what is the duration of each yuga

As per srimad bhagavatham 3-11-19 

Note: The years mentioned bellow are years of demigods.
1 year of humans on earth is 1 day for demigods.

Satya yuga - 4,800 years.
Treta yuga - 3600 years.
Dvapara yuga - 2,400 years.
Kali yuga - 1,200 years.

calculate these years to human years.