In Singapore, a bedroom up to about 13 m² needs a 9,000 BTU (1 HP) aircon, a master bedroom of 14 to 18 m² needs 12,000 BTU, and a living room of 19 to 27 m² needs 18,000 BTU. Living and dining in one space usually takes 18,000 + 12,000, not one 24,000.
Type of home?
Aircon size guide
Usual sizes for a Singapore home with a standard ceiling. West sun, a top floor or big windows can push a room up one size.
| Room size | Room | Aircon |
|---|---|---|
| up to 13 m² | Bedroom, study | 9,000 BTU · 1 HP |
| 14 – 18 m² | Master bedroom | 12,000 BTU · 1.5 HP |
| 19 – 27 m² | Living room | 18,000 BTU · 2 HP |
| Living + dining | HDB, condo | 18k + 12k |
| 28 m² and up | Large living | 24,000 BTU+ |
How the calculator works
The calculator multiplies the floor area by 650 BTU per square metre, adjusts for sun, ceiling height, people and appliances, then rounds up to a standard aircon size.
- Start with 650 BTU for every square metre of floor.
- Add 10% each for west sun, a top floor or big windows, and 15% for a ceiling of 3 m or more.
- Add 600 BTU for each person above two, 4,000 BTU for an open kitchen and 1,000 BTU for a PC or home office.
- Round up to the next size: 9,000, 12,000, 18,000 or 24,000 BTU.
- Living and dining in one space needing more than 18,000 BTU get two units: 18,000 + 12,000, then 24,000 + 12,000, at most 18,000 + 18,000. One outdoor unit runs about 38,000 BTU across two indoor units.
- The living room gets its own system when its aircon runs most days, or when living and dining are at least twice the master bedroom. The other rooms share one system of up to 4 indoor units.
Common questions
How many systems do I need?
Ask how often the living room aircon runs. Most days, or living + dining twice your master bedroom? Give it its own system, e.g. System 3 for the bedrooms + System 2 for living and dining. If not, one system can cover the home.
Is a bigger aircon better?
No. It cools fast, stops before drying the air, and leaves the room cold and clammy.
BTU or HP?
Same thing, two scales: 9k ≈ 1 HP, 12k ≈ 1.5 HP, 18k ≈ 2 HP, 24k ≈ 2.5 HP.
System 3 or 4?
The number is how many indoor units share one outdoor unit. Five or more: usually two systems.