How can you tell how much a appliance would cost to run monthly?

Question

Example a 250 watt eletric heater runs 9 hours a day for 30 days.
How much would this cost to run monthly?

Answer 1

Well the watt rating is made in watthours so for the example you provided each hour of operation the device uses that 250watts then multipy by #of hours used per day which gives you 2250watthrs times the #of days = 67500 then divide by 1000 to convert it to kilowatts and you get 67.5kwh. then you multiply by the amt the utility charges per kwh let say its $0.20per kwh gives you the cost per month of $13.50
you can also get devices that plug the apliance into like the kill-a-watt which does the figuring for you.

Answer 2

A new appliance would have that information on it. Perhaps there is a formula there too.