  We present an exact quantization condition for the time independent solutions
(energy eigenstates) of the one-dimensional Dirac equation with a scalar
potential well that gives only two `effective' turning points (defined by the
roots of $V(x)+mc^2=\pm E$) for a given energy $E$ and satisfies $\min
V(x)+mc^2\geq 0$. This result generalizes the previously known non-relativistic
quantization formula and preserves many physically desirable symmetries,
besides, attaining the correct non-relativistic limit. Numerical calculations
demonstrate the utility of the formula for computing accurate energy
eigenvalues.
