18000 BTU to kW
Updated
Convert 18,000 BTU/hr to 5.275 thermal kW with a 1.5-ton equipment guide, EER examples, electrical planning, and focused FAQs.
Direct answer: 18,000 BTU/hr = 5.275 kW.
Quick converter
Kilowatts (thermal)
18,000 BTU/hr = 5,275.28 W of thermal capacity. Updates as you type.
18,000 BTU/hr equals 5.27527926 thermal kW, normally displayed as 5.275 kW. In practical HVAC language this is a 1.5-ton capacity, often chosen for one large room, a two-room zone, or a compact open plan. Thermal kW tells you how quickly the system moves heat; it does not say how many electrical kilowatts the compressor consumes.
The conversion is 18,000 x 0.00029307107 = 5.27527926 kW, or 5,275.28 W of cooling. At EER 11, the electrical example is 18,000 / 11 = 1,636.36 W, about 1.636 kW. At 230 V that running estimate is 1,636.36 / 230 = 7.1 A; the equipment nameplate MCA and MOCP remain the authority for conductors and protection.
Worked example
- 1. Start
18,000 BTU/hr
- 2. Apply the formula
18,000 x 0.00029307107
- 3. Round the result
18,000 BTU/hr = 5.275 kW
Practical guidance
Room scale and floor area
An 18,000 BTU/hr system is a rough starting guide for about 700–1,000 square feet in mild, average construction. That range can describe a big living room, a small apartment, or an open living-and-kitchen area, but a sunny top floor can need more while a shaded insulated space can need less. A load calculation decides the final capacity, so do not purchase from floor area alone.
Window, mini-split, or small split
Large 18K window units exist, and they can be a practical single-room choice when a wall opening and 115 or 230 V circuit are available. Ductless mini-splits at 18K are quieter and usually more efficient, while a small split system can serve connected rooms if airflow is designed well. Compare certified capacity at the design temperature rather than trusting a marketing size badge.
Efficiency changes the input
EER is a useful snapshot: EER 9 would require 18,000 / 9 = 2,000 W, while EER 13 would require 18,000 / 13 = 1,384.62 W. The EER-11 example sits between them at 1,636 W, so the same thermal 5.275 kW can have very different wiring and operating cost. Seasonal SEER2 reflects cycling and weather better than one EER point.
Voltage, heat pumps, and comfort
Some 18K window products are offered on 115 V, but many mini-splits use 230 V; check the exact model before planning a receptacle. An 18K heat pump can provide similar heating capacity, though cold-weather output and backup heat deserve separate review. Oversizing a humid-climate room can satisfy temperature quickly while leaving moisture behind, so sensible and latent loads both matter.
A concrete running-cost check
At the EER-11 input, eight hours at steady full-load operation is 1.63636 x 8 = 13.09 kWh. With an example tariff of $0.15/kWh, that is 13.09 x $0.15 = $1.96 before cycling, inverter modulation, taxes, and demand charges. Actual daily energy is often lower, but this transparent calculation helps compare an 18K unit with a neighboring 12K or 24K choice.
Common mistakes to avoid
- Calling 5.275 thermal kW the electrical draw
- Selecting an 18K unit from square footage without a load calculation
- Using estimated 7.1 A instead of MCA/MOCP
- Ignoring humidity and adjacent open rooms
18000 BTU to kW 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
What is 18,000 BTU/hr in kW?
It is 18,000 x 0.00029307107 = 5.27527926 thermal kW, rounded to 5.275 kW. That is heat-transfer capacity, not compressor input.
Is 18,000 BTU/hr one and a half tons?
Yes. Dividing by 12,000 gives 1.5 refrigeration tons. A nominal 1.5-ton label still needs a certified capacity check at the actual design condition.
How much does EER 11 use?
18,000 / 11 = 1,636 W, or about 1.636 electrical kW. A higher EER reduces input for the same rated capacity.
What current should I expect at 230 V?
The arithmetic estimate is 1,636 / 230 = 7.1 A. Treat that as a running example only; MCA, MOCP, startup behavior, and local code govern installation.
How many kWh does eight hours take?
At constant EER-11 input, 1.636 x 8 is about 13.09 kWh. Cycling, weather, and inverter speed can make actual consumption lower or occasionally higher.
What floor area can 18K cool?
About 700–1,000 square feet is rough mild-climate guidance for average construction. Sun, insulation, windows, ceiling height, and occupancy change the result, so a load calculation decides.
Can an 18K unit run on 115 V?
Some large window models do, while many 18K mini-splits are 230 V. Read the model nameplate and receptacle requirements instead of assuming from BTU size.
Is 18K better than 12K for a damp room?
Only if the load calls for the extra capacity. An oversized 18K can cycle off before dehumidifying, while a correctly selected 12K may be more comfortable; calculate sensible and latent load.
More size guides
Continue with the BTU to kW converter, compare BTU/hr to tons of refrigeration, or check the BTU to horsepower converter.