BTU, watts, kW and tons converter
Type a capacity in any unit; the other three update as you type, with the room size that capacity cools.
12,000 BTU/h is
3,516.85 W, 3.5169 kW, 1 ton
- 3,516.85 W
- 3.5169 kW
- 1 ton
On ENERGY STAR's room chart, 12,000 BTU/h covers a room up to 550 sq ft (51.1 m²) with average sun and two people.
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Common sizes and the room each one cools
The sizes are the capacities, in whole thousands of BTU/h, with at least 20 certified models in ENERGY STAR's list of room air conditioners or at least 500 in its list of mini-split heat pumps (counted on 2026-11-09). The last column reads the ENERGY STAR room chart backwards for an average room with two people and an 8 ft ceiling. The chart is written for room air conditioners; for a mini-split it is a guide to the same room, not a rule. For shaded or sunny rooms and more people, see how many square feet each AC size cools.
| BTU/h | kW | Tons | Common as | Room it covers |
|---|---|---|---|---|
| 5,000 | 1.47 | 0.42 | window or portable | 150 sq ft (13.9 m²) |
| 6,000 | 1.76 | 0.50 | window or portable | 250 sq ft (23.2 m²) |
| 8,000 | 2.34 | 0.67 | window or portable | 350 sq ft (32.5 m²) |
| 9,000 | 2.64 | 0.75 | mini-split | 400 sq ft (37.2 m²) |
| 10,000 | 2.93 | 0.83 | window or portable | 450 sq ft (41.8 m²) |
| 12,000 | 3.52 | 1.00 | window or portable, mini-split | 550 sq ft (51.1 m²) |
| 14,000 | 4.10 | 1.17 | window or portable | 700 sq ft (65.0 m²) |
| 18,000 | 5.28 | 1.50 | window or portable, mini-split | 1,000 sq ft (92.9 m²) |
| 24,000 | 7.03 | 2.00 | window or portable, mini-split | 1,500 sq ft (139.4 m²) |
| 30,000 | 8.79 | 2.50 | mini-split | 2,000 sq ft (185.8 m²) |
| 36,000 | 10.55 | 3.00 | mini-split | beyond the chart |
| 48,000 | 14.07 | 4.00 | mini-split | beyond the chart |
The factors
A BTU per hour is a rate of heat, like a watt. NIST Special Publication 811 fixes the International Table BTU at 1.055 055 852 62 kJ, so one BTU per hour is 0.293 071 W and 1 kW = 3,412.14 BTU/h. NIST also gives the ton of refrigeration: 12,000 BTU per hour, or 3.516 853 kW.
Heater makers often round the factor: King Electric's sizing sheet says (BTU = WATTS X 3.412)
, which agrees with the exact value to three decimals. The
converter uses the exact NIST figure and shows BTU/h and watts to at most two decimals, kilowatts and tons to at most four.
How many BTUs are in 1.5 ton AC?
18,000 BTU/h. One and a half tons is 1.5 × 12,000 BTU/h, which is 5,275.28 W or 5.2753 kW. On the ENERGY STAR chart that capacity covers a room up to 1,000 sq ft (92.9 m²) with average sun and two people.