BTU to kW Calculator

A BTU to kW calculator converts a BTU per hour rating into kilowatts. Multiply the BTU/hr figure by 0.00029307107, the exact conversion factor. At 12,000 BTU/hr, an air conditioner works out to 3.517 kW, so you can compare US-rated equipment with kW-rated specifications.

Last reviewed September 2026Method & sources Report an error

Power

3.517 kW

Breakdown
Power	3.517 kW

How to Calculate BTU to kW

Multiplying BTU per hour by 0.00029307107 gives the equivalent power in kilowatts. That is the exact conversion factor: the same BTU-to-watts factor, divided by 1,000 for kilowatts.

Example: 12,000 BTU/hr air conditioner

A 12,000 BTU/hr air conditioner: Power: 12,000 × 0.00029307107 = 3.517 kW

What Is BTU to kW?

A BTU to kW calculator converts a heating or cooling appliance's BTU per hour rating into kilowatts. It is useful for comparing US BTU-rated equipment (furnaces, boilers, air conditioners) against European or other metric-specified equipment, which is commonly rated in kW.

BTU to kW: Pros and Cons

Pros

Uses the exact conversion factor, not a rounded approximation
Useful for comparing a US BTU-rated appliance against a kW-rated metric specification
Works for any BTU/hr rating, from a small heater to a large commercial system

Cons

This is a rated capacity conversion, not the appliance's actual electrical power draw. That difference matters most for heat-pump-based equipment (air conditioners, heat pumps), which move heat rather than generate it directly
Doesn't distinguish heating output from cooling output. Both convert the same way, but they represent different equipment types

Frequently Asked Questions

How do I convert BTU to kW?

Multiply BTU per hour by 0.00029307107. A 12,000 BTU/hr unit equals 12,000 × 0.00029307107 = 3.517 kW.

How many kW is a 3 ton air conditioner?

About 10.55 kW. A 3 ton unit is 36,000 BTU/hr, and 36,000 × 0.00029307107 ≈ 10.55 kW.

How do I convert kW back to BTU?

Divide by 0.00029307107 (or multiply by about 3,412). 5 kW is about 5 ÷ 0.00029307107 ≈ 17,061 BTU/hr.

Is a European boiler's kW rating comparable to a US furnace's BTU rating?

Yes, for output capacity. kW and BTU/hr both measure power (energy per time), so converting between them lets you compare heating or cooling capacity directly, regardless of which region's equipment you're looking at.

Does this conversion account for efficiency?

No. This converts a stated capacity rating from one unit to another. It doesn't account for how efficiently a specific appliance converts fuel or electricity into that output, which is a separate efficiency rating (like AFUE for furnaces or SEER for air conditioners).

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