How Much Does a Mini Split Cost to Run?
Updated July 6, 2026
Just want the number? Use the energy cost calculator.
A 12,000 BTU (one ton) mini split draws about 1,000 to 1,200 watts while it is cooling, which costs roughly 17 to 20 cents per hour at the U.S. average electricity rate. Run it 8 hours a day and you are looking at about 40 to 50 dollars a month. The exact figure depends on the head size, how many hours it runs, and your local rate, but the formula is the same for every unit.
The watts to dollars formula
Electricity is billed in kilowatt-hours, so the cost has two steps.
- Convert watts to kilowatts. A 1,100 watt head is 1.1 kilowatts.
- Multiply kilowatts by hours, then by your rate. At 17 cents per kWh, 1.1 kilowatts running for one hour costs about 19 cents.
The U.S. average residential electricity rate is about 17 cents per kWh, according to the U.S. Energy Information Administration. Your bill may be higher or lower depending on your state and utility.
Cost by common head size
Mini split indoor heads are sold in a handful of standard capacities. Here is what each one typically draws and costs at the 17 cent average rate:
| Head size | Typical draw | Cost per hour | Monthly (8 hrs/day) |
|---|---|---|---|
| 9,000 BTU | about 800 W | about $0.14 | about $33 |
| 12,000 BTU | about 1,100 W | about $0.19 | about $46 |
| 18,000 BTU | about 1,600 W | about $0.27 | about $65 |
| 24,000 BTU | about 2,100 W | about $0.36 | about $87 |
These are typical draws for an inverter-driven mini split running at or near full output on a hot day. Real-world usage is often lower. Modern mini splits use variable-speed compressors that throttle down once a room reaches the target temperature, so the actual average wattage across a full day is meaningfully below the rated peak, often well under half of it.
Heating mode costs less per BTU
Mini splits are heat pumps, not resistance heaters. In heating mode they move heat from the outdoor air into your home rather than generating it from scratch, so they deliver more BTU of warmth per watt than a space heater or electric baseboard.
A well-specified heat pump mini split can produce 2 to 3 units of heat for every unit of electricity it consumes, measured as a coefficient of performance (COP) of 2 to 3. That means your 12,000 BTU head might draw only 500 to 700 watts on a mild winter day while still delivering full warmth, which cuts the hourly cost roughly in half compared to cooling season. The COP drops in very cold weather, but most modern mini splits maintain useful heating down to 5 to 10 degrees Fahrenheit outside. The U.S. Department of Energy covers heat pump efficiency in detail.
How this compares to central AC
A 3 ton central air conditioner draws 3,000 to 3,500 watts for the whole house. A single 12,000 BTU mini split draws about one-third as much, because it is only conditioning one zone.
If you are cooling just one or two rooms and would otherwise run the whole central system, the mini split almost always costs less per hour. The situation reverses if you need to cool most of the house, where the central system handles more square footage for a similar watt draw. That trade-off is covered in more detail in the central air conditioning running cost guide.
For sizing, if you are not sure which head matches your room, the what size mini split do I need for a room guide walks through the square footage math and explains why going one size too big can cost more and leave the room clammy.
What actually moves your monthly bill
Three things drive the total:
- Hours of runtime. An inverter mini split left running at a mild setpoint cycles slowly and uses less power per hour. One fighting a very hot room with the setpoint cranked runs closer to rated wattage for longer. The monthly cost you calculate from the table above assumes 8 hours of active cooling; a room that cools fast and then coasts might be closer to 5 or 6 true running hours.
- Your electricity rate. At 25 cents per kWh (typical in several northeastern and western states), all the numbers in the table above are about 47 percent higher.
- Leaks and sun. A drafty room or one with afternoon west-facing windows pushes the unit harder for longer. Air sealing and shading the glass cuts runtime more than any setting change.
Find your own number
To price your exact setup, you need two things: the wattage from the unit’s nameplate or spec sheet, and your electricity rate from a recent bill. Plug those into the energy cost calculator and it returns the cost per hour, per day, and per month with the math shown. Adjust the hours to match how you actually use the room and you get a realistic seasonal estimate rather than a worst-case number.