Mini-split air conditioners ranked by cost to run
Ductless mini-split systems and heat pumps — the most efficient option for a fixed install. Ranked by real running cost per hour.
- Typical efficiency
- SEER 18–22
- Power (12k BTU)
- ~850–1,000 W
- Cost/hr (UK)
- ~£0.20–0.22
- Install
- Pro · £400–1,000
- Noise
- 19–30 dB
Typical figures for a 12,000 BTU unit at UK rates (£0.245/kWh) — see the live listings below for exact specs per model.
Guides for mini-split air conditioners
Mini-split air conditioners: frequently asked questions
How much does a mini-split cost to run?
Ductless mini-splits are the most efficient AC type, averaging an EER around 12 (SEER often 18–22+). A 12,000 BTU mini-split draws under about 1,000 W at full load and much less when modulating — typically the lowest cost per hour of any type for a given BTU.
Are mini-splits cheaper to run than window or portable units?
Yes. Their high SEER/EER and inverter compressors give the lowest running cost per hour in our rankings. Over a season the efficiency gap versus a portable can outweigh the higher purchase and install cost.
What is the difference between a mini-split and a regular split?
Both have an indoor and outdoor unit. "Mini-split" usually denotes a compact ductless system (often heat-pump capable, sometimes multi-zone); in practice the terms overlap, and we rank both by what they cost to run per hour.
Do mini-splits work as heat pumps?
Most do. Reverse-cycle mini-splits heat at a COP around 3–4, making them one of the cheapest ways to heat a room electrically. Use the heat-pump-only filter in the table to see them.
