  Currently the entanglement of formation can be calculated analytically for
mixed states in a $(2\otimes2)$-dimensional Hilbert space. For states in higher
dimensional Hilbert space a closed formula for quantifying entanglement does
not exist. In this regard only entanglement bounds has been found for
estimating it. In this work, we find an analytical expression for evaluating
the entanglement of formation for bipartite ($2\otimes d$)-dimensional mixed
states.
