Mini Split Cost to Run (Monthly Calculator)
What a mini-split costs to run per month — a live calculator (BTU ÷ SEER2 × hours × your electricity rate) plus a cost-by-size table and the factors that change your bill.
Prices vary by location. Verify with local suppliers.
What a mini-split costs to run
Most mini-splits cost $20–$60 a month to run (full range $15–$100), at the US average electricity rate of about 18¢/kWh. The calculator above prices your exact size, efficiency, runtime and rate. The math is simple and worth seeing:
Monthly cost = (watts ÷ 1,000) × hours/day × 30 × your $/kWh · watts ≈ BTU ÷ SEER2
Typical running cost by size (20 SEER2, 8 hrs/day, 18¢/kWh)
| Size | Avg power | Cost / month |
|---|---|---|
| 9,000 BTU | ≈ 450 W | ≈ $20 |
| 12,000 BTU | ≈ 600 W | ≈ $26 |
| 18,000 BTU | ≈ 900 W | ≈ $39 |
| 24,000 BTU | ≈ 1,200 W | ≈ $52 |
| 36,000 BTU | ≈ 1,800 W | ≈ $78 |
Heating draws about 20–40% more per hour than cooling. A higher SEER2 unit runs 20–25% cheaper than a low-efficiency one, and mini-splits run 30–40% cheaper than central AC thanks to no duct losses and inverter modulation. Dirty filters can add 5–30% — keep them clean.
Frequently asked questions
How much does a mini split cost to run per month?
Most mini-splits run about $15–$100 per month, with typical homes at $20–$60 at the roughly 18¢/kWh US average rate. A 12,000 BTU unit at 20 SEER2 running 8 hours a day costs about $26 per month. The calculator above prices it for your exact size, runtime and rate.
How much electricity does a mini split use?
Roughly 600–2,000 watts depending on size and efficiency — wattage is about BTU ÷ SEER2. A 12,000 BTU / 20 SEER2 unit averages near 600 watts and about 4.8 kWh over an 8-hour day, though the inverter compressor idles down when the room is at temperature, so real use is often lower.
Does SEER2 really lower running cost?
Yes — a 22 SEER2 unit runs about 20–25% cheaper than a 16 SEER2 unit at the same BTU and runtime, and each point above SEER2 16 saves roughly 5–8%. Over years of cooling and heating, a higher-efficiency unit’s lower bills offset much of its higher purchase price.
Are mini splits cheaper to run than central air?
Typically yes — about 30–40% cheaper, because they have no duct losses and their inverter compressors modulate output instead of cycling fully on and off. Zoning helps too: you only condition the rooms you’re using, rather than the whole house.