Methodology

The formula

Cost = (watts ÷ 1,000) × hours of use × duty cycle × rate ($/kWh)

• Monthly = daily cost × 30.42 (average days per month). Yearly = daily cost × 365.
• Per-load appliances (dishwasher, washer, dryer) use energy per load instead: kWh per load × loads per week ÷ 7 per day.
• Always-on appliances (refrigerator, freezer, Wi-Fi router) run 24 hours a day with a duty cycle.
• CO₂ = kWh × the state’s emissions rate of in-state power generation (lb/kWh).

Electricity rates

We use the average retail price of electricity to the residential sector for each state, published monthly by the U.S. Energy Information Administration (EIA) in Electric Power Monthly. It’s total residential revenue divided by kWh sold, so it includes energy, delivery and most fixed charges spread across usage. The current figures are for July 2026, with a US average of 18.3¢/kWh.

• Update schedule: our system checks EIA every day and publishes new numbers as soon as they appear. EIA data typically lags by about two months.
• Validation: new data is only published if all 50 states, DC and the US total are present, every price is within a plausible range, and no state moved more than 35% in a month. Otherwise the previous month stays live and we review it.
• Average bill and usage on state pages are EIA residential revenue and sales divided by the number of residential customers for that month.

Appliance assumptions

Typical wattage, hours of use and duty cycle for each appliance are based on manufacturer specifications, ENERGY STAR data and common measured values. You can change any of them in the calculator.

Why duty cycles matter

Many appliances don’t draw their full rated power all the time. A refrigerator’s compressor runs roughly a third of the day; an oven’s elements cycle once it reaches temperature. Calculators that multiply the sticker wattage by 24 hours overstate these costs by two to three times. We apply a duty cycle where it matters and show it, so you can adjust it to your own appliance.

Limitations

• Your utility’s rate can differ from the state average, especially with time-of-use, tiered or retail-choice plans. Enter your own rate for the most accurate result.
• Real-world use varies with climate, insulation, settings and appliance age.
• CO₂ figures reflect in-state generation and don’t account for electricity imported from other states or your utility’s specific mix.

Corrections

Found something that looks wrong? Email hello@applicost.com and we’ll check it against the source.