AC Tonnage Calculator – Find the Right AC Size for Your Room

Choosing the wrong AC tonnage is one of the costliest appliance mistakes Indian homeowners make. An undersized AC runs non-stop without ever fully cooling the room. An oversized one short-cycles — cools quickly but can’t dehumidify, leaving the air clammy. Our AC Tonnage Calculator gives you a precise recommendation based on your actual room, floor, orientation, and city climate — not the generic “1 ton per 100 sq ft” thumb rule that consistently fails Indian homes.

How to Use the AC Tonnage Calculator

1. Enter your room area in square feet or square metres.
2. Select your floor type — top-floor rooms in India absorb far more radiant roof heat than middle or ground floor rooms.
3. Choose room orientation — west-facing rooms get harsh afternoon sun and need extra capacity.
4. Select your city or climate zone — Delhi, Mumbai, Hyderabad, and Chennai have different heat loads.
5. Enter occupants and heat-generating appliances — each person adds roughly 100 W of heat load.
6. Click Calculate to get your recommended AC tonnage.

AC Tonnage Quick Reference Chart (India)

Room Size	Middle / Ground Floor	Top Floor or West-Facing
Up to 120 sq ft	0.75 – 1 Ton	1 – 1.2 Ton
120–180 sq ft	1 Ton	1.2 – 1.5 Ton
180–240 sq ft	1.5 Ton	1.5 – 1.8 Ton
240–320 sq ft	1.5 – 2 Ton	2 Ton
320–400 sq ft	2 Ton	2 – 2.5 Ton
400+ sq ft	2.5 Ton or dual units	2.5+ Ton

Why the Standard Thumb Rule Fails Indian Homes

The “1 ton per 100 sq ft” formula was designed for temperate climates. In Indian cities where summers cross 42–45°C and top-floor flats bake under concrete roofs all day, this rule undersizes your AC by 20–40%. Our calculator accounts for real Indian heat load factors so you don’t overbuy or underbuy.

Deep dive: Why the AC thumb rule fails for top-floor flats and west-facing rooms →

Frequently Asked Questions

What does AC tonnage actually mean?

AC tonnage is a measure of cooling capacity, not weight. 1 ton equals 3,517 watts of heat removal per hour. A 1.5 ton AC removes 5,275 watts of heat from your room every hour. Higher tonnage means it can handle a larger room or a room with a higher heat load (hotter city, top floor, large windows).

Is 1 ton AC enough for a 12×12 ft room?

For a 12×12 ft room (144 sq ft) on a middle or ground floor in a moderate climate, 1 ton is sufficient. But if your room is on the top floor, faces west, or is in a hot city like Delhi or Chennai, upgrade to 1.2–1.5 ton for comfortable cooling without the AC straining all day.

1.5 ton or 2 ton for a 200 sq ft room?

For a standard 200 sq ft room on a middle floor, 1.5 ton is right. If your room is on the top floor, faces west, has tall ceilings, or is in Rajasthan/Gujarat/Telangana where heat is intense, go with 2 ton — it’ll actually be more efficient because it won’t run at full load continuously.

Can a 5-star AC compensate for being undersized?

No. Star rating (ISEER) measures energy efficiency — how much electricity the AC uses per unit of cooling. It doesn’t increase the AC’s cooling output. An undersized 5-star AC will still run at 100% load all day and may not cool the room adequately. Always size correctly first, then choose the highest star rating in your budget.

Does an oversized AC cause problems?

Yes. An oversized AC reaches the thermostat temperature too quickly before it can dehumidify the air — leaving the room feeling cool but humid and clammy. It also short-cycles (turns on and off frequently), which stresses the compressor and increases electricity bills. Correct tonnage = better comfort + lower running cost.

What tonnage for a hall or drawing room?

Most Indian living rooms are 250–400 sq ft. A 2 ton AC is the standard recommendation. For open-plan spaces above 400 sq ft or combined living-dining areas, consider a 2.5 ton unit or two 1.5 ton units for even air distribution.

Also read: Should you wait for Diwali sale to buy an AC in India? → | Explore all free calculators →