Air Conditioning Size Calculator UK

How the Calculator Works

The estimate starts from the room volume (floor area × ceiling height) and applies a cooling factor based on insulation. It then adjusts for solar gain through glazing, adds heat from occupants and equipment, allows for air movement through doors and draughts, and applies a design allowance. The result is matched against the UK total cooling capacity figures from the Midea Solstice sales sheet — the wall-mounted range we quote for straightforward domestic installations.

It also gives early electrical guidance: the smaller Solstice sizes list a maximum current of 10 A, which sometimes allows connection via an existing 13 A fused spur, while larger sizes need a dedicated supply. The air conditioning Leicester page explains why the electrical supply is part of the installation, not an extra.

kW or BTU?

UK specifications quote cooling capacity in kilowatts; BTU/h figures persist from older marketing and imported units. The conversion is simple: 1 kW ≈ 3,412 BTU/h. The calculator shows both so you can compare against any unit you've seen advertised.

Frequently Asked Questions

What size air conditioner do I need for a bedroom?

A typical UK double bedroom of 12–16 m² with average insulation usually lands in the 2.6–3.5 kW (9,000–12,000 BTU/h) class. South-facing rooms, loft rooms and rooms with large glazing need more. Enter your room details in the calculator for a closer estimate.

How do I convert BTU to kW?

Divide BTU/h by 3,412 to get kW. So 9,000 BTU/h is about 2.6 kW, 12,000 BTU/h is about 3.5 kW, and 18,000 BTU/h is about 5.3 kW. UK specifications normally quote kW; BTU figures persist from older marketing.

Can I run air conditioning from a normal plug socket?

Sometimes, for smaller units. The smaller Midea Solstice sizes list a maximum current of 10 A, so a 13 A fused connection may be possible if the manufacturer instructions allow it and the existing circuit is suitable. Many installations still need a dedicated supply with correct protection, an outdoor isolator and certification — this is checked before quoting.

Is a bigger air conditioner always better?

No. An oversized unit cools the air quickly but short-cycles: it switches on and off repeatedly, dehumidifies poorly and wears harder. The right size runs longer at lower output, which is quieter, more comfortable and more efficient.

Is the calculator result a final design?

No. It is a guide based on typical UK domestic conditions. Loft rooms, conservatories, open-plan areas, large glazing and high equipment heat loads need a proper assessment. The final unit size and electrical supply are confirmed after a survey or photo assessment.

Air Conditioning Installation in Leicester

Leicester-Spark Ltd installs domestic wall-mounted split AC in Leicester and nearby areas — F-Gas certified, with the electrical supply assessed, tested and certified by a NICEIC Approved Contractor. Send room photos for an initial assessment and a fixed quote. Installation prices and examples are on the air conditioning Leicester page.