ManualHarbor

How Much Does It Cost to Run a Mini Split?

Updated October 9, 2026

A 12,000 Btu/h (1-ton) single-zone mini-split rated at 13.0 EER2, the median for that size among ENERGY STAR-certified listings, draws about 0.92 kW at full cooling output. At the U.S. average residential price of 18.19¢/kWh, that's about 17 cents an hour. Inverter-driven mini-splits spend most of their time running below full speed, so treat that as a ceiling rather than a typical hour. Over a season, the example worked below comes to roughly $29–$60 a year for cooling and $213–$310 for heating, using hours for Chicago and Belleville, Illinois, from a state energy-efficiency manual.

Cost per hour at rated power

Three formulas turn ratings into dollars:

  • Cooling input (kW) = cooling capacity (Btu/h) ÷ EER2 ÷ 1,000
  • Heating input (kW) = heat output (Btu/h) ÷ (COP × 3,412), because 1 kWh equals 3,412 Btu
  • Cost per hour = input kW × your electricity price ($/kWh)

ENERGY STAR's certified heat pump data lists EER2, SEER2 and HSPF2 for each mini-split it certifies, and heating output and COP at 5°F for nearly all of them. Here's what the medians look like by size:

  • 9,000 Btu/h (2,198) — Median EER2: 13.5; Cooling draw at full output: 0.67 kW; Cooling cost per hour: $0.12; Median 5°F heat output and COP: 8,300 Btu/h at COP 1.995; Heating draw at 5°F: 1.22 kW; Heating cost per hour at 5°F: $0.22
  • 12,000 Btu/h (2,377) — Median EER2: 13.0; Cooling draw at full output: 0.92 kW; Cooling cost per hour: $0.17; Median 5°F heat output and COP: 10,000 Btu/h at COP 1.95; Heating draw at 5°F: 1.50 kW; Heating cost per hour at 5°F: $0.27
  • 18,000 Btu/h (2,066) — Median EER2: 12.5; Cooling draw at full output: 1.44 kW; Cooling cost per hour: $0.26; Median 5°F heat output and COP: 13,800 Btu/h at COP 2.0; Heating draw at 5°F: 2.02 kW; Heating cost per hour at 5°F: $0.37
  • 24,000 Btu/h (1,628) — Median EER2: 12.25; Cooling draw at full output: 1.96 kW; Cooling cost per hour: $0.36; Median 5°F heat output and COP: 20,100 Btu/h at COP 2.0; Heating draw at 5°F: 2.95 kW; Heating cost per hour at 5°F: $0.54

Medians calculated by ManualHarbor from ENERGY STAR's "Mini or Multi Split" listings at each exact capacity, accessed October 10, 2026. Costs at 18.19¢/kWh (EIA, January–July 2026). Each column's median is calculated separately, so a row doesn't describe one particular model.

Example (12,000 Btu/h, cooling): 12,000 ÷ 13.0 = 923 W, or 0.923 kW. Then 0.923 kW × $0.1819 = $0.17 per hour at full output.

Example (12,000 Btu/h, heating at 5°F): 10,000 Btu/h ÷ (1.95 × 3,412) = 1.50 kW, which costs $0.27 per hour. Electric baseboard heat has a COP of 1, so it would need 2.93 kW for the same 10,000 Btu/h, about $0.53 per hour.

To check a specific system, look up the exact outdoor and indoor model combination in our mini-split heat pump listings or its AHRI certificate. You can also browse certified models by brand, such as Mitsubishi Electric heat pumps, Daikin heat pumps or the Fujitsu brand page. Ratings belong to a specific pairing, so don't apply one model's numbers to another.

Why rated power overstates a typical hour: inverter part-load

Every one of the 17,854 mini- and multi-split listings in ENERGY STAR's dataset reports a "continuously variable" compressor. The DOE-funded Building America Solution Center explains that these inverter compressors can ramp down to as little as 10% of rated capacity. A conventional single-stage system, by contrast, can only run at full output and has to cycle on and off.

Running slower usually means running more efficiently. In a DOE Building America field study of ductless heat pumps in the Northeast, one unit recovering from a thermostat setback put out 13,000 Btu/h at a COP of 2.15. As the room approached the set point, it slowed to 6,500 Btu/h at a COP near 3.0.

  • Recovering from setback (high speed) — Heat output: 13,000 Btu/h; COP: 2.15; Electrical draw: 1.77 kW; Cost per hour at 18.19¢/kWh: $0.32
  • Modulated down near set point — Heat output: 6,500 Btu/h; COP: 3.0; Electrical draw: 0.64 kW; Cost per hour at 18.19¢/kWh: $0.12

Draw and cost calculated by ManualHarbor: output ÷ (COP × 3,412).

Half the heat took only about 36% of the power. The same study shows the limit of this effect. When the load drops below the unit's minimum output, it starts cycling, and efficiency falls. In a very well-insulated house where a 1-ton unit served a design load of about 6,000 Btu/h, daily COPs were near 2.5 around 40°F outside when the unit could modulate. Above 50°F, frequent cycling pulled COPs down to near 1.5. That's why the Solution Center warns that oversized units short-cycle and waste energy, and recommends an ACCA Manual J load calculation for each zone.

Seasonal cost with SEER2 and HSPF2

Use the seasonal ratings with an estimate of equivalent full-load hours for your area:

  • Cooling kWh = cooling capacity (Btu/h) × full-load cooling hours ÷ SEER2 ÷ 1,000
  • Heating kWh = heating capacity (Btu/h) × full-load heating hours ÷ HSPF2 ÷ 1,000

Example: a 12,000 Btu/h single-zone unit with the 12,000 Btu/h medians of 23.0 SEER2 and 10.0 HSPF2, a heating capacity of 12,000 Btu/h, and electricity at 18.19¢/kWh. The full-load hours come from the Illinois Technical Reference Manual's ductless heat pump measure.

