How we worked it out
Updated as you change the numbers.
- kWh per day = watts × hours ÷ 1,000. Cost = kWh × rate.
Method and assumptions
A kilowatt-hour is 1,000 watts for one hour. Appliances with thermostats or motors (fridges, heaters, AC) don’t draw full power all the time, so their real use is lower than watts × hours; a plug-in energy meter gives the true figure.
Questions
How much does a 1,500 W heater cost to run 4 hours a day at 17¢?
About $1.02 a day, $31 a month.
Sources
Method and figures checked on . Every worked answer on this page is covered by an automated test. Found a mistake? Tell us.