What is it?
The AC Size Calculator works out the Cooling needed (BTU/h), In tons, and a Suggested AC for your room.
Who is it for?
Families buying an AC, shop and office owners, and electricians advising customers.
How to use it
- Enter the Room area and choose the Unit (square feet or metres).
- Say how much sun the Room gets: Mostly shade, Normal sun or Lots of sun / top floor.
- Enter People usually in the room. Tick It is a kitchen or Very hot climate (45 °C summers) if they apply.
How it is worked out
It is based on the ENERGY STAR sizing chart with its sun, people and kitchen adjustments. Very hot climates, poor insulation and top floors may need the next size up.
Rough guide
- Up to about 120 sq ft: 1 ton. 120–180 sq ft: 1.5 ton. 180–250 sq ft: 2 ton, for normal conditions.
- Rooms with high ceilings (over 10 ft), large glass windows or a top floor under a concrete roof need more.
Too big or too small?
Too small runs non-stop and never cools well. Too big cools quickly but switches off before removing humidity, leaving the room damp and cold. An inverter AC handles small oversizing better. Prefer a higher star rating for long daily use.
Worked example
A 160 sq ft bedroom with lots of sun on a top floor and 2 people usually needs a 1.5-ton AC.
Errors and how to fix them
- “Enter the room area (more than 0)”: multiply the room’s length by its width, type it in Room area and choose the Unit.
- The suggested tonnage seems high: top-floor rooms, west-facing windows, many people or a kitchen nearby all add heat. Use the size the tool shows, not a smaller one, or the AC will run all day.
Open the tool: AC Size Calculator
Still stuck?
Contact support. Tell us which tool or page you were using, what you tapped, what you saw, and your phone or computer and browser (for example: Android phone, Chrome). We reply by email.
Questions, or an error not listed here?
Tell us in the comments: what you were doing, the exact message you saw, and your device and browser. We read every comment and add new fixes to this article.