The calorie, also known as the capital letter C, is most commonly used in food labeling, which is equivalent to the energy required to raise 1 kg 15 degrees Celsius water by one degree at a standard atmospheric pressure, 1 calorie = 4.185 joules.
Small card, also known as cal, is more common in scientific research documents. 1000 small card =1big card.
Kilogram is a unit of weight. There is no conversion relationship between them.