How much does your AC cost to run?
Start with electrical input watts. Cooling capacity in tons is not electrical power.
Rates as per TNPDCL, October 2026A useful starting estimate
For a 1.5 ton inverter AC example, use 1,350 W, eight hours per day, 30 days per month and 60% compressor on-time. This gives 194.4 kWh per month, or 388.8 kWh over two months.
If it were the only load, rounded use would be 389 units and the estimated bill would be Rs. 888. In a real home, add fans, lights and other appliances before calculating the bill.
Why compressor on-time matters
An AC does not necessarily draw its input power continuously. Inverter units vary their output. On-time is a simplified way to estimate the average load. Room size, outdoor heat, insulation, set temperature and servicing can change the result.
The 60% value is an editable assumption, not a measurement. Try a lower and higher value to see the range.
Using a BEE label
If you enter annual kWh from the label, this calculator uses annual kWh ÷ 12 for a monthly average. It does not apply your daily hours or on-time again. The label is based on test conditions, which can differ from your use.
See the BEE guide to energy labels. Do not infer exact watts from the star rating alone.
Check the total household bill
If your total is near 500 units, a small reduction can keep the 200-unit free allowance. Compare the bill before and after changing AC usage to see the whole-home saving.
Use the calculator ↗