Are mini splits expensive to run? Cost per hour and month

30-second answer

$0.23 an hourverified Sep 2026

Usually not, compared with other electric heat. At the U.S. average residential rate of 18.31 cents per kWh, a mini split covering the design-day heat for a 400 sq ft room in climate zone 4 costs about $0.23 an hour. Electric resistance heat costs about $0.51 for the same heat.^[1][2][3]

• The formula is short. Cost per hour is the heat you need, divided by 3,412 BTU per kWh and by the unit’s COP, times your rate.^[2]
• Your rate moves the bill more than the model. July 2026 state averages run from 12.72 cents in Louisiana to 48.00 cents in Hawaii.^[1]
• Cold raises the cost of each unit of heat. One NEEP-listed model needs 91 percent more electricity per unit of heat at 5°F than at 47°F.^[3]

Swap in your own rate from your bill.

How much does it cost to run a mini split per hour and per month?

For one example room, about $0.23 an hour at the design-day load. The room is 400 sq ft, with average insulation and an 8-foot ceiling, in climate zone 4. Our sizing calculator screens its heat load at 9,500 BTU/h at 5°F, a typical zone 4 design temperature. That temperature is our screening value, not a published one.

Here is the math at 18.31 cents per kWh^[1]:

• Heat needed. 2.78 kW of heat, which is the load divided by 3,412 BTU per kWh.^[2]
• Electricity at a COP of 2.2. 1.27 kW, the COP NEEP lists for the Mitsubishi FX12 at 5°F.^[3]
• Cost. $0.23 an hour, or $23 for every 100 hours at that load.
• Resistance heat, same heat. $0.51 an hour, because a COP of 1 uses 2.78 kW.

In our judgement, treat these as ceilings. The design-day load happens on the coldest hours, so most hours run lighter.

How do you calculate a mini split’s running cost?

Multiply the electricity the unit draws by your rate. The draw is the heat you need divided by 3,412 BTU per kWh, then divided by the unit’s COP, its heat delivered per unit of electricity used.^[2]

1. Screen your load. Use the sizing calculator, then confirm it with a load calculation (Manual J).
2. Convert to kW of heat. Divide the load by 3,412.
3. Divide by COP. NEEP lists a COP for each model at its rating points.^[3]
4. Multiply by your rate. Use dollars per kWh from your own bill. The U.S. residential average was 18.31 cents in July 2026, a preliminary figure.^[1] If your plan has tiers or time-of-use hours, use the rate that applies when the unit runs.
5. Multiply by your hours. Add up the hours the unit runs at that load.

How many hours will it run, and what will that cost?

Nobody can print your hours for you, because they depend on your winters and your house. Your own bills are the best check, and the example gives a ceiling to test them against.

• Compare two bills. In our judgement, subtract a mild month’s kWh from a cold month’s kWh. If nothing else changed, the difference is roughly the extra heating.
• Price the difference. Multiply those extra kWh by the rate on the same bill.
• Test it against the ceiling. In the example, 300 hours at the design-day load would cost $70. Real bills should land below that ceiling, because most hours run lighter.

A number far above your ceiling points to a larger room, poorer insulation or a higher rate than the example, so rerun the math with your own inputs. A number far below it usually means the unit runs at partial load most of the time, which is normal for an inverter unit.

What makes a mini split cost more or less to run?

Your rate, your insulation, the outdoor temperature and your run hours do the most work. Each is a number you can change or look up:

• Your rate. At the same example load and COP, Louisiana’s 12.72 cents costs $0.16 an hour and Hawaii’s 48.00 cents costs $0.61.^[1]
• Your insulation. The same room screens at 12,500 BTU/h with poor insulation and 8,000 with good. That is $0.30 and $0.20 an hour at 18.31 cents.
• The outdoor temperature. The FX12’s COP is 4.2 at 47°F and 2.2 at 5°F, so a cold hour needs 91 percent more electricity per unit of heat.^[3]
• Your run hours. Cost is linear: twice the hours at a given load costs twice as much.

Put together, the bill comes mostly from your rate, your load and your hours. The model matters through its COP at your temperatures, and our cold climate mini split heat pump guide compares NEEP capacity at 5°F by model.

Are mini splits cheaper to run than other electric heat?

Yes, per unit of heat. Electric resistance turns one kWh into 3,412 BTU, a COP of 1.^[2] The example model’s COP is 2.2 at 5°F and 4.2 at 47°F, so it needs less than half the electricity at 5°F and less than a quarter at 47°F for the same heat.^[3]

Running cost is only half of the purchase question. Our are mini splits worth it guide prices the upfront side.

The load number is a screening estimate. The heating BTU calculator post explains why a load and a unit size are two different questions.