When you need this conversion
Air conditioners and heat pumps (rated in BTU/h in the US and kW elsewhere), furnaces and boilers, and HVAC load calculations.
Quick reference
- 5,000 BTU/h = 1.46536 kW
- 9,000 BTU/h = 2.63764 kW
- 12,000 BTU/h = 3.51685 kW (1 ton)
- 18,000 BTU/h = 5.27528 kW
- 24,000 BTU/h = 7.03371 kW (2 tons)
- 36,000 BTU/h = 10.5506 kW (3 tons)
Sizing a room
A common rule of thumb is about 20 BTU/h per square foot of living space for cooling, adjusted for climate, sun and insulation. A 500 ft² room needs about 10,000 BTU/h (2.93 kW). Get a proper Manual J or equivalent load calculation for whole-house systems.
Common mistakes
Comparing capacity with input power. Cooling capacity (kW) is usually 3–4 times the electrical input.
Treating BTU and BTU/h as the same. One is energy, the other power.
For the reverse, use kW to BTU/h.