18000 BTU to Tons
Updated
Convert 18,000 BTU/hr to 1.5 refrigeration tons with room context, equipment choices, EER electricity math, and installation FAQs.
Direct answer: 18,000 BTU/hr = 1.5 tons.
Quick converter
Tons of refrigeration
18,000 BTU/hr = 5,275.28 W of thermal capacity. Updates as you type.
18,000 BTU/hr is exactly 1.5 refrigeration tons because a refrigeration ton is defined as 12,000 BTU/hr. That capacity commonly appears on a ductless 1.5-ton system, a large window conditioner, or a small split serving an open living area. Tonnage describes heat removal; it is not a motor rating and does not predict the utility bill by itself.
The direct formula is 18,000 / 12,000 = 1.5 tons. Converting the same capacity gives 5.27527926 thermal kW. For an EER-11 example, 18,000 / 11 = 1,636 W, about 7.1 A at 230 V, and 1.636 x 8 = 13.09 kWh for eight steady hours; use the nameplate MCA/MOCP for electrical work.
Worked example
- 1. Start
18,000 BTU/hr
- 2. Apply the formula
18,000 / 12,000
- 3. Round the result
18,000 BTU/hr = 1.5 tons
Practical guidance
What one and a half tons looks like
A rough 700–1,000 square foot range can fit a 1.5-ton load in moderate weather, such as a well-insulated apartment or a medium open plan. It is only a screening range: glass, roof exposure, people, cooking, and infiltration can move the load substantially. A load calculation decides whether 18K is right.
Equipment found in this class
A 1.5-ton ductless mini-split is a common choice for quiet zone control, while large window units can cool one broad room without ducts. Compact central or packaged systems may use the same nominal capacity, but coil match, airflow, and duct leakage affect delivered performance. Read the rated BTU/hr at the relevant outdoor temperature.
Why EER changes the bill
At EER 9, an 18K system needs 2,000 W; at EER 11 it needs 1,636 W; at EER 13 it needs 1,385 W. All three still provide the same nominal 1.5 tons under the rating condition, so tonnage alone cannot compare running cost. SEER2 and the equipment's input table add seasonal context.
Voltage and heating mode
18K window air conditioners can be found in both 115 V and 230 V versions, whereas ductless outdoor units commonly use 230 V. Heat-pump versions reverse the cycle for heating, but low-temperature capacity and defrost behavior should be checked separately. A 230 V current estimate is only a planning clue; MCA and MOCP control the branch circuit.
Humidity, zones, and price example
Oversizing a humid room may reach the thermostat quickly and remove too little moisture. If steady EER-11 operation lasted eight hours, 13.09 kWh at $0.15/kWh would cost about $1.96. A variable-capacity 18K system or two smaller zones may control comfort better when rooms have different exposures.
Common mistakes to avoid
- Interpreting tons as equipment weight
- Equating 1.5 tons with 1.5 electrical kW
- Choosing a breaker from an estimated 7.1 A
- Skipping latent-load and duct checks
18000 BTU to Tons chart
| BTU/hr | kW | Tons | HP |
|---|---|---|---|
| 9,000 | 2.638 | 0.75 | 3.537 |
| 12,000 | 3.517 | 1 | 4.716 |
| 18,000 | 5.275 | 1.5 | 7.074 |
| 24,000 | 7.034 | 2 | 9.432 |
| 30,000 | 8.792 | 2.5 | 11.79 |
| 36,000 | 10.551 | 3 | 14.149 |
| 48,000 | 14.067 | 4 | 18.865 |
| 60,000 | 17.584 | 5 | 23.581 |
Common questions
How many tons is 18,000 BTU/hr?
18,000 / 12,000 = 1.5 refrigeration tons exactly. The word ton here denotes cooling capacity, not mass.
What is 1.5 tons in thermal kW?
Multiply 18,000 by 0.00029307107 to get 5.27527926 kW, normally shown as 5.275 kW. Electrical input will be lower or higher depending on efficiency.
How many watts at EER 11?
The example is 18,000 / 11 = 1,636 W. It is a useful comparison number, while the product nameplate supplies the actual rated input.
What is the 230 V running current?
1,636 W divided by 230 V is about 7.1 A. Installation still follows MCA, MOCP, conductor sizing, and local electrical rules.
How much energy is eight hours?
At steady EER-11 input, 1.636 kW x 8 h equals approximately 13.09 kWh. Cycling and weather mean a real meter reading will differ.
What rooms suit 1.5 tons?
A 700–1,000 square foot open area is a rough moderate-climate guide. A load calculation decides after accounting for envelope, sun, people, and adjacent rooms.
Is a 1.5-ton heat pump always 18,000 BTU/hr?
Nominal sizing usually points to 18,000 BTU/hr, but certified heating and cooling capacities vary with outdoor temperature. Check the performance table rather than relying on the label.
Could two 9K heads replace one 18K unit?
They can when separate rooms need independent control, but the outdoor unit and minimum modulation must support that combination. Zoning improves distribution only when the load and layout justify it.
More size guides
Continue with the BTU to kW converter, compare BTU/hr to tons of refrigeration, or check the BTU to horsepower converter.