watts ÷ 1000) × hours × duty cycle × price per kWh

Watts divided by 1,000 gives kilowatts. Multiplied by hours it gives kilowatt-hours, the unit your utility bills. Multiplied by the price per kilowatt-hour it gives money.

The duty-cycle correction

This is the part most calculators leave out, and it is the difference between a useful estimate and a wrong one.

Many large appliances do not draw power continuously. A refrigerator is plugged in 24 hours a day, but its compressor runs roughly a third of that time — the rest of the time it is coasting. The same is true of freezers, air conditioners, dehumidifiers, electric water heaters and hot tubs.

A calculator that multiplies 150 watts by 24 hours reports a refrigerator costing about three times what it actually costs. Every cycling appliance on this site carries an explicit duty cycle, shown on its page, and the calculator applies it.

Where the wattages come from

There is no authoritative national table giving “the” wattage of a household appliance, because draw varies by model, size, age and setting. Publishing a single number as though it were a measured fact would be misleading.

So each appliance page shows a range with a stated basis explaining where those bounds come from — usually a circuit limit, a standard component rating, or the span between the smallest and largest common model. The typical value is a starting default, not a measurement, and the calculator lets you replace it with the figure printed on your own appliance’s label. That figure is always better than our default.

Where the prices come from

Average residential electricity prices for all 50 states and the District of Columbia come from the U.S. Energy Information Administration’s Electric Power Monthly, Table 5.6.A. The current figures describe June 2026, the latest month published, and were retrieved on 2026-08-31.

EIA data is a work of the U.S. government and is in the public domain. We reproduce it without modification; the ranking, comparison and cost arithmetic are ours.

What these figures exclude

• Fixed monthly charges and connection fees, which every utility bills regardless of usage.
• Taxes and local surcharges.
• Time-of-use, tiered and demand rates. Many utilities charge more at peak hours and less overnight; a single average cannot represent that.
• The difference between your specific utility and the statewide average, which can be substantial.
• Standing losses, ambient temperature and installation quality, all of which affect real consumption.

These figures are for comparison and rough budgeting. For an exact number, use the price per kilowatt-hour printed on your own bill and, if you want certainty about one appliance, a plug-in energy meter.

Corrections

If a figure here is wrong, we want to fix it. Tell us and include the source you are comparing against. Corrections are dated and recorded rather than silently edited, for the reasons set out in why this site exists.