The Bengali calendar (Bengali বঙ্গাব্দ Bônggabdo or বাংলা সন Bangla Shôn, Assamese: Vaskar), is the traditional calendar used in Bangladesh and eastern regions of India in the state of West Bengal, and Tripura. The calendar is based on the solar year. The year begins on Pôhela Boishakh, which falls between April 13 and April 15.