BTU/hr to kW Calculator
Convert BTU/hr to kilowatts for HVAC sizing. Live calculator using the exact 1 kW = 3,412.142 BTU/hr conversion.
Common conversions
| Input | Result |
|---|---|
| 6,000 BTU/hr | 1.76 kW |
| 8,000 BTU/hr | 2.34 kW |
| 10,000 BTU/hr | 2.93 kW |
| 12,000 BTU/hr | 3.52 kW |
| 18,000 BTU/hr | 5.28 kW |
| 24,000 BTU/hr | 7.03 kW |
| 36,000 BTU/hr | 10.55 kW |
| 60,000 BTU/hr | 17.58 kW |
The math behind it
- kW = 18000 / 3412.142
- kW ≈ 5.275
Everything you need to know
BTU/hr is the traditional US unit for describing how much heat an air conditioner, furnace, or heat pump can move each hour. Converting it to kW puts HVAC equipment on the same scale as electrical loads, energy models, and international spec sheets.
BTU/hr vs kW: output, not input
A BTU/hr rating describes thermal output, the rate of heat moved into or out of a space, not the electricity the equipment consumes. A 24,000 BTU/hr air conditioner moves about 7.03 kW of heat, but its compressor might only draw 1.5 to 2 kW of electricity to do it. That gap is the point of air conditioning: a well-designed heat pump moves several times more thermal energy than the electrical energy it consumes, described by its COP or SEER rating.
Common AC unit sizes: 6,000 to 24,000+ BTU/hr
Window and portable AC units are typically sold in standard sizes: 6,000 BTU/hr (about 1.76 kW, small bedrooms), 8,000 to 10,000 BTU/hr (2.34 to 2.93 kW, medium rooms), 12,000 BTU/hr (3.52 kW, large rooms or small studios), and 18,000 to 24,000 BTU/hr (5.28 to 7.03 kW, open-plan living areas or small apartments). A rough sizing guide is about 20 BTU/hr per square foot of floor area, adjusted for ceiling height, sun exposure, and climate.
How BTU/hr relates to tons
Tons of refrigeration and BTU/hr describe the same thing at different scales: 12,000 BTU/hr equals exactly 1 ton, or 3.51685 kW. Large commercial and industrial cooling equipment is usually rated in tons once the capacity climbs past a few units of window AC, which is why a 5-ton rooftop unit (60,000 BTU/hr, 17.58 kW) sits in a different catalogue than a 12,000 BTU/hr mini-split, even though both use the same underlying unit of power.
Common applications
A 12,000 BTU unit ≈ 3.5 kW thermal. Compare against the room's heat-loss kW to confirm capacity matches design temperature.
Furnaces are rated in BTU/hr input. Convert to kW for side-by-side comparison against electric heat-pump output.
Process chillers are spec'd in kW; building chillers often in BTU/hr or tons. Converting all loads to a single unit prevents sizing errors.
Window units are commonly sold in 6,000, 8,000, 10,000, 12,000, 18,000, and 24,000 BTU/hr sizes. Converting to kW makes it easy to compare cooling output against a room's calculated heat load in kW.
Common mistakes
A 7 kW thermal AC only draws about 1.6 kW electrical at SEER 15. Don't add the cooling rating to your panel load total.
BTU is energy, BTU/hr is power. A '12,000 BTU' AC unit is really rated 12,000 BTU/hr; dropping the '/hr' causes confusion when comparing to kWh energy bills.
Oversized units cool a room quickly but cycle on and off too often, leaving humidity uncontrolled. Matching BTU/hr to room size, roughly 20 BTU/hr per sq ft, gives better comfort than maxing out capacity.
BTU/hr ratings aren't just for air conditioners; furnaces and heat pumps use the same unit for heating output, so context matters when comparing two 24,000 BTU/hr specs.
Frequently asked questions
How many kW is 12,000 BTU/hr?+
About 3.52 kW, using 12,000 ÷ 3,412.142. That's also exactly 1 ton of refrigeration.
What's the difference between BTU and BTU/hr?+
BTU is a unit of energy, like a kWh; BTU/hr is a unit of power, energy per unit time, like a kW. HVAC equipment is rated in BTU/hr, not BTU, even though people often drop the '/hr' in conversation.
How many kW is a 24,000 BTU AC unit?+
About 7.03 kW of cooling output. Electrical input is much lower, typically 1.5-2 kW depending on the unit's SEER rating.
What size window AC do I need for a bedroom?+
Most bedrooms (100-300 sq ft) use a 6,000 to 10,000 BTU/hr unit, roughly 1.76 to 2.93 kW of cooling. Larger open-plan rooms need more.
How does BTU relate to tons of refrigeration?+
12,000 BTU/hr equals exactly 1 ton of refrigeration, or about 3.51685 kW. A 36,000 BTU/hr unit is 3 tons.
Does a higher BTU rating mean higher electricity use?+
Not necessarily. BTU/hr measures cooling output, not electrical input. A high-SEER 24,000 BTU unit can use less electricity than a low-efficiency 18,000 BTU unit.
Is BTU/hr used for heating as well as cooling?+
Yes. Furnaces, boilers, and heat pumps are rated in BTU/hr for heating output the same way air conditioners are rated for cooling output.
How many kW is a 60,000 BTU/hr furnace?+
About 17.58 kW of heating output, using 60,000 ÷ 3,412.142.
Why is the conversion factor 3,412.142 and not a round number?+
It comes from the exact definition of the BTU in terms of joules, converted through watts to kW. It's precise rather than rounded, which matters for larger commercial calculations.