AC Electricity Cost Calculator

The AC Electricity Cost Calculator estimates how much your air conditioner adds to the monthly electricity bill, based on tonnage, BEE star rating, daily usage hours, and your state's tariff. Air conditioning is usually the single largest line item on an Indian household's summer power bill — often more than the fridge, geyser, fans and lights combined — so knowing the number before the bill arrives helps you choose the right unit, set a sensible thermostat, and decide whether a higher star rating is worth the premium. It is built for anyone shopping for a new split AC, comparing 3-star versus 5-star models in a Croma or Reliance Digital showroom, or simply trying to understand why the April-to-June electricity bill jumped.

The formula

Running cost follows one straightforward chain. First the tool finds your unit's hourly consumption in kilowatt-hours (kWh, the "units" on your bill), then multiplies through to daily, monthly and yearly figures:

Monthly cost = kWh/hour × hours/day × 30 × tariff

Worked through: a 1.5-ton 3-star inverter split draws roughly 1.30 kWh per hour. Run it 8 hours a day, and that is 1.30 × 8 = 10.4 units per day, or about 312 units a month. At a tariff of ₹8 per unit, the monthly running cost is 312 × ₹8 = ₹2,496. The yearly figure then depends on how many months you actually run the AC — most Indian households run it 5 to 8 months, so at 6 months that example works out to roughly ₹14,976 a year. The kWh/hour figure for each tonnage and star combination comes from the BEE Energy Star Label database (Indian Standard IS 1391) and manufacturer datasheets from Voltas, Daikin, LG, Samsung and Hitachi. It is the effective consumption at a realistic 70-80 percent compressor duty cycle — the number that actually shows up on your bill, not the lab-perfect rated figure.

Tonnage, ISEER and star rating

Tonnage is the cooling capacity: a 1-ton AC suits a small bedroom (up to about 120 sq ft), 1.5-ton is the most popular size for a standard 150-180 sq ft room, and 2-ton suits large halls or rooms with heavy sun. Oversizing wastes money; undersizing makes the compressor run flat out and never reach the setpoint. The BEE star rating is built on ISEER (Indian Seasonal Energy Efficiency Ratio) — total cooling delivered divided by total energy consumed across a full cooling season. Higher ISEER means lower running cost for the same comfort. A 5-star AC consumes about 17 percent less power than a 3-star, and about 35 percent less than a 1-star, for the same tonnage.

Star rating and payback

The MRP premium for a 5-star over a 3-star averages about ₹8,000 for a 1.5T inverter split. For an 8-hour/day user at ₹8/unit running the AC 6 months a year, the lower running cost claws that premium back in roughly 3 years — well within the unit's 10-12 year service life, after which it is pure saving. Heavy users in high-tariff states such as Maharashtra or Karnataka (₹9-11/unit) hit payback even faster, while a light user (2-3 hours a day, 3 months a year) on a subsidised slab may take 8-10 years, in which case a 3-star is the smarter buy. The star-rating comparison table above does this math for all five ratings at your exact usage so you can see the trade-off at a glance.

Tips to cut your AC bill

Set the thermostat to 24°C rather than 18-20°C — the BEE and the Ministry of Power both recommend 24°C as the comfort-and-efficiency sweet spot. Run a ceiling fan alongside the AC so you can raise the setpoint a degree or two without losing comfort. Use the sleep timer to switch off an hour or two after you doze off, clean the filter monthly so the compressor is not fighting choked airflow, and draw curtains against direct afternoon sun.

Why your actual bill may differ — common mistakes

The model assumes a 24-26°C setpoint, a clean filter, average insulation, and an inverter compressor (the BEE standard since 2018). The biggest real-world swing is the thermostat: each 1°C cooler than 24 raises consumption by roughly 6 percent, so a 20°C setting can cost about a quarter more than 24°C. Other common mistakes are forgetting that older non-inverter ACs and window units consume 15-25 percent more than equivalent split ACs, and entering the rated peak draw instead of effective consumption. For an exact figure for your specific unit, read the annual energy consumption printed on the BEE label and divide by 1600 (the test-cycle hours used for the rating) to get its kWh per hour.