Kilojoules & calories: how to convert between them? Answered in 100 words or less

Kilojoules (kj) & calories (cal) are both used to measure the amount of energy in foods and drinks, the same as kilometres and miles are both used to measure distance.

In Australia kj is preferred however US TV shows (such as the biggest loser) and cardio equipment made overseas (such as treadmills) make it difficult to let go of cal completely. For this reason it's useful to be able to quickly convert between them if necessary.

1cal = 4.2kj. You can do a rough calculation of 'cal x 4 = kj', which will be close enough for most purposes.