Twelve thousand years make a cycle. Four such cycles, taken a thousand times, make a Kalpa which measures one day of Brahman.
युगं द्वादशसाहस्रं कल्पं विद्धि चतुर्युगम्। दशकल्पशतावृत्तमहस्तद् ब्राह्ममुच्यते॥