Here's a pretty helpful chart I found: Electric Power Monthly - Average Retail Price of Electricity to Ultimate Customers by End-Use Sector, by State Average electricity prices (per kWh) for every state. So the electricity cost of your lights for one grow cycle will be: Light wattage * %of day your lights are on * cost of electricity * 24h/day * 30 days/month So lets say you have 1000W of lights for both veg and flower, and that you do 18/6 in veg and 12/12 in flower Say you veg for 8 weeks (2 months) and flower for 8 weeks (just for some practice numbers) Now lets say you live in a residential area in Colorado, where prices are 10.5 cents / kWh so... 1000W = 1kW... 1 kW * (18/24) * $0.105 * 24h/day * 30day/month * 2 month = $113.4 total cost of vegetative cycle for 2 months = $56.7/month 1 kW * (12/24) * $0.105 * 24h/day * 30day/month * 2 month = $75.6 total cost of vegetative cycle for 2 months = $37.8/month so your total cost of this grow for electricity is 113.4+75.6 = $189 not assuming everyone is dumb and can't do math but i found the link and thought i'd make it a complete idea. This doesn't include the electricity cost of running your ventilation... just find the wattage of those and follow a similar procedure and add it in. Also doesn't include cost of growth materials obviously. Just thought it might be useful to anyone trying to plan on costs or perhaps plan their electricity bill out to hide anything suspicious...