From elementary mathematics to symbolic and historical information, Kalacakra and The Tibetan Calendar presents the contents of the most recent Tibetan calendars. This work, which is crucial for comprehending the first chapter of the Kalacakra Tantra, translates and clarifies the pertinent passages from the Tantra's renowned commentary, the Vimalaprabha, and recounts the history of the calendrical systems in the Tantra. Since the 15th century, when lamas from various lineages sought to make sense of the mathematical systems they had received from India, the principal calendars in use in Tibet have remained mostly intact. These adjustments were made to correct ever-more-obvious mistakes. This book examines the primary systems still in use today, evaluating their precision and contrasting them with the procedures outlined in the original Tantra.