The duration of the Dvapara millennium equals 2,400 years; and that of the Kali millennium is 1,200 years of the demigods

Expressions researched:
"The duration of the Dvapara millennium equals 2,400 years; and that of the Kali millennium is 1,200 years of the demigods"

Srimad-Bhagavatam

SB Canto 3

The duration of the Dvapara millennium equals 2,400 years; and that of the Kali millennium is 1,200 years of the demigods.

SB 3.11.19, Translation and Purport

The duration of the Satya millennium equals 4,800 years of the years of the demigods; the duration of the Treta millennium equals 3600 years of the demigods; the duration of the Dvāpara millennium equals 2,400 years; and that of the Kali millennium is 1,200 years of the demigods.

As aforementioned, one year of the demigods is equal to 360 years of the human beings. The duration of the Satya-yuga is therefore 4,800 x 360, or 1,728,000 years. The duration of the Tretā-yuga is 3,600 x 360, or 1,296,000 years. The duration of the Dvāpara-yuga is 2,400 x 360, or 864,000 years. And the last, the Kali-yuga, is 1,200 x 360, or 432,000 years.