AC Electricity Cost Calculator
Estimate how much electricity your air conditioner uses and what it adds to your bill each month.
Quick answer
A 1,200 W window AC running 8 hours a day with the compressor on 70% of the time uses about 6.7 kWh — roughly $1.14 a day or $34 a month at $0.17/kWh. A ceiling fan costs about a penny an hour by comparison.
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- Energy
- Updated October 2026
Cost per month (30 days)
$34.27
- Cost per day
- $1.14
- Cost per year
- $416.98
- Cost per hour of use
- $0.14
- Energy per day
- 6.72 kWh
- Energy per month
- 201.6 kWh
Show the working
- 1,200 W × 8 h × 70% × 1 ÷ 1000 = 6.72 kWh/day
- 6.72 kWh × $0.17 = $1.14 per day
About the AC Electricity Cost calculator
Air conditioners are usually the biggest summer electricity load. Typical power draw while the compressor runs: small window units 500–900 W, 1–1.5 ton split units 1,000–1,800 W, and central systems 3,000–5,000 W. Check the rating plate for “rated input power” or “cooling power input”.
The compressor cycles off once the room reaches the set temperature, so the average draw is lower than the label. 60–80% is a fair starting point on hot days; inverter models in mild weather can average much less. The default here is a 1,200 W split unit at 70% load for 8 hours.
Each degree you raise the thermostat typically trims a few percent off cooling energy. Clean filters, shaded outdoor units and closed curtains during the afternoon all reduce how hard the compressor works.
How to use it
- Enter your AC’s input power in watts (not the BTU or cooling capacity).
- Enter hours of use per day.
- Keep 70% load for a hot day, or lower it for an inverter unit in mild weather.
- Enter your price per kWh.
The formula
Monthly cost = Watts × Hours × Load ÷ 1000 × 30 × Price
- BTU ratings describe cooling output, not electricity use. If you only know the EER, input watts ≈ BTU ÷ EER.
Worked example
A 1.5 ton split AC
- 1,500 W × 8 h × 70% = 8.4 kWh per day.
- At $0.17/kWh: about $1.43 per day.
- About $42.84 over a 30-day month.
Frequently asked questions
How many watts does a 1.5 ton AC use?
Usually 1,300–1,800 W while the compressor runs, depending on efficiency. Inverter models draw less on average because they slow the compressor rather than switching it off and on.
Is it cheaper to leave the AC on all day?
Usually not. Raising the set point or switching off while you’re out uses less energy overall than holding a low temperature in an empty home, even though cooling back down takes some extra work.
Does a higher star or SEER rating really save money?
Yes — a more efficient unit delivers the same cooling for fewer watts. The saving is largest in hot climates where the AC runs many hours a day.
Results are estimates for planning — check critical figures with a professional or the official source.
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