Matsyapurana 142.27

142.27

catvāri niyutāni syur varṣāṇi tu kaliryugam
dvātriṃśacca tathānyāni sahasrāṇi tu saṃkhyayā
etatkaliyugaṃ proktaṃ mānuṣeṇa pramāṇataḥ //

Satyayuga, Tretâ, Dvâpara and Kaliyuga taken collectively last for a period of 12,000 years of the Devas Now I shall tell you their age in the years of men The age of Satyayuga in the years of men is 1,728 000 years, of Tretâ 1 296 000 years, of Dvâpara 864,000 years and of Kaliyuga 432,000 years The period of the four yugas along with the duration of their Sandhyâs and Sandhyâṁśas have thus been described in the years of men The four ages passing for 71 times make one Manvantara—25 29