To calculate tsunami forces on coastal structures, the wave type in front of the coast is of great importance. Hence this paper aims to find ways to predict the type of tsunami wave breaking. Based on literature review, video footage, analytical reasoning and numerical modelling (SWASH) it can be concluded that both the continental shelf slope (alpha_2) and the bay geometry (beta) have a significant influence on the transformation of a tsunami wave near the coastline. After conducting 1D and 2DH wave simulations, a distinction is made in three types of tsunami waves; a non-breaking front (surging), a breaking front (plunging) and an undular bore breaking front (spilling). Tsunami waves transform into these three wave types for a steep continental shelf, an intermediate sloped continental shelf, and a gentle sloped continental shelf respectively. A new tsunami breaker parameter (xi_tsunami) is proposed to predict the type of wave at the coastline in a quantitative way.