Electricity cost calculator

From watts to dollars

Electricity is billed in kilowatt-hours (kWh): using 1,000 watts for one hour. Multiply an appliance's watts by the hours it runs and divide by 1,000 to get kWh, then multiply by your rate. The average US residential rate is around 17 cents per kWh, but it ranges from about 11 cents in some states to over 40 cents in Hawaii; your bill shows your exact rate.

Worked examples

A 100 W TV on for 5 hours a day uses 0.5 kWh a day, 15 kWh a month. At $0.16/kWh that is $2.40 a month, about $29 a year.

A 2,000 W space heater for 3 hours a day uses 6 kWh a day: at $0.20/kWh, $36 a month.

Typical wattages

• LED bulb: 8–12 W
• Laptop: 30–60 W; desktop with gaming GPU: 300–600 W
• Refrigerator: 100–250 W average
• Window AC: 500–1,500 W; central AC: 2,000–4,000 W
• Clothes dryer: 2,000–5,000 W

For appliances that cycle, like fridges and air conditioners, the label wattage overstates use; a plug-in power meter gives the real average.

The page multiplies the power in watts by the hours per day and divides by 1,000 to get kilowatt-hours per day. It multiplies that by the number of days for the period's energy and by your price per kWh for the cost; the yearly figure uses 365 days. Taxes and fixed monthly charges on your bill are not included.