AC tonnage calculator for Indian rooms, offices and double height spaces
A 150 sq ft bedroom needs a 1 tonne AC and a 250 sq ft living room needs 2 tonnes.
Works out the cooling load from room size, space type, ceiling height, sun exposure, floor, glazing and occupancy, then recommends the AC tonnage sold in India. Double height living rooms and lobbies are handled on the occupied zone rather than the full volume.
How it is worked out: BTU per hour = area x load per sq ft x height factor x sun x floor x glazing, plus extra people; tonnes = BTU / 12,000
Indicative figures, last updated 10 September 2026. Check them against the local source before relying on them.
Questions people ask
What tonnage AC for a 12 by 14 room?
About 1.5 tonnes for a normal bedroom or living room with a 10 ft ceiling on a middle floor. A sunny west-facing room on the top floor pushes it to 2 tonnes.
How is a double height living room different?
Cooling load does not rise in step with the ceiling. Only the lower occupied zone needs to be comfortable, so the calculator adds roughly 45% of the extra height rather than all of it, and allows for warm air collecting at the top. A 20 ft high living room of 360 sq ft works out near 3.7 tonnes, not the 5.3 a straight volume calculation would give.
Why does a gym or restaurant need more than a bedroom?
People, equipment and kitchens all add heat. A gym is taken at 135 BTU per hour per sq ft against 80 for a bedroom, and a restaurant at 125, because bodies and cooking dominate the load.
Common values
| Space | Area | Cooling load | AC size |
|---|---|---|---|
| Bedroom | 150 sq ft | 12,000 BTU/h | 1 tonne |
| Living room | 250 sq ft | 21,250 BTU/h | 2 tonne |
| Home office or cabin | 150 sq ft | 13,500 BTU/h | 1.5 tonne |
| Meeting room | 200 sq ft | 21,000 BTU/h | 2 tonne |
| Lobby or reception | 300 sq ft | 28,500 BTU/h | 2.5 tonne |
| Gym | 300 sq ft | 40,500 BTU/h | 3.5 tonne |
Built by 256 GRAYS, an interior architecture and 3D visualisation studio in Mumbai.