  • Rockford, IL — Cooling hours: 323; Cooling kWh and cost: 169 kWh, $31; Heating hours: 1,520; Heating kWh and cost: 1,824 kWh, $332; Season total: $362
  • Chicago, IL — Cooling hours: 308; Cooling kWh and cost: 161 kWh, $29; Heating hours: 1,421; Heating kWh and cost: 1,705 kWh, $310; Season total: $339
  • Belleville, IL — Cooling hours: 629; Cooling kWh and cost: 328 kWh, $60; Heating hours: 977; Heating kWh and cost: 1,172 kWh, $213; Season total: $273

Calculations by ManualHarbor. Hours from the 2019 Illinois TRM v7.0, which based them on metering of multifamily units in weatherized buildings. For heating, the TRM notes that a mini-split in a single-family home, especially one serving a single room, may be used more sporadically, and that unweatherized buildings may need longer hours. At Illinois's own January–July 2026 average of 19.22¢/kWh, every cost would be about 5.7% higher.

Two things stand out. First, in a heating climate, heating dominates the bill: Chicago's hours are 1,421 for heating versus 308 for cooling. Second, the heat pump is far cheaper than resistance heat for the same job. Electric baseboard heat would need about 4,998 kWh (about $909) for Chicago's heating hours in this example. ENERGY STAR says mini-splits can use up to 60% less energy than standard electric radiators. The roughly 66% gap in this example comes from rated efficiency, and field results can fall short of ratings.

Heating vs. cooling: what changes the cost

  • Outdoor temperature: to earn ENERGY STAR's cold-climate designation, a heat pump needs a COP of at least 1.75 at 5°F and must keep at least 70% of its 47°F heating capacity at 5°F. ENERGY STAR suggests pairing cold-climate units with a backup heat source for the most efficient heating at very low temperatures.
  • Field conditions: in the Building America study, overall heating COPs for the 2013–2014 monitoring period ranged from 1.1 to 2.3 across seven ductless units. The researchers linked the spread to low indoor airflow, poor outdoor-unit placement, high return-air temperatures, thermostat setbacks and occupants holding the fan on a low speed.
  • Cooling climate: in hot regions, the cooling side carries more weight, and SEER2 matters more than HSPF2.

Single-zone vs. multi-zone

ENERGY STAR's specification separates two layouts that share one outdoor unit. A multi-split has indoor units that run independently on separate thermostats. A multi-head mini-split has indoor units that operate together from one thermostat. Running costs behave differently from a set of separate single-zone systems:

  • Ratings depend on the pairing. In ENERGY STAR's dataset, 3,548 of 7,602 mini/multi-split outdoor model numbers appear with more than one SEER2 value. Each listing is a specific combination, and the rating changes with the indoor units connected. Use the rating for your exact combination.
  • Mixed modes cost efficiency. The Building America Solution Center warns that if some heads call for heating while others call for cooling, the outdoor unit switches back and forth, which greatly reduces efficiency.
  • Turning off heads may not save much. The Solution Center says savings can range from modest to negative if the remaining load falls below the outdoor unit's minimum output and it starts cycling, and some refrigerant still flows through idle heads.
  • Head count: the Solution Center says connecting more than three indoor units to one outdoor unit is generally not recommended, though some models allow up to eight. It suggests a separate outdoor unit for a room that is often used on its own.

To estimate a multi-zone system's cost, apply the seasonal formula to the outdoor unit's certified combined rating and capacity, not to each head separately.

Keeping mini-split running costs down

  • Size each zone correctly. Get a Manual J load calculation so the unit can modulate instead of short-cycling.
  • Leave the fan on auto. In the Building America study, units held on a low fan speed delivered less heat and lower COPs.
  • Avoid deep setbacks in heating. ENERGY STAR recommends a steady temperature for heat pumps, and the field data showed lower efficiency during high-speed setback recovery.
  • Keep filters and the outdoor unit clear. The Solution Center notes that washable mesh filters may need cleaning about every two weeks. Follow your manufacturer's schedule.
  • Use a licensed technician for refrigerant and electrical work. Mini-splits carry pressurized refrigerant and line-voltage wiring.

FAQ

How much does it cost to run a mini split 24 hours a day?

At full cooling output, the 12,000 Btu/h example (0.923 kW) would use about 22.2 kWh a day, about $4.03 at 18.19¢/kWh. Because inverter units slow down once the room is at temperature, actual daily use is usually lower.

Is a mini split cheaper to run than central air?

Often, because there are no ducts to leak and many mini-splits carry high ratings. The 12,000 Btu/h median is 23.0 SEER2, compared with the 13.4 SEER2 federal minimum for split central ACs. The Building America Solution Center notes that duct losses can exceed 30% of heating and cooling energy when ducts run through unconditioned space. Actual savings depend on sizing, installation and how you use the zones.

Should I turn my mini split off when I leave?

In heating season, ENERGY STAR recommends holding a steady temperature on heat pumps. Field data showed that recovery after a setback runs at high speed and lower efficiency. In cooling season, DOE's general advice is to raise the thermostat when you're asleep or away. Check your manufacturer's guidance as well.

Is a mini split cheaper than electric baseboard heat?

Yes, for the same heat. Baseboard heat has a COP of 1, while ENERGY STAR cold-climate mini-splits must reach at least 1.75 even at 5°F. In the 5°F example above, the heat pump costs $0.27 an hour versus about $0.53 for baseboard.

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