 The study uses a cascading fragmentation model to simulate particle size distributions of plastic particles in the ocean, coastal waters and on the beach and compares the results to available observations in the Mediterranean Sea. The model quantifies the role of fragmentation on the marine plastic mass budget and allows for future comparison to observed PSD data to understand size-selective plastic transport in the environment. This article was authored by Mikhail L. A. Khandorp, Henkei Dykstra, and Eric van Sebill.