In recent decades direct numerical simulations of liquid-gas flows with interface capturing/tracking method have made great progress. But to address new configurations that contain highly deformed interfaces, a question arises about the validity of the obtained results. Usually, the only solution is to perform a mesh convergence analysis on a well-defined criteria/quantity, which is really costly. For complex simulations such as liquid jet atomization, there is no evidence that a complete resolution of the interface deformation has been achieved, even if these simulations are still very helpful to understand atomization mechanisms. Thus it stresses the need to find an indicator dedicated to the evaluation of the interface resolution quality (IRO). In this work, a definition for the IRO indicator is discussed and computed in two configurations: a two-phase homogeneous isotropic turbulence (HIT) and the Spray A configuration (liquid jet injection) from the Engine Combustion Network. The first configuration is used as a reference to ensure the pertinence of the resolution indicator in an academic scenario, where the convergence of the main features of the flows is assured. Regarding the second configuration, the IRO statistics such as probability density function (PDF) and average values of the IRO are shown to assess its usefulness in a complex configuration for different Weber and Reynolds numbers.