Here is everything you've always wanted to know, but were afraid to ask about power use.
Later on we'll cover how to measure the exact amount of electricity something uses. But the shortcut is to just look at the label! Nearly everything you can plug into the wall has a label that says how much electricity it uses. (It may be printed directly into the plastic or metal.) You may have to hunt for the label. It's often located on the bottom or side of the device, or possibly where the power cord enters the unit. If the device is powered with an AC/DC adapter, the electrical rating is usually listed on the adapter itself.
If the label only gives the number of amps and not the number of watts, then just multiply the amps by 120 to get the number of watts. (Amps x Volts = Watts, and most U.S. electricity is 120 volts. So a hot plate that uses 6 amps uses 6 x 120 = 720 watts...
from lanux128 and www.donationcoder.com/forum/index.php?topic=7211
Kenneth P. Reeder, Ph.D.
Jacksonville, North Carolina 28546