How to calculate an electricity bill
Calculate electricity units from watts and hours, estimate the energy charge and understand why an Indian electricity bill may include other charges.
What is one electricity unit?
One electricity unit is one kilowatt-hour, written as 1 kWh. A 1,000-watt appliance running for one hour uses 1 kWh. A 100-watt appliance running for ten hours also uses 1 kWh.
Use the basic formula
Monthly units = watts × quantity × hours used per day × days used ÷ 1,000. For an appliance that switches on and off, also multiply by a realistic operating factor.
Estimate the energy charge
Energy charge = monthly units × your electricity rate per kWh. Use the rate or slab details from your own bill. The example rate in a calculator is not a universal Indian tariff.
Why the final bill may be different
A bill may also include fixed charges, slab pricing, fuel adjustments, duties, taxes or subsidies. Appliance cycling, voltage, weather and condition can change actual use. Compare the estimate with several real bills.