Convert Kilojoules to BTU

About converting Kilojoules to BTU

Kilojoules (kJ) and BTU (BTU) are both units of energy, so converting between them is a single multiplication: multiply your Kilojoules figure by 0.9478. Ten Kilojoules comes to 9.4782 BTU, and a hundred works out at 94.7817 BTU.

Rule of thumb: going from Kilojoules to BTU divides, so the figure always shrinks — it takes about 1.0551 Kilojoules to make a single BTU. If your answer came out bigger, you have the conversion the wrong way round.

What is a Kilojoule?

A kilojoule is a thousand joules, the size at which the joule becomes practical for everyday quantities. In Australia and New Zealand it is the primary unit on nutrition labels — food energy is quoted in kilojoules first, with calories relegated to a secondary figure or dropped entirely — so shoppers there think about daily intake in thousands of kilojoules rather than thousands of calories. It is also the working unit of chemistry, where reaction and bond energies are tabulated per mole. European labels print both kJ and kcal, which is why the same packet carries two different numbers for the same food.

What is a BTU?

The BTU is the heat needed to raise one pound of water by one degree Fahrenheit — and there is no single BTU. Water takes slightly different amounts of heat to warm depending on the temperature it starts from, so several definitions exist (thermochemical, International Table, 39 °F, 59 °F, 60 °F and others), differing from one another by a fraction of a percent. This converter uses one common value, so treat the result as convention-dependent rather than absolute. In the US it is the unit of heating and cooling capacity, though air conditioners are really rated in BTU per hour and the "per hour" is routinely dropped in marketing.

To put both in perspective: a slice of bread carries roughly 300 kilojoules, while a wooden kitchen match releases roughly one BTU.

The converter above updates as you type, and the table lists common values for quick reference. Need the opposite direction? Use the BTU to Kilojoules converter, or browse all Energy converters.