  We exploit offshell regions in the process $e^+e^-\rightarrow W^+W^-b\bar{b}$
to gain access to the top-quark width. Working at next-to-leading order in QCD
we show that carefully selected ratios of offshell regions to onshell regions
in the reconstructed top and antitop invariant mass spectra are,
\emph{independently} of the coupling $g_{tbW}$, sensitive to the top-quark
width. We explore this approach for different centre of mass energies and
initial-state beam polarisations at $e^+e^-$ colliders and briefly comment on
the applicability of this method for a measurement of the top-quark width at
the LHC.
