Convert Kilocalories to BTU

About converting Kilocalories to BTU

Kilocalories (kcal) and BTU (BTU) are both units of energy, so converting between them is a single multiplication: multiply your Kilocalories figure by 3.9657. Ten Kilocalories comes to 39.6567 BTU, and a hundred works out at 396.5667 BTU.

Rule of thumb: going from Kilocalories to BTU multiplies, so the figure always grows — one Kilocalory is already 3.9657 BTU. If your answer came out smaller, you have the conversion the wrong way round.

What is a Kilocalory?

A kilocalorie is a thousand small calories, and it is what people actually mean when they say "calories" about food. Every figure on a nutrition label, every count on a menu board and every target in a diet app is a kilocalorie, even where the label just prints "cal" — a 2,000-calorie day is 2,000 kcal, not 2,000 calories in the physicist’s sense. The convention of capitalising the food unit as Calorie was meant to mark that difference, but it survives mostly in textbooks. Most of the world prints both kJ and kcal on packaging; the United States prints calories alone, which keeps the ambiguity alive.

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 plain bagel runs to roughly 250 kilocalories, 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 Kilocalories converter, or browse all Energy converters.