AC Running Cost Calculator: How Much Does AC Cost per Month?

Enter the BTU rating, efficiency, hours of use and your electricity rate. See kWh and cost, plus a non-inverter vs inverter comparison.

Free, no sign-upInstant resultsUpdated October 2026
BTU/h
BTU/Wh
On the yellow EnergyGuide label. Window units: CEER 10–12; mini-splits: SEER2 17–30.
h
%
Share of full power the compressor averages: 50–70% for a well-sized unit.
$/kWh
Cost per month
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How we calculated this

    For estimating and educational purposes only. Results are approximate and are not a substitute for a licensed professional, the manufacturer's instructions or your local code. Disclaimer

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    From BTU and SEER2 to kWh

    SEER2 and EER2 are BTU of cooling per watt-hour of electricity. Divide the capacity by the efficiency to get the power draw at full output, then multiply by the hours and the average load.

    Power (kW) = BTU/h ÷ SEER2 ÷ 1000 kWh/month = power × average load × hours/day × days Cost/month = kWh × price per kWh

    Worked example

    A 12,000 BTU mini-split with SEER2 15: 12,000 ÷ 15 = 800 W at full output. At a 60% average load, 8 hours a day for 30 days: 0.8 × 0.6 × 8 × 30 = 115.2 kWh. At $0.17/kWh that is $19.58 per month.

    Inverter vs non-inverter

    A non-inverter unit cycles on and off at full power; an inverter slows its compressor to match the load and gets much higher seasonal efficiency. The calculator shows the same use with a typical window unit (EER about 11) and a typical inverter mini-split (SEER2 about 20).

    Frequently asked questions

    How much does it cost to run a 12,000 BTU AC?

    About $0.05–$0.15 per hour depending on efficiency and load at $0.17/kWh, or $15–$35 a month at 8 hours a day.

    Does an inverter AC save money?

    Usually yes: at part load an inverter uses far less power than a unit that cycles on and off, which is why mini-splits have SEER2 ratings of 17–30.