AC size calculator: what ton AC does your room need?
Six quick questions. We work out the heat load line by line the way Daikin's engineers do, for the hottest afternoon of a normal year in your city, then show only the ACs that still have the power at that heat.
Answer six questions: the room type, its length and width, the floor, when sun falls on the main window, how many people use it, and your city (Delhi NCR and 54 weather stations across India). The calculator works out the heat load line by line with Daikin's heat-load method for your city's hottest afternoon and its monsoon, checks which ACs still have the power at that heat, and shows the Daikin ACs that fit with today's price and stock. Detailed mode adds ceiling height, room temperature, glass type and area, roof insulation, lighting, equipment, safety margin and your electricity rate, with the full line-by-line breakdown.
AC size by room size
Bedroom with two people in Delhi, room held at 24°C, on a 45.3°C afternoon, the hottest day of an average year. Each size is the smallest that still covers the room at that heat, after the AC loses power to it. Living rooms, offices and kitchens need more: use the calculator for those.
The simple answer: what size AC do I need for my room?
| Room | Shaded, middle floor | Afternoon sun, middle floor | Afternoon sun, top floor |
|---|---|---|---|
| 10 × 10 ft 100 sq ft | 1.0 Ton 0.81 TR | 1.0 Ton 0.94 TR Models rated to 46°C | 1.5 Ton 1.10 TR |
| 10 × 12 ft 120 sq ft | 1.0 Ton 0.89 TR Models rated to 46°C | 1.5 Ton 1.05 TR | 1.5 Ton 1.24 TR |
| 12 × 12 ft 144 sq ft | 1.0 Ton 0.96 TR Models rated to 46°C | 1.5 Ton 1.13 TR | 1.5 Ton 1.35 TR Models rated to 46°C |
| 12 × 14 ft 168 sq ft | 1.5 Ton 1.06 TR | 1.5 Ton 1.24 TR | 1.8 Ton 1.51 TR |
| 12 × 15 ft 180 sq ft | 1.5 Ton 1.10 TR | 1.5 Ton 1.30 TR Models rated to 46°C | 1.8 Ton 1.59 TR Models rated to 46°C |
| 14 × 14 ft 196 sq ft | 1.5 Ton 1.13 TR | 1.5 Ton 1.32 TR Models rated to 46°C | 1.8 Ton 1.63 TR Models rated to 46°C |
| 15 × 15 ft 225 sq ft | 1.5 Ton 1.23 TR | 1.5 Ton 1.43 TR JTKJ only | 2.5 Ton 1.78 TR |
| 16 × 16 ft 256 sq ft | 1.5 Ton 1.32 TR Models rated to 46°C | 1.8 Ton 1.54 TR Models rated to 46°C | 2.5 Ton 1.94 TR |
| 15 × 20 ft 300 sq ft | 1.5 Ton 1.48 TR JTKJ only | 2.0 Ton 1.75 TR | 2.5 Ton 2.22 TR |
The same room across India
12 × 12 ft bedroom (144 sq ft), two people, window with afternoon sun, room held at 24°C. Hottest afternoon: the hottest day of an average year (IMD), or the IS 7896 design temperature plus 3°C where IMD does not publish it.
| City | Hottest afternoon | Middle floor | Top floor |
|---|---|---|---|
| Delhi | 45.3°C IMD | 1.5 Ton 1.13 TR | 1.5 Ton 1.35 TR Models rated to 46°C |
| Jaipur | 45.8°C Estimate | 1.5 Ton 1.13 TR | 1.5 Ton 1.36 TR Models rated to 46°C |
| Lucknow | 45.0°C Estimate | 1.5 Ton 1.12 TR | 1.5 Ton 1.34 TR Models rated to 46°C |
| Ahmedabad | 45.3°C Estimate | 1.5 Ton 1.13 TR | 1.5 Ton 1.35 TR Models rated to 46°C |
| Nagpur | 46.8°C Estimate | 1.5 Ton 1.18 TR Models rated to 46°C | 1.5 Ton 1.41 TR JTKJ only |
| Patna | 43.7°C Estimate | 1.5 Ton 1.07 TR | 1.5 Ton 1.30 TR |
| Bhopal | 44.7°C Estimate | 1.5 Ton 1.08 TR | 1.5 Ton 1.31 TR All but GTKC, GTKL and FTHT |
| Amritsar | 45.6°C IMD | 1.5 Ton 1.12 TR | 1.5 Ton 1.33 TR Models rated to 46°C |
| Hyderabad | 43.4°C Estimate | 1.5 Ton 1.05 TR | 1.5 Ton 1.27 TR |
| Kolkata | 39.8°C IMD | 1.0 Ton 0.97 TR All but GTQ | 1.5 Ton 1.20 TR |
| Chennai | 41.4°C Estimate | 1.5 Ton 1.04 TR | 1.5 Ton 1.27 TR |
| Mumbai | 38.3°C Estimate | 1.0 Ton 0.90 TR | 1.5 Ton 1.12 TR |
| Pune | 41.4°C Estimate | 1.0 Ton 0.95 TR | 1.5 Ton 1.15 TR |
| Bengaluru | 37.2°C IMD | 1.0 Ton 0.80 TR | 1.0 Ton 0.99 TR All but GTQ |
| Guwahati | 37.4°C Estimate | 1.0 Ton 0.91 TR | 1.5 Ton 1.13 TR |
How the calculator works
Line by line, the Daikin way
We follow Daikin's own heat-load sheet: sun through the glass, heat through the walls, roof and floor, people, lights, gadgets and fresh air, each with the same factors and the same safety margins.
