This topic sent me to my calculator and it appears my small homemade set up costs me about $25 per month. It is an easy calculation; you pay by KWH (kilowatt hour). Add up the wattage of all the devices that you use, including incubators, brooders etc. (remember that the incubator is not always pulling power) Then multiply that by .72 (24 hrs x 30 days divided by 1000). This is the total KWH that youre set up uses. Multiply that by the rate you pay on your utility bill and you have the cost. My total wattage is 220, times .72 is 158.4 KWH, and times my rate of $0.1568 equals $24.84 per month. The distance from your meter and extension cords have some bearing on the cost, but this should give you a good approximation. Hope someone finds this useful.