Kalpa is a Sanskrit word (devanāgarī: कल्प) meaning a relatively long period of time (by human calculation) in Hindu and Buddhist cosmology. The concept is first mentioned in the Mahabharata. The definition of a kalpa equalling 4.32 billion years is found in the Puranas (specifically Vishnu Purana and Bhagavata Purana). A kalpa is also said to be a day of Brahmā, and consists of a thousand cycles of four yugas or ages.In the Theosophical teaching of cycles of evolution a Kalpa is the time of existence of our Planetary Chain, that is, the seven rounds.
Brahmā’s months are said to be 30 of his days long and his year is 12 of his months; his lifetime is said to be 100 of his years.
The Maha-Kalpa embraces the whole lifetime of Brahmā, which is of 100 years (1 year are 12 of his months, which consist of 30 days each). For this reason it is called the "Age of Brahmā".
- Helena Petrovna Blavatsky, Collected Writings vol. XIII (Wheaton, IL: Theosophical Publishing House, 1982), 301.
- Kalpa at Theosopedia