Actually I use Canadian funds it cost about $50 to $56 canadian dollars to run for one month on 12/12 cycle 18/6 would cost me probably around $70 to $75,it's not a big difference on your light bill either! I only use the hps for 12/12 14/12. don't know what that would be in american?....tip of the day,if you want to keep the electric bill down without a 56 dollar increase just start being more conservative with your utilit'es,if your not watching tv shut it off,don't leave bathroom fan running all day!,keep the lights off when your not in the room,just keep an eye on those things and the bill will balance out youl'l be surprised....