How Many BTU Are in a Ton of Cooling?
James S.Oct 3rd 20264 min read
The short answer
- How many BTU are in a ton? 12,000 BTU per hour of cooling. Not 12,000 BTU of weight, and not the heating number on a heat pump.
- The old lab definition is the heat required to melt one short ton of ice (2,000 lb) at 32°F in 24 hours. Latent heat of fusion is 144 BTU per pound: 2,000 × 144 ÷ 24 = 12,000 BTU/h.
- Half a ton is 6,000. Two tons is 24,000. Three tons is 36,000. Five tons is 60,000.
Where the 12,000 comes from
People ask how many BTU are in a ton because a contractor speaks in tons and a carton speaks in BTU. They are the same cooling rate in two units. A British thermal unit is a quantity of heat. Air conditioners are rated in BTU per hour, which is how fast that heat can be moved.
The refrigeration ton was set long before mini splits. Melting ice absorbs 144 BTU for each pound. A short ton is 2,000 pounds, so melting that ice takes 288,000 BTU. Spread across 24 hours, the rate is 12,000 BTU/h. That is why every later multiple is just the ton count times 12,000. A ton of cooling is not the shipping weight of the outdoor unit.
Tons to BTU, from a half ton to five tons
| Cooling tons | BTU/h | What to do with it |
|---|---|---|
| 0.5 | 6,000 | Half a ton. Not a mini split we sell. |
| 0.75 | 9,000 | Smallest ductless head in this lineup. |
| 1 | 12,000 | The definition. One exact ton. |
| 1.5 | 18,000 | DUET outdoor cooling, split across two heads. |
| 2 | 24,000 | Largest single indoor head we sell. |
| 3 | 36,000 | 3 × 12,000. Not a head in this catalog. |
| 5 | 60,000 | 5 × 12,000. A whole-house load, not one head here. |
“Of cooling,” “of AC,” and “of refrigeration” are the same 12,000 BTU/h rule. “Of heating” is the trap. A heat pump’s heating nameplate is often a different BTU/h, and it falls further when the outdoor air is cold. The BTU-to-tons sizing guide maps these rates onto rooms. This page is the definition.
Where one ton sits in this lineup
The 19 SEER2 12,000 BTU mini split is a full 12,000 BTU/h, so it is one ton of cooling, on 115V, published for up to about 550 square feet under typical conditions. The 17 SEER2 model in that class publishes 11,500 BTU of cooling, just under a ton, and up to about 280 square feet. The 9,000 BTU mini split is 0.75 ton and 23 SEER2. The 24,000 BTU mini split is 2 tons on 230V. Its sheet does not publish SEER2.
From the spec sheet
- 12,000 BTU/h cooling · 1 ton
- 19 SEER2
- 115V
- Up to 550 sq ft
- Heating nameplate 12,200 BTU/h
From the spec sheet
- 9,000 BTU/h cooling · 0.75 ton
- 23 SEER2
- 115V
- Up to 400 sq ft
- Heating nameplate 9,500 BTU/h
The ton is the label. The room still needs a number. Open the Size Finder, then compare 9,000, 12,000, and 24,000 BTU.
Do not turn a heating number into tons
When the word ton misleads
- Dividing the heating BTU/h by 12,000 does not give you the cooling ton the room was sized for.
- A class name on a carton can be rounder than the tested cooling. The 17 SEER2 12,000 BTU class is 11,500 BTU/h.
- Three tons (36,000) and five tons (60,000) are real arithmetic. They are not indoor heads we sell. Two closed rooms use DUET, not one oversized head.
- Refrigerant work and the electrical circuit belong to a licensed HVAC technician and a licensed electrician. Warranty is 5-year compressor / 1-year parts, and a non-professional install can put it at risk.
Use the ton, then size the room
Multiply or divide by 12,000, then run the room in the Size Finder. Sun, ceiling height, insulation, and climate move the load off the round ton. Oversizing a small room is also how a system fails at drying the air. The piece on why sizing controls humidity is the longer explanation.
FAQ
Common questions
How many BTU are in a ton of cooling?
12,000 BTU per hour. Multiply any ton count by 12,000. Two tons is 24,000 BTU/h. Three tons is 36,000. Five tons is 60,000.
How many BTU are in a ton of air conditioning?
The same 12,000 BTU/h. AC, refrigeration, and cooling tons all use that rate. Heating output on a heat pump is a separate figure.
Is a 12,000 BTU mini split one ton?
The 19 SEER2 system is rated 12,000 BTU/h, so yes, one ton, up to about 550 square feet. The 17 SEER2 system publishes 11,500 BTU.
Does Classic America sell a 3-ton or 5-ton mini split?
No. The largest single head is 24,000 BTU/h, which is 2 tons, on 230V, and that sheet does not publish SEER2. DUET is 18,000 BTU/h of cooling across two 9,000 BTU heads, 24 SEER2 non-ducted.
