Joules can also be converted from calories, as calories are another unit of energy. There are 4.19 joules in every calorie. You can calculate joules by calculating the kinetic energy, or energy of motion, of an object.You can also calculate the joules by calculating the amount of work accomplished by a person or machine. Lastly, you can calculate joules by converting directly from a measurement in calories.n science, the joule is the unit of energy or work. It is a compound unit defined as 1 newton of force over a distance of 1 meter, or as the kinetic energy of a 1 kilogram mass moving at one meter per second.