Question: how do you calculate electricity usage?
Answer: Watts (electric usage rating of your items, 1 kilowatt is 1000 watts) ...  Watts/1000 = kilowatts or kW. ...  Hours used in month (use an average) ...  Kilowatts x Hours = Kilowatt Hours or kWh. ...  Electricity price (in pence per kWh - enter the cost you pay)