Air Conditioner BTU Calculator
Work out how many BTU an air conditioner needs for a room or a whole home, with the suggested AC size and monthly electricity cost.
Add more rooms to size a whole home.
11,200 BTU
m
m
m
W
16 m²Suggested AC: 12,000 BTU
Result
Cooling needed
11,200 BTU/h
16
m² floor
3.28
kW
0.93
tons
Suggested air conditioner
- Bedroom12,000 BTU
How it adds up ▸▾
- Floor area × room factor+11,200
- High ceiling0
- Extra people0
- Under the roof0
- Appliances0
Electricity cost (estimate)
h
฿/u
Per month (30 days)
฿403
96 kWh
For the suggested units (12,000 BTU in all). SEER is on the energy label — a เบอร์ 5 unit is usually 15–25. Assumes the compressor runs about 60% of the time.
How the BTU is worked out
- BTU/h = floor area (m²) × room factor, the rule of thumb Thai installers use. The factor is 700–800 for a bedroom, 750–850 for a living room, 800–900 for an office, 900–1,000 for a kitchen and 950–1,100 for a shop. The lower figure is for a shaded room, the higher one for a room in the sun.
- Then it adds more for a ceiling above 2.7 m, each person beyond two (+600 BTU), a room right under the roof (+15%), and appliances that give off heat (1 W = 3.412 BTU/h).
- The suggested size is the next common size up: 9,000, 12,000, 15,000, 18,000, 24,000 BTU and so on. An AC that is too small runs flat out and never cools; one far too big cools in short bursts and leaves the room damp.
Good to know
- This is an estimate. Big windows, poor insulation or a room open to others need more; ask an installer to check.
- 12,000 BTU/h = 1 ton of cooling = about 3.5 kW.
- The electricity cost is a rough guide; real use depends on the thermostat setting and the weather.
- Everything is calculated in your browser; nothing you enter is sent anywhere.