A Kalpa is 14 manvantaras

Brahma Kalpa or a day of Brahma is consisting of a period of fourteen manvantaras, together with the period intervening between two Manus is equal in all to 1,000 mahayugas, or 4,320,000,000 solar Years. This figure is almost equal to age of Earth calculated by modern techeniques

Brahma, Period of life: The reigns of 14 Manus (embracing the duration of 944 mahayugas) equal 4,294,080, 000 years; and, adding to these the sandhis (transitional period), equal to 6 maha-yugas, or 25,920,000 years, the total of these reigns and interregnums of 14 Manus is 1,000 maha-yugas, which constitute a kalpa, or "day of Brahma," amounting to 4,320,000,000 solar years. As Brahma's "night" is of equal duration, one day and night of Brahma would contain8,640,000,000 solar years; and 360 such days and nights make a year of Brahma, containing 3,110, 040, 000, 000 solar years; while 100 such years of Brahma constitute the whole period of Brahma's age, comprising 311, 004, 000, 000, 000 years. A full life of Brahma is called Para. Half of the life of Brahma is now over.