How many watts does a mini-split use?
Reviewed 2026-07-04 · Sources listed below
A 12,000 BTU mini-split uses about 1,000 to 1,200W at full cooling, but because it's inverter driven it averages 300 to 700W once the room reaches temperature. A 9,000 BTU unit peaks near 800W; a 24,000 BTU unit near 2,000W. Heating in cold weather draws more than cooling.
Wattage by mini-split size
| Unit size | Max cooling W | Typical average W | Max heating W | kWh / month* |
|---|---|---|---|---|
| 6,000 BTU | 600 | 200–400 | 800 | ~70 |
| 9,000 BTU | 800 | 250–550 | 1,100 | ~95 |
| 12,000 BTU | 1,100 | 300–700 | 1,500 | ~145 |
| 18,000 BTU | 1,700 | 500–1,100 | 2,200 | ~215 |
| 24,000 BTU | 2,000 | 650–1,400 | 2,800 | ~270 |
| 36,000 BTU | 3,200 | 1,000–2,200 | 4,200 | ~430 |
*Cooling 8 hours/day at the midpoint average draw. Your climate and setpoint move this a lot; use the calculator below with your numbers.
Running cost calculator
Use the "typical average" column above, or your energy monitor's reading.
US average is around $0.17. Your bill shows your exact rate.
Inverter units modulate, so measured averages beat nameplate math. A $20 plug-in energy monitor gives you the real number for 110V units.
Why the average beats the nameplate
A traditional AC is on or off. A mini-split's inverter compressor speeds up and slows down, so after the initial pulldown it might idle along at 300W holding your setpoint. That's the whole efficiency story, and it's why sizing matters: an oversized unit never settles into that low cruise. If you're still choosing a size, start with the BTU calculator.
Frequently asked
How much electricity does a mini-split use per month?
A 12,000 BTU unit cooling 8 hours a day at an average 600W draw uses about 144 kWh a month, which is roughly $24 at the US average rate near 17 cents per kWh. Heavy summer use in a hot climate can double that.
Why does my mini-split use less power than its rating?
Because it is inverter driven. It runs at full draw only while pulling the room down to temperature, then modulates down to a fraction of rated power to hold it. This is why measured averages sit well below nameplate watts.
Does heating use more watts than cooling?
Often yes, especially in cold weather. Heat pump efficiency drops as outdoor temperature falls, so the same unit that averages 600W cooling may average 900 to 1,500W heating on a freezing day, plus defrost cycles.
Can I run a mini-split on a 15 amp circuit?
Small 110V units (6k to 12k BTU) often can; check the spec sheet for MCA (minimum circuit ampacity) and MOP (maximum overcurrent protection). Larger units are 220V and need their own circuit. An electrician confirms this in minutes.
Do mini-splits use a lot of power on standby?
A few watts to around 30W to keep the crankcase heater and electronics alive. It is small but real: about 1 to 3 dollars a month if you leave it powered year round.
Related tools
Sources
- Manufacturer spec sheets (rated input, cooling and heating): Mitsubishi, Daikin, MRCOOL, Senville.
- US EIA average residential electricity rate.
- Inverter modulation behavior per manufacturer engineering data and measured owner data.