What Size Air Conditioner Do I Need for My UK Home?

Choosing the right size air conditioning system is key to getting the best performance, energy efficiency, and comfort. But “size” doesn’t just mean physical dimensions – it’s about the cooling (and heating) capacity.

Here’s a quick guide to help you understand what size AC unit you might need for your space.

Why Size Matters

An AC system that’s too small will struggle to cool your room, while an oversized unit may cycle on and off too frequently, wasting energy and wearing out faster.

Things to Consider:

• Room Size: Larger rooms need more cooling power. As a rough guide, a small bedroom may only need 2–2.5kW, while an open-plan lounge might require 5kW or more.

• Sunlight: South-facing rooms or those with big windows may need a slightly more powerful unit.

• Insulation & Property Type: Well-insulated homes need less cooling than older or poorly insulated ones.

• Ceiling Height: Higher ceilings mean more air to cool, so this affects the calculation too.

Need Help Choosing?

We offer free advice and quotes to help you choose the perfect AC unit for your space. We’ll assess your room size, layout, insulation, and usage so you get a solution that works — first time.