  We quantify the one-shot entanglement cost of an arbitrary bipartite state,
that is the minimum number of singlets needed by two distant parties to create
a single copy of the state up to a finite accuracy, using local operations and
classical communication only. This analysis, in contrast to the traditional
one, pertains to scenarios of practical relevance, in which resources are
finite and transformations can only be achieved approximately. Moreover, it
unveils a fundamental relation between two well-known entanglement measures,
namely, the Schmidt number and the entanglement of formation. Using this
relation, we are able to recover the usual expression of the entanglement cost
as a special case.
