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Mini-Split Running Cost Per Month: Real Numbers by Size (2026)

by Dua Jones April 14, 2026

The monthly running cost of a mini-split depends on three things: the unit's BTU size, how many hours per day it runs, and your local electricity rate. A 12,000 BTU mini-split running 8 hours a day costs roughly $27–$38 per month for cooling in most US markets. This guide breaks down real numbers for every common size.

Monthly Running Cost by Size (Cooling Mode)

Unit Size	Avg. Wattage	Monthly kWh (8 hrs/day)	Monthly Cost (US @ $0.16)	Monthly Cost (CAD @ $0.13)
6,000 BTU	350–500W	85–120 kWh	$14–$19	$11–$16
9,000 BTU	500–750W	120–180 kWh	$19–$29	$16–$23
12,000 BTU	700–1,000W	170–240 kWh	$27–$38	$22–$31
18,000 BTU	1,000–1,500W	240–360 kWh	$38–$58	$31–$47
24,000 BTU	1,400–2,000W	340–480 kWh	$54–$77	$44–$62
36,000 BTU	2,000–3,000W	480–720 kWh	$77–$115	$62–$94

Monthly Running Cost in Heating Mode

Unit Size	Moderate Climate (US)	Cold Climate (US)
9,000 BTU	$25–$40	$35–$55
12,000 BTU	$35–$55	$50–$75
18,000 BTU	$50–$75	$70–$110
24,000 BTU	$65–$100	$90–$145

Mini-Split vs Other Systems: Monthly Cost

System	Monthly Cooling (500 sq ft)	Monthly Heating (500 sq ft)
Mini-split (12,000 BTU)	$27–$38	$35–$75
Window AC (12,000 BTU)	$45–$70	N/A — cooling only
Portable AC (12,000 BTU)	$55–$85	N/A — cooling only
Electric baseboard (one room)	N/A	$80–$180
Space heater (1,500W)	N/A	$55–$85

How to Calculate Your Specific Monthly Cost

(Average wattage ÷ 1,000) × hours per day × 30 days × your electricity rate = monthly cost.

Example: A 12,000 BTU unit at 800W average, running 8 hours/day at $0.16/kWh:
(800 ÷ 1,000) × 8 × 30 × $0.16 = $30.72 per month.

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Tips to Lower Your Monthly Cost

Clean the filter every 2–4 weeks. A dirty filter increases energy use by 5–15%.
Set a consistent temperature. Inverter systems are most efficient maintaining a steady setpoint.
Use sleep mode at night. Reduces fan speed and adjusts temperature gradually.
Close doors and windows. Open doors let conditioned air escape.
Use a timer or schedule. Avoid running the unit in empty rooms.

Frequently Asked Questions

Does a mini-split use a lot of electricity?

No. A 12,000 BTU mini-split uses about as much electricity as a hair dryer on medium — but it runs at much lower power most of the time thanks to the inverter compressor. Monthly costs are typically $25–$65.

Is it cheaper to run a mini-split or a space heater?

A mini-split is significantly cheaper for heating. A 1,500W space heater produces 5,100 BTU at a COP of 1.0. A mini-split producing the same 5,100 BTU uses only 500–700W because of its heat pump efficiency (COP 2.5–4.0). Roughly half the cost per hour.

How much does it cost to run a mini-split 24/7?

Running a 12,000 BTU unit continuously would cost approximately $80–$120 per month at $0.16/kWh. In practice, the inverter compressor ramps down to very low power at the setpoint, so 24/7 operation does not mean 24/7 full-power consumption.