There are many different calculations about just how long a manvantara is—but all agree that it is in the millions of human years. A smaller figure sets the number of years at only 4,320,000, while a larger calculation came to 306,720,000 human years. Each day in the life of Brahma, or kalpa, consists of a thousand fourfold Yugas (caturyugas or mahayugas). Each manvantara consists of seventy-one fourfold Yugas (caturyugas), or 306,720,000 human years. There are fourteen manvantaras or “ages of Manu.” For more details and calculations based on the Vishnu Purana, see the discussion in chapter 2.