A local flux expansion method has been proposed for estimating the strike point position for the advanced divertor configuration on MAST Upgrade tokamak. The paper discusses the application and assesses the performance of the technique on a long-legged divertor plasma configuration on an operating device – the DIII-D tokamak. A comparison of the spatial location of the outer strike point estimated with the flux expansion method against the plasma boundary reconstruction and divertor diagnostics on DIII-D tokamak is reported. A good agreement with the equilibrium reconstruction and diagnostic data is achieved with respect to estimation of the spatial location of the outer strike point for the long-legged divertor plasma discharge.