As the application of nickel-based heat-resistant alloy, a difficult-to-cut material, increases in aerospace engine, gas turbine and automotive parts, tool wear is emerging as an important issue. In this paper, finite-element (FE) simulations and experimental approaches are presented to estimate the tool wear of coated tungsten carbide cutting tools in the orthogonal cutting of Inconel 718. A tool wear model depends strongly on the experimentally acquired wear rates, which are measured by cutting tests. A three-dimensional data-based measurement method was investigated, and the volume loss of the tools was obtained to measure the wear geometries accurately. FE simulations of the cutting process were performed to calibrate the tool wear model by predicting the tool–workpiece interface temperature and normal stress. The constants of the tool wear model, for which the temperature-dependent wear model and Usui’s wear model were applied, were determined by a hybrid approach using FE simulation and experimental results. The approach was validated by comparing the estimated values with the experimental data.