Air-conditioner cost depends on input power, runtime, thermostat setting, weather, room heat gain, maintenance, and electricity tariff. A simple estimate is a starting range, not a guaranteed bill.
Upper-bound formula
Seasonal kWh = input kW × hours per day × days used
Cost = seasonal kWh × tariff
Worked example
An AC drawing 1.5 kW runs 6 hours a day for 120 days. The full-power estimate is 1.5 × 6 × 120 = 1,080 kWh. At ₹8 per kWh, that is ₹8,640.
Add a duty-cycle scenario
Compressors often cycle or modulate after the room reaches temperature. If average draw is estimated at 70% of full input, energy becomes 756 kWh and cost becomes ₹6,048. Use measured consumption when available because duty cycle varies significantly.
Inputs that improve accuracy
- Electrical input power, not only cooling capacity.
- Expected hours by month.
- Room size, insulation, sun exposure, and occupancy.
- Thermostat setting and outdoor temperature.
- Local slab or time-of-use tariff.
The Unit Converter can standardise watts and kilowatts. Use the Percentage Calculator to compare measured use before and after efficiency changes.
Frequently asked questions
Is cooling capacity the same as electrical input?
No. Use the rated or measured electrical input for energy-cost calculations.
Does a higher star rating guarantee my bill?
No. Efficiency helps, but climate, sizing, settings, and runtime still matter.
How can I validate the estimate?
Compare utility readings across similar-weather periods or use a compatible energy monitor.
Compare full-power and measured-use scenarios
For the example AC, a full-power estimate is 1,080 kWh. At a 50%, 70% and 90% average duty factor, seasonal consumption would be 540, 756 and 972 kWh. At ₹8 per kWh, that range is ₹4,320 to ₹7,776. It is more honest than presenting one operating cost as certain.
Use comparable weather periods when validating savings. A lower bill after replacement may come from milder weather or fewer occupied days rather than efficiency alone. Clean filters, correct sizing and sensible thermostat settings can affect actual consumption and comfort.
Quick verification
Compare the estimate with two utility readings taken across similar weather and occupancy. Subtract a reasonable non-AC baseline, then divide the remaining kWh by operating hours. This measured average can replace the assumed duty factor in the next calculation.