The conversion
1 ton of cooling = 12,000 BTU per hour = about 3.5 kW. To convert BTU to tons, divide by 12,000. To convert tons to BTU, multiply by 12,000.
| BTU per hour | Tons | kW (approx.) | Typical room |
|---|---|---|---|
| 9,000 | 0.75 | 2.6 | Very small room |
| 12,000 | 1 | 3.5 | Up to about 150 sq ft |
| 18,000 | 1.5 | 5.3 | About 150 to 220 sq ft |
| 24,000 | 2 | 7.0 | About 220 to 300 sq ft |
| 30,000 | 2.5 | 8.8 | Large lounge or office |
| 36,000 | 3 | 10.6 | Halls, shops |
| 48,000 | 4 | 14.1 | Halls, showrooms |
Reading Daikin model codes
The number in a Daikin model code is its capacity class in tenths of a kW. A class 35 unit (such as FTXC35DV1B) is about 3.5 kW, or 1 ton. Class 50 is about 1.5 ton, and class 60 is about 2 ton in everyday terms.
The exact rated figure can differ from the round number. Daikin rates the FTXC50DV1B at 17,400 BTU/h, which sellers call 1.5 ton. Our product pages show both the tonnage and the official BTU/h figure.
Which size do you need?
For a normal room, plan on about 1 ton for every 150 sq ft. Go one size up for top floors, sunny west walls, or rooms that are busy with people or equipment.
Frequently asked questions
How many tons is 18,000 BTU?
1.5 ton. Divide 18,000 by 12,000.
Is 12,000 BTU the same as 1 ton?
Yes. One ton of cooling is 12,000 BTU per hour, about 3.5 kW.
Is ton the weight of the AC?
No. Ton is a measure of cooling capacity, not weight. It comes from the cooling effect of melting one ton of ice over a day.
