Free tool
AC Tonnage Calculator
Find the right air-conditioner size — 0.75, 1, 1.5 or 2 ton — for a room in Raipur, Bhopal or any hot Indian city, with top-floor and sun-facing rooms accounted for.
How to use
How to use the AC tonnage calculator
- Enter the room’s length, width and ceiling height in feet.
- Pick your city. Central Indian summers regularly cross 44 °C, which adds to the load.
- Tick top floor or sun-facing if the roof or a west/south wall bakes in the afternoon.
- Set people and heat sources — a home office or open kitchen needs more cooling than a bedroom.
- Read the recommended tonnage and the notes on inverter models and star ratings.
The maths
How it’s calculated
Base tons = floor area ÷ 140 sq ft
× ceiling height ÷ 10 ft
× climate (Raipur 1.10, Bhopal 1.05, mild cities 0.90)
× 1.15 if top floor × 1.10 if sun-facing
+ 0.05 ton for each person beyond two
+ heat sources (0.1–0.4 ton)
1 ton = 12,000 BTU/h = 3.517 kW of cooling
The result is rounded up to the next standard size, allowing 5% tolerance. This is a rule of thumb for typical brick-and-RCC Indian homes; a proper heat-load calculation also looks at insulation, glazing and air leakage.
Worked example
A 14 × 12 ft bedroom in Raipur
- Area 168 sq ft ÷ 140 = 1.20 ton at a 10 ft ceiling.
- Raipur climate × 1.10 = 1.32 ton → a 1.5 ton AC.
- If it is on the top floor with a west wall: × 1.15 × 1.10 = 1.67 ton → step up to 2 ton, or insulate the roof and shade the wall to stay at 1.5 ton.
Quick guide: room size to AC tonnage (10 ft ceiling)
| Room size | Mild city | Bhopal | Raipur | Raipur, top floor + sun |
|---|---|---|---|---|
| 9 × 10 ft (90 sq ft) | 0.75 ton | 0.75 ton | 0.75 ton | 1 ton |
| 10 × 12 ft (120 sq ft) | 0.75 ton | 1 ton | 1 ton | 1.5 ton |
| 12 × 12 ft (144 sq ft) | 1 ton | 1.5 ton | 1.5 ton | 1.5 ton |
| 12 × 14 ft (168 sq ft) | 1.5 ton | 1.5 ton | 1.5 ton | 2 ton |
| 12 × 16 ft (192 sq ft) | 1.5 ton | 1.5 ton | 1.5 ton | 2 ton |
| 15 × 15 ft (225 sq ft) | 1.5 ton | 2 ton | 2 ton | 2 ton+ |
Two people, no extra heat sources. “2 ton+” means a larger unit or two ACs.
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Read more →FAQ
AC Tonnage Calculator: common questions
Is a 1.5 ton AC enough for a 150 sq ft room?
Inverter or non-inverter AC?
What do AC star ratings mean?
What happens if my AC is too big or too small?
How can I cool a top-floor room without a bigger AC?
Designing a home that stays cooler?
Ceiling design, insulation, shading and lighting all change how hard your AC works. Plan them together with our designers.
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