PURPORT

The kalpa is explained in Bhagavad-gita. Sahasra-yuga-paryantam ahar yad brahmano viduh. One day of Brahma is called a kalpa. A yuga, or maha-yuga, consists of 4,320,000 years, and one thousand such maha-yugas constitute one kalpa. The author of Sri Caitanya-caritamrta says that if one does not take advantage of the Krsna consciousness movement of Sri Caitanya Mahaprabhu, he cannot be delivered for millions of such kalpas.