This calculator calculates the cost of electricity in running electrical appliances and equipment. The required values are as given in the table. The power rating (watts) is usually given in the back label of appliances. The energy rate (cents/kw-hr) can be found in the electricity bill. This calculator is useful for estimating energy cost and also for making sense of your electricity bill. There are also gadgets out there that can be attached to your electrical appliance and give you a running total of usage time.