Heat is defined as the form of energy that is transferred across the boundary of a system at a given temperature to another system at a lower temperature by virtue of the temperature difference between the two system.
Mathematically,
Heat = Energy
Dimensional formula of Energy = M1L2T-2
Putting these values in above equation we get,
Dimensional Formula of Heat = M1L2T-2
SI unit of Heat is Joule (J)