How Much Does a Mini Split Cost to Run? (2026 Data)

A 900-watt mini-split at half duty cycle draws 0.45 kWh for every hour the system runs, which costs about 8 cents an hour at the US average rate from the EIA Electric Power Monthly. That half duty cycle is the key number. Once the room hits temperature, the inverter compressor modulates speed to hold a setpoint, so it rarely draws the full 900 watts after the first few minutes of cooling or heating.

As primary heating or cooling at 12 hours a day, the system uses about 162 kWh a month and costs $29. Supplemental use in a bedroom at six hours drops to 81 kWh and $15. Light shoulder-season cycling at four hours runs about 54 kWh and $10. Over a full year as primary HVAC at 12 hours a day, a single-zone mini-split adds about $351 to the annual electricity. Used for cooling only across a five-month summer, that drops to $146.

Mini-splits are sized by BTU output, and the nameplate wattage scales with it. At 12 hours a day with the same half duty cycle, the monthly cost by size runs: a 9,000 BTU unit at about 750 watts costs $24. A 12,000 BTU unit at about 1,000 watts costs $32. An 18,000 BTU unit at 1,500 watts costs $49. A 24,000 BTU unit at 2,000 watts costs $65. The jump from the smallest to the largest common single-zone size is $41 a month, nearly triple.

Brand differences within the same BTU class are much smaller. Among 9,000 BTU single-zone units, a Mitsubishi MSZ-FS09NA at 700 watts costs about $23 a month, an LG LS090HEV1 at 750 watts costs $24, and a Daikin FTXS09LVJU at 800 watts costs $26. The full brand gap is $3 a month. Picking the right size for the room matters far more than picking the right nameplate on the shelf.

Multi-zone systems with three or four indoor heads share one outdoor compressor. When all heads run simultaneously, the outdoor unit draws 2,000 to 2,400 watts, putting the whole system between $65 and $78 a month at 12 hours. Each head that cycles off reduces the load because the inverter scales down to match the remaining demand.

Most air conditioners use a single-speed compressor that runs at full power until the thermostat clicks off, then sits idle until the room warms up again. A mini-split inverter compressor works differently. It ramps up fast during the initial pull-down, then throttles back to a fraction of its rated wattage to hold the target temperature. The system spends most of its running hours at low speed, which is why a 900-watt nameplate translates to roughly 450 watts of average consumption over a day.

Higher SEER2 ratings reflect this efficiency. A unit rated SEER2 20 or above spends more of its time in the low-draw cruising range than a unit rated SEER2 15, even at the same nameplate wattage. The rating captures the seasonal average, not the peak, so a higher number means a lower real-world duty cycle and a lower monthly bill for the same cooling output.

All three cool a space, but they draw very different amounts of power doing it. Per hour at half duty cycle: a mini-split costs about 8 cents, a window AC at 1,200 watts costs about 11 cents, and a central AC at 3,500 watts costs about 32 cents. Over a month at 12 hours a day, that spreads to $29, $39, and $114.

The mini-split costs 26 percent less than the window unit and 75 percent less than central air on a per-zone basis. Part of that gap is the inverter advantage: the mini-split modulates while the window unit cycles at full power. Part of it is scope: the mini-split cools one zone while central air cools the whole house. Three 9,000 BTU mini-splits covering three zones run about $73 combined, still 36 percent less than the single central system at $114.

Per-hour numbers are in the air conditioner cost per hour breakdown. A full summer of central AC is tallied in the summer AC cost guide. If the choice is between a fan and any air conditioner, the fan versus AC comparison covers that math.

A 900-watt mini-split at half duty cycle and 12 hours a day uses 162 kWh a month wherever it sits. The only variable is the state rate:

Louisiana (12.44¢/kWh): $20. Texas (14.80¢/kWh): $24. US average (18.05¢/kWh): $29. New York (24¢/kWh): $39. California (33.75¢/kWh): $55. Hawaii (39.89¢/kWh): $65.

Hawaii pays 3.2 times what Louisiana does for the same unit running the same hours. In Hawaii, a 24,000 BTU unit as primary HVAC climbs to about $144 a month. Every state's current residential rate is in the state rates guide.

The three cheapest levers are all free. Run the system in Auto so the inverter picks its speed. Clean the indoor filters every two weeks during heavy use, because clogged filters restrict airflow and force the compressor to work harder, which pulls efficiency below the SEER2 rating the manufacturer tested. And condition only the rooms you're in, which is the whole point of a zoned system. Each occupied room is its own load; each empty room with the head turned off is money not spent.

These numbers use a 900-watt single-zone unit at half duty cycle. Your unit's wattage, how many hours it runs, and your state rate all move the result. Plug your system's draw and your state into the mini-split calculator for a monthly and yearly figure. If the mini-split install isn't in the budget, the portable AC cost breakdown covers another single-room cooling option.