Question: how to calculate electricity per unit?
Answer: for instance, If you switched ON a 1000 watt bulb for 1 hour, It mean you consumed 1000 watts for an hour i.e. (1000 watts for 1 hour = 1kWh = 1 unit of Energy). So if the rate of unit is $5 , then you will pay 5 Dollars as a bill for your bulb which consumed 1kWh = 1 unit of electricity.