  A scheme for calculating corrections to all orders to the entropy of any
thermodynamic system due to statistical fluctuations around equilibrium has
been developed. It is then applied to the BTZ black hole, AdS-Schwarzschild
black Hole and Schwarzschild black Hole in a cavity. The scheme that we present
is a model-independent scheme and hence universally applicable to all classical
black holes with positive specific heat. It has been seen earlier that the
microcanonical entropy of a system can be more accurately reproduced by
considering a logarithmic correction to the canonical entropy function. The
higher order corrections will be a step further in calculating the
microcanonical entropy of a black hole.