Your city's hottest afternoon
An AC has to hold the room on the hottest day of a normal year, not an average one. For 54 Indian weather stations we use the Bureau of Indian Standards design data (IS 7896) and IMD climate records. In Delhi that day reaches 45.3°C.
The monsoon too
Humid monsoon days are cooler but carry far more moisture for the AC to take out. We work out both and size for the bigger.
Rooms around yours
We take the average case: half the inside walls, floor and ceiling face rooms that are not air-conditioned, which is how most homes are used.
The AC's own limit
Every AC loses power when it is very hot outside. Daikin models keep full power up to 43°C or 46°C, depending on the series; above that we take off 5% for every degree. We only show ACs that still cover the room at your hottest afternoon.
Then the right size
The answer is the smallest size we sell that still keeps up. 1 TR is 12,000 BTU/hr of cooling.
Frequently asked questions
What size AC do I need for a 12×12 room?
A 12×12 room is 144 sq ft. In Delhi, as a bedroom on a middle floor, it needs 0.96 TR with a shaded window, so a 1.0 Ton AC rated to 46°C, or a 1.5 Ton, and 1.13 TR with afternoon sun, so a 1.5 Ton AC. On a top floor with afternoon sun it needs 1.35 TR: a 1.5 Ton AC rated to 46°C, or a 1.8 Ton.
Will a 1 ton AC cool a 144 sq ft room on the top floor?
No. On a 45.3°C Delhi afternoon that room needs 1.19 TR with a shaded window and 1.35 TR with afternoon sun. The most a 1 ton AC gives is 1.00 TR, and a model rated to 43°C drops to 0.89 TR at that heat. The roof slab is the difference: it bakes all day and keeps giving off heat into the night. Get a 1.5 Ton AC rated to 46°C, or a 1.8 Ton.
Is a 1.5 ton AC enough for 200 sq ft?
Yes on a middle floor, but not on a top floor with afternoon sun. In Delhi a 200 sq ft bedroom on a middle floor needs 1.15 TR with a shaded window (a 1.5 Ton AC) and 1.34 TR with afternoon sun (a 1.5 Ton AC rated to 46°C, or a 1.8 Ton). On a top floor with afternoon sun it rises to 1.65 TR, which needs a 1.8 Ton AC rated to 46°C, or a 2.0 Ton. A living room of the same size needs more, because more people use it.
Why does an AC lose cooling in a heatwave?
An AC pushes the heat it takes out of the room into the outside air. The hotter that air, the harder it gets. Daikin models give full power up to 43°C or 46°C, depending on the series, and lose about 5% for every degree above. On a 45.3°C Delhi afternoon a 5.0 kW (1.5 ton) AC rated to 43°C gives 1.26 TR, while one rated to 46°C still gives its full 1.42 TR. At 48°C they give 1.07 TR and 1.28 TR.
How much bigger does the AC need to be on a top floor?
For a 12×14 bedroom with afternoon sun in Delhi, about 21% bigger: 1.24 TR on a middle floor, 1.51 TR on the top floor. That is a 1.5 Ton AC against a 1.8 Ton AC.
Does the city change the AC size?
Yes. The same 12×12 bedroom with afternoon sun on a middle floor needs 1.13 TR in Delhi (a 1.5 Ton AC), 0.90 TR in Mumbai (a 1.0 Ton AC) and 0.80 TR in Bengaluru (a 1.0 Ton AC). Pick your city in the calculator: it covers 54 weather stations across India.
Is a 5 star AC worth the extra cost?
It depends on how many hours you run it. For a 12×12 Delhi bedroom with afternoon sun, at ₹8 a unit, a 5 Star saves about ₹1,696 a year over a 3 Star at 8 hours a day, and about ₹3,392 a year at 16 hours. The calculator divides the price gap of the actual models in stock by that saving, and tells you how many years the 5 Star takes to pay for itself.
When does a room need two ACs?
When no single split AC we sell covers it on the hottest afternoon: the biggest is 2.5 Ton, and one unit cannot spread more cooling than that evenly. A 20×20 living room on a top floor with afternoon sun in Delhi, for example, needs 3.09 TR. Above 3.5 TR in one room, a cassette, ductable or VRV system is the better fit, and our engineers design those.
What does TR (ton) mean on an AC?
One ton of refrigeration (1 TR) is 12,000 BTU per hour, or 3.517 kW of cooling. It has nothing to do with weight. The "1.5 ton" on the box is a class: Daikin's 1.5 ton models deliver 5.0 to 5.28 kW, which is 1.42 to 1.50 TR. The calculator uses the real figure, not the label.
Why does the calculator round up instead of down?
An AC can only remove as much heat as its capacity. If a room needs 1.2 TR and gets an AC that gives 1.0, it never reaches 24°C on the hottest afternoons. An inverter AC slows down once the room is cool, so a little spare capacity costs very little to run.
Not sure? Call +91 77039 00307 or WhatsApp our team. Sales and service under one roof, cooling Delhi since 1990. Browse all Daikin ACs.