BTU to kW Calculator
Convert BTU/hr to kilowatts (and back). Includes tons of cooling conversion and quick reference table for all common AC sizes.
| BTU/hr | kW | Watts | Tons | Typical use |
|---|---|---|---|---|
| 5,000 | 1.47 | 1465 | 0.4 | Window AC (small room) |
| 8,000 | 2.34 | 2345 | 0.7 | Window AC (medium room) |
| 12,000 | 3.52 | 3517 | 1.0 | Window AC (large room) / 1-ton |
| 18,000 | 5.28 | 5275 | 1.5 | 1.5-ton central AC |
| 24,000 | 7.03 | 7034 | 2.0 | 2-ton central AC |
| 30,000 | 8.79 | 8792 | 2.5 | 2.5-ton central AC |
| 36,000 | 10.55 | 10551 | 3.0 | 3-ton central AC |
| 42,000 | 12.31 | 12309 | 3.5 | 3.5-ton central AC |
| 48,000 | 14.07 | 14067 | 4.0 | 4-ton central AC |
| 60,000 | 17.58 | 17584 | 5.0 | 5-ton central AC |
| 120,000 | 35.17 | 35169 | 10.0 | 10-ton commercial |
How to Use This Calculator
Choose your conversion direction
Select BTU/hr → kW if you know your HVAC equipment's BTU rating and want the kW equivalent. Select kW → BTU/hr if you have a power rating in kilowatts and need the BTU equivalent.
Enter your value
Type the BTU/hr or kW value you want to convert. For air conditioners, the BTU rating is printed on the unit's label and in the product specifications. Common residential sizes run from 5,000 BTU (small window unit) to 60,000 BTU (5-ton central system).
Use the presets
Click a preset scenario — 1-ton AC (12,000 BTU), 2-ton (24,000 BTU), 5-ton commercial (60,000 BTU), or 10 kW solar — to quickly see the conversion for common equipment sizes.
Read the results
Results show the converted value plus the equivalent in tons of cooling — a common HVAC sizing unit where 1 ton = 12,000 BTU/hr = 3.517 kW.
The Formula
A BTU (British Thermal Unit) is the heat energy needed to raise 1 pound of water by 1°F. BTU/hr is the rate of energy transfer — the same as power. The conversion factor 0.000293071 comes from the relationship between thermal and electrical energy units: 1 Wh = 3.412 BTU.
"Tons" of cooling comes from the original way air conditioners were compared to ice — one ton of cooling equals the heat absorbed by melting one ton (2,000 lbs) of ice in 24 hours.
Example
Sizing solar for air conditioning
A homeowner has a 3-ton central air conditioner (36,000 BTU/hr). They want to know how much solar capacity they need to run it.
Important: the BTU/hr rating of an AC is its cooling capacity, not its electrical consumption. A 36,000 BTU/hr AC with a SEER rating of 16 actually draws: 36,000 ÷ 16 = 2,250 watts (2.25 kW) of electricity. For solar sizing, use the electrical wattage, not the BTU rating.