Formula
kWh = watts × hours per day × days ÷ 1,000. Multiply by your rate per kWh. The US average residential rate is around 17 cents per kWh, but it varies a lot by state; check your bill.
Example
A 1,500 W space heater used 2 hours a day uses 90 kWh a month. At $0.17 per kWh, it costs about $15.30 a month.
Frequently asked questions
Where do I find the wattage?
On the label or in the manual. For fridges, use the yearly kWh on the Energy Guide label.
See also
Results are estimates for information only and are not financial, legal or medical advice. Rates, taxes and fees vary — confirm with a professional or your lender.