Energy converter

Eight units of energy at once. A kilowatt hour is 3.6 million joules, and a food Calorie — the one on packaging — is a kilocalorie, 4,184 joules.

The calorie is the trap, and it is a capital letter. A calorie is 4.184 joules; a Calorie with a capital C, which is what food labelling means, is a kilocalorie — a thousand times larger. So a 250 Calorie snack is 250 kilocalories, about a million joules. European labels avoid the ambiguity by printing kJ alongside. The BTU is the other awkward one: several slightly different definitions exist, and the value used here is the international table BTU, which is the one heating and cooling equipment is rated in.