Room size calculator
Size the unit before you spend a penny
Undersized units never cool; oversized ones cycle badly and cost more. Sixty seconds here prevents the single most common (and expensive) air-conditioning mistake.
Enter your room's length and width
to see the estimate.
How the estimate works
We start from the standard sizing baseline for UK rooms (roughly 337 BTU per square metre at 2.4 m ceilings) and adjust for ceiling height, sun exposure, occupancy, heat-emitting equipment, room type and insulation. The result is snapped to common unit sizes so it maps to what you can actually buy.
What it deliberately isn't: a professional heat-load survey. Real surveys measure glazing, orientation, construction and ventilation — which is why every Coolhaven installation includes one before a final quote, and why portable recommendations are always confirmed against your details before purchase.