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Electricity Cost Calculator: Units & Energy Charges
Estimate energy units and cost for multiple loads. Results include the values and assumptions used.
Formula and worked example
Daily kWh = Σ[(watts / 1000) × quantity × hours per day]
Period kWh = daily kWh × days
Energy charge = period kWh × your flat ₹/kWh rate.
Period kWh = daily kWh × days
Energy charge = period kWh × your flat ₹/kWh rate.
How to use the calculation
One electricity unit is one kWh. Enter electrical input power and the time each appliance operates. For a cycling appliance such as an air conditioner, use measured average input power or equivalent full-power operating hours for a more useful estimate.
Worked example
An illustrative 1,500 W load for 8 hours/day plus two 70 W fans for 8 hours/day uses 13.12 kWh/day. Over 30 days, that is 393.6 kWh. At an entered ₹8/kWh flat rate, energy charges are ₹3,148.80.
Common questions
Why can the utility bill differ from this estimate?
Actual bills may use slabs, fixed charges, demand charges, taxes or subsidies. This tool applies only the flat rate you enter to estimated energy use.
Can I enter motor shaft-output kW directly?
Use electrical input power here. A motor output rating does not include its losses; the Motor Current calculator can show the input-power equivalent when efficiency is known.
Can I calculate a load that runs for part of an hour?
Yes. For example, 0.5 hours represents 30 minutes. A quantity is a whole number of identical loads; separate different appliances into their own rows.
Related electrical guides
More electrical calculators
Formula references
Formula review: 31 October 2026. Examples are illustrative; use your actual equipment and project data.
