12,000–18,000 BTU air conditioners ranked by cost to run
Mid-to-large capacity for open-plan living rooms, large bedrooms and small offices — roughly 28–42 m² (300–450 sq ft). Bigger BTU means a bigger power draw, so running cost matters even more. Ranked by cost per hour to run.
- Suits room
- ~28–42 m²
- Power draw
- ~1,000–2,100 W
- Cost/hr (UK)
- ~£0.25–£0.52
- Cheapest type
- Mini-split
Typical ranges for 12,000–18,000 BTU at UK rates (£0.245/kWh) — see the live listings below for exact specs per model.
Guides for 12,000–18,000 btu air conditioners
12,000–18,000 BTU air conditioners: frequently asked questions
What room size does 12,000–18,000 BTU cool?
Roughly 28–42 m² (about 300–450 sq ft) — open-plan living areas, large bedrooms and small offices. Add capacity for south-facing rooms, lots of glazing, high ceilings or kitchens.
Are bigger BTU air conditioners more expensive to run?
Yes — more cooling means more watts. A 15,000 BTU unit draws roughly 25% more power than a 12,000 BTU one of the same efficiency. That’s why efficiency (EER/SEER) and an inverter compressor matter most at this size; an efficient mini-split can cost far less per hour than a cheap portable of the same BTU.
Which type is cheapest to run at 12,000–18,000 BTU?
A ductless mini-split — its high SEER and inverter compressor give the lowest cost per hour. Portables in this range are the most expensive to run. Sort the table by cost per hour to compare.
