It costs $0.16 per hour to run a standard-size 12,000 BTU (one ton) mini-split air conditioner. So, logically, a 24,000 BTU (2-tone) mini-split would cost $0.32/hour to run, and a three-ton (36,000 BTU) unit would cost $0.48/hour to run.
However, these are standard costs for optimal conditions. For example, it may cost slightly more to run the same 12,000 BTU mini-split in a poorly insulated home because the unit needs to work harder. Meanwhile, it costs significantly less to run the AC in typically cool climates.
The rest of this guide attempts to determine the actual costs based on the AC and your geographical location.
Let’s begin with the standard formula for calculating the cost of running any air conditioner. The easiest way to calculate the cost of running an AC is as follows;
Cost/hour = kW (capacity of the AC) x electricity price/hour (based on your power provider tariffs)
What’s my AC wattage in kW?
It’s the rate at which the AC consumes electricity. The power rating is almost always indicated on the Energy Guide (yellow sticker) on the appliance. It’s mandatory under the law for all HVAC appliances to have the energy guide label. If you can’t find it, enquire from the manufacturer.
Alternatively, assuming a perfectly efficient AC (100% efficient), you can determine the likely power rating of the AC by converting the BTUs/hour value to kilowatts/hour. One (1.0) BTU = 0.000293 kilowatts/hour. Therefore, a one-ton (12,000) BTU AC consumes roughly 12,000 x 0.000293 = 3.516 kilowatts/hour.
A two-ton unit would consume twice the amount, i.e., about 7.034 kilowatts/hour, while a 3-ton unit would consume about 10.55 kilowatts/hour.
What’s my electricity price/hour?
The price of electricity varies from one country to another and from state to state. Currently, the national average is 13.19 cents per kilowatt-hour. However, the figure is slightly higher for residential consumers at 13.31 cents.
Based on states, Hawaii leads the lot by being the most expensive state for electricity, with consumers paying 34.43 cents per kilowatt/hour. Washington is the cheapest state at just 9.35 cents per kilowatt-hour.
It’s okay to use the national average for the calculations. However, as you can see, it’ even better to use your state’s rates as the difference from one to the next can be huge. In addition, it would be best to ask your electricity provider for their most up-to-date rates.
Finding your AC running cost/hour
Once you know the power consumption rate of your AC and your provider’s electricity rates, multiply the two to determine how much you’ll likely pay per hour to run the AC.
For instance, if you’re using a one-ton (12,000 BTU) AC rated at 3.516 kilowatts/hour, and you live in Hawaii, where the current average price for electricity is $0.3443 (34.43 cents), you’d pay in the region of $1.21/hour to run the AC. For a 3-ton (36,000 BTU) air conditioner, it’d cost you about $3.63/hour.
Meanwhile, if you live in Washington, a 12,000 BTU AC would cost 3.516 x $0.0935 = $0.33/hour, while a 3-ton unit would cost about $0.986 per hour to run.
Remember that these are running costs at maximum speed. Very rarely do consumers run the AC at full speed, which explains the slightly lower figures initially. Most ACs run at half capacity for the better part of the summer.
Cost to Run AC Per Year
An even more important metric for most consumers is how much you can expect to spend on running the AC over an entire year.
To determine the cost to run a mini-split per year, you need first to determine;
- The average cost of cooling per day
- The number of cooling days in a year
The first one is easy. Assuming that you’re using a one-ton (12,000) BTU air conditioner and paying at the national average of 13.19 cents/kilowatt-hour, you’d pay $0.46/hour and around $3.71/day (assuming you use the appliance for 8.0 hours/day).
The number of cooling days in a year – days with temperatures higher than 65˚F – also known as cooling degree days (CDDs) vary from one country to another and one state to the next.
For instance, the southern states of Texas, Arizona, and Oklahoma have more cooling days than the mid-western states of Minnesota and North Dakota. You’ll need specific data for your country or state for accurate calculations.
However, the average figure for the US is 135 days per year or about three and a half months of cooling. So if we use this figure, you’d part with up to $3.71*135 = $501/year.
It’s important to keep in mind that these are generalized figures. Most consumers pay way less because they rarely run their ACs at 100% capacity.
Factors that May Impact the Total Cost
As you can already tell, the four main factors that determine the cost of running a mini-split AC are the power rating of the unit (in kilowatt-hours), the cost of electricity in your area, and how much you use the appliance (hours per day and days per heating season).
However, a few other factors may come in too, including;
- Efficiency: High-efficiency air conditioners put most of the electricity drawn from your power lines to good use. The result is that they draw less electricity to perform the same task compared to lower-efficiency models. Consider an EER value of 10+ and a SEER value of 16+.
- Quality of maintenance: A well-maintained air conditioner typically consumes less electricity compared to a poorly maintained one. Why? Because blocked filters and a faulty fan cause the AC to work harder. Working harder means the unit draws more electricity to achieve even basic operating levels.
- Room insulation: If your home/room is poorly insulated, be prepared for higher electricity bills. Most of the cool air will be lost via gaps along with window frames and below the door. Arm air may also enter the room through the walls. In the end, your AC must run harder than necessary to keep you cool.
The Final Bill Depends on Multiple Factors
Even the location of the room inside the house and its purpose (is it an entertainment room, home office, bedroom, etc.?) will determine how much you pay to run the mini split air conditioner.
To keep the bill low, be prudent. Keep the thermostat at 22-26 degrees Celsius, turn off all appliances not currently in use, and keep the doors and windows closed.