For those of you that really want to know what each device you have is costing you per/month on your electric bill, you might consider buying a "Kill-A-Watt" Meter.
$20.28 at Home Depot
It will allow you to track EXACTLY what each of your devices costs you.
For example, I just hooked it up to my two 430 watt HPS lights in my flowering room. Each 12 hours, it tells me to the decimal point how much electricity was used and to the minute, how much time was involved.
By doing a bit of math, I've found that those two 430 watt HPS cost me $1.30 for each day they are on for 12 hours.
That meter is worth its weight in gold, in peace of mind.
Plus, its just fun to play with...hehe :hubba:
The way I calculate my REAL electric bill costs per/kwh is to use the entire amount of the bill, including taxes for this, taxes for that, this charge, that charge.....it's all part of your bill.
The supposed kwh rating is nonsense after you add all that other stuff.
It knocks mine from ten cents per/kwh, all the way to 13 cents.
I use the past years costs to determine the total and then divide by the number of months for a one month average. For me, that average is 13 cents per/kilowatt.
Get that meter! It's priced great and is one hell of a tool!
Plug and Play!