AC tonnage for your room
A rough guide to choosing 1 ton, 1.5 ton or 2 ton for a room in a Kolkata home, and the things that push the size up.
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- Warranty: 90 days on the work done
What size AC do I need for my room?
As a rough guide, about 1 ton suits a room up to 120 sq ft, 1.5 ton suits 120 to 180 sq ft, and 2 ton suits 180 to 240 sq ft. Go one size up if the room gets strong sun, sits on the top floor under the roof, or usually has several people or heat-giving appliances in it. These figures are a starting point, so have the room checked before you buy.
What a ton means
A ton is a measure of cooling, not weight. One ton of cooling is 12,000 BTU per hour, or about 3.5 kW of heat removed. A 1.5 ton AC can remove one and a half times as much heat as a 1 ton AC.
Rough sizes by room area
Measure the length and width of the room in feet and multiply them. Then use this as a first guess for a room with a normal ceiling:
- Up to about 120 sq ft, such as a small bedroom or study: around 1 ton
- About 120 to 180 sq ft, such as a main bedroom: around 1.5 ton
- About 180 to 240 sq ft, such as a large bedroom or living room: around 2 ton
- Above 240 sq ft or an open hall: more than 2 ton, or two units
What pushes the size up
- Afternoon sun on a wall or large windows
- A top-floor room under a roof slab that heats up all day
- A high ceiling
- Three or more people in the room most of the time
- A kitchen, a computer, a TV or other heat sources in or next to the room
- A room open to a dining area or passage, which you have to count in the area
Why bigger is not always better
A fixed-speed AC that is too big cools the air fast and switches off before it has pulled much moisture out. The room can feel cold and clammy, which matters in a humid city. It also costs more to buy and draws more power when it runs.
An AC that is too small runs flat out through May and June and still does not reach the set temperature. An inverter AC handles a little extra size better, because it can slow down once the room is cool.
When to call us
We are an authorised dealer for Carrier Midea and Blue Star ACs, and we install split and window ACs of most brands. If you are unsure of the size, ask the technician to look at the room. Price for installation: From ₹1,299 split, ₹799 window. See AC installation.
Questions
Is a 1.5 ton AC enough for a 150 sq ft room?
For a room of about 150 sq ft with a normal ceiling and little direct sun, 1.5 ton is the usual choice. On the top floor or with strong afternoon sun, think about the next size up.
Can one AC cool two rooms?
Not well. Cool air does not travel far through a doorway, so the second room stays warm and the AC runs longer. One AC sized for each room works better.
Does a higher star rating change the size I need?
No. The star rating tells you how much power the AC uses for its cooling. The tonnage tells you how much cooling it gives. Pick the size for the room first, then compare star ratings.
Last updated 2026-11-08
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