  In this paper we present a Lagrangian method that allows the physical degree
of freedom count for any Lagrangian system without having to perform neither
Dirac nor covariant canonical analyses. The essence of our method is to
establish a map between the relevant Lagrangian parameters of the current
approach and the Hamiltonian parameters that enter in the formula for the
counting of the physical degrees of freedom as is given in Dirac's method. Once
the map is obtained, the usual Hamiltonian formula for the counting can be
expressed in terms of Lagrangian parameters only and therefore we can remain in
the Lagrangian side without having to go to the Hamiltonian one. Using the map
it is also possible to count the number of first and second-class constraints
within the Lagrangian formalism only. For the sake of completeness, the
geometric structure underlying the current approach--developed for systems with
a finite number of degrees of freedom--is uncovered with the help of the
covariant canonical formalism. Finally, the method is illustrated in several
examples, including the relativistic free particle.
