Kilocalories to Kilojoules Converter

Exactly 1,000 thermochemical calories, or 4,184 joules, make one kilocalorie. A food label that prints calorie, often with a capital letter, means this unit rather than the small calorie of physics.

Food energy on packaging, diet plans, restaurant menus and sports nutrition is stated in kilocalories. Physiology and nutrition research also reports energy expenditure in the same unit.

Kilocalories convert to kilojoules by the exact factor 4.184, and to joules by 4,184, with no rounding. Since a kilowatt-hour is 3.6 megajoules, one kilocalorie is a little over 0.00116 kilowatt-hours.

The standard mistake is to treat the label's calorie as the small calorie and conclude that food holds far less energy than it does. The label unit is one thousand small calories.

The kilocalorie is the label unit, the calorie is its one-thousandth in physics, and the kilojoule is the metric equivalent at 4.184 kilojoules each. A diet figure and a physics figure therefore need different units before they can be compared.

One kilojoule is exactly 1,000 joules, and the symbol is kJ. It is the joule multiple that food packaging commonly prints, with energy shown in kilojoules beside kilocalories, and chemistry uses it for reaction energies.

Nutrition panels, exercise machines and dietary advice report energy in kilojoules wherever the metric system is used. Materials and fuel data, such as energy content per kilogram, are tabulated in kilojoules as well.

The step from kilojoules to megajoules divides by exactly one thousand, so nothing is lost in the conversion. One kilocalorie equals 4.184 kilojoules, which is how the two columns on a food label correspond.

A reader who compares a kilojoule figure with a kilocalorie figure as though they were the same number will misjudge the energy by more than four times. The label's two columns state one amount in two units.

Kilojoules and kilocalories are the two energy columns on a food label, and the kilojoule figure is the larger number because one kilocalorie is 4.184 kilojoules. Megajoules take over where kilojoule figures become long, as they do for fuels.