How many kilojoules is 1 BTU?

1 BTU (International Table) equals 1.05505585262 kJ. This is the most commonly used definition of BTU and is the standard in HVAC and heating equipment ratings.

How do I convert BTU to kJ manually?

Multiply the BTU value by 1.05506. For example, 1,000 BTU × 1.05506 = 1,055.06 kJ. To convert kJ back to BTU, divide by 1.05506.

What is the difference between BTU and kJ?

Both measure energy. BTU (British Thermal Unit) is defined as the heat needed to raise 1 pound of water by 1°F. Kilojoule is the SI metric unit equal to 1,000 joules. The kJ is preferred in science and most countries outside the US.

Why are there different BTU definitions?

The BTU has several definitions based on different temperature intervals (IT, thermochemical, 39°F, 60°F). The IT BTU (1.05505585262 kJ) is the modern standard used in engineering and HVAC, and is what this converter uses.

What is 10,000 BTU in kilojoules?

10,000 BTU equals 10,550.6 kJ. This is a common air conditioner capacity used for rooms around 450–550 square feet.

Is BTU per hour the same as BTU?

No. BTU is a unit of energy; BTU/hr (BTU per hour) is a unit of power. This converter handles BTU (energy), not BTU/hr (power). For power, use a watts or kilowatts converter.

BTU to Kilojoules Converter

Name: BTU to Kilojoules Converter
Availability: InStock
Author: Nham Vu

Enter BTU to get kilojoules instantly, or enter kJ to reverse-convert. 1 BTU (IT) = 1.05506 kJ.

Converter

Energy in BTU (British Thermal Units)

Result in kilojoules (kJ)

Reverse: kilojoules to BTU

Energy in kilojoules (kJ)

Result in BTU

Reference Table

BTU Kilojoules (kJ)

1 BTU 1.05506

5 BTU 5.27528

10 BTU 10.5506

50 BTU 52.7528

100 BTU 105.506

500 BTU 527.528

1,000 BTU 1,055.06

5,000 BTU 5,275.28

10,000 BTU 10,550.6

50,000 BTU 52,752.8

100,000 BTU 105,506

1,000,000 BTU 1,055,056

Formula: kJ = BTU × 1.05506 • BTU = kJ ÷ 1.05506

Summary

Enter BTU to get kilojoules instantly, or enter kJ to reverse-convert. 1 BTU (IT) = 1.05506 kJ.

How it works

Enter a BTU value in the top field to see the kilojoule equivalent instantly.
Use the reverse field to enter kilojoules and convert back to BTU.
Click "Copy" next to any result to copy the value to your clipboard.
Check the reference table for common BTU-to-kJ pairs used in heating and HVAC.
The IT (International Table) BTU is used: 1 BTU = 1.05505585262 kJ.

Use cases

Convert furnace or boiler BTU ratings to kilojoules for international specs.
Translate HVAC equipment BTU capacity to kJ for metric datasheets.
Convert food energy values from BTU (rare) to kilojoules for nutrition labels.
Check heating appliance output in kJ when comparing to metric-rated units.
Convert natural gas or propane energy content from BTU to kilojoules.
Verify heat pump ratings given in BTU against kJ-based efficiency figures.

Frequently Asked Questions

Last updated: 2026-07-01 · Reviewed by Nham Vu