Incalculable kalpa (skt. asamkhyeya-kalpa, Wyl. bskal pa grangs med pa) is the longest great kalpa. Despite its name, it corresponds to a precise length of time: in the Abhidharma counting system, ’incalculable’ (skt; asmakhyeya, Wyl. grangs med pa) refers to the largest number, ten to the power sixty.
In the Mahayana tradition, it takes a bodhisattva three incalculable kalpas, from the moment he sets out on the path to enlightenment by first giving rise to bodhichitta until finally reaching awakening.
In the Pali tradition the four intermediary kalpas that make a great kalpa are also called incalculable kalpas.