The thermal energy within an object is measured in joules. This unit is obtained from other basic units, such as mass, time and length. The unit was named in honor of Prescott Joule. A calorie is also a measure of heat.
A calorie can be defined as the heat energy needed to increase the temperature of a single gram of water by one degree Celsius. A single calorie is equal to 4.185 joules. The energy content of food is typically measured in calories. Heat differs from temperature. An object's temperature relates to how cold or hot it is. It is measure in Celsius.