  Quantifying coherence has received increasing attention, and considerable
work has been directed towards finding coherence measures. While various
coherence measures have been proposed in theory, an important issue following
is how to estimate these coherence measures in experiments. This is a
challenging task, since the state of a system is often unknown in practical
applications and the accessible measurements in a real experiment are typically
limited. In this Letter, we put forward an approach to estimate coherence
measures of an unknown state from any limited experimental data available. Our
approach is not only applicable to coherence measures but can be extended to
other resource measures.
