Divine Hindu Calendar

Source: The New Bhagavad Gita by Koti Sreekrishna and Hari Ravikumar (A visual poetry edition of the Bhagavad Gita).

According to Surya Siddhanta, the Hindu calendar is cyclical and not linear.
Let us take a look at it from earth years.
To start with,
1) 365 days = 1 earth year
2) 1 earth year = 1 morning and 1 night of God (6 months being morning for them that is Uttarayanam and the other 6 months being night for them that is Dakshinayanam) = 1 Divine Day
3) 360 earth years = 1 Divine Year
4) 12000 Divine Years = 1 Maha Yuga (that is 360 X 12000 = 4.32 million earth years)
5) 1 Mahayuga = 4 Yugas
            a) Satya Yuga (also called Krita Yuga)
            b) Tretha Yuga
            c) Dwapara Yuga
            d) Kali Yuga
6) 1 Brahma Morning is called a Kalpa (1000 Mahayugas) and 1 Brahma Night is another Kalpa
    So, 2 Kalpas = 1 Day of Brahma
    So, 1000 Mahayugas = Morning of Brahma
    Another 1000 Mahayugas = Night of Brahma (Refer B. Gita 8:17-19, B. Gita 9:7)
    after which everything dissolves.
7) Brahma's life = 100 Brahma Years

More on Maha Yuga
Source: http://www.dharmakshetra.com/articles3/Time%20Measurements%20described%20in%20the%20Vedas.htm


Maha Yugas

The smallest cycle is called a maha yuga. A maha yuga is 4,320,000 human years. 

Each maha yuga is subdivided into the following four ages, whose lengths follow a ratio of 4:3:2:1:

Satya Yuga (also called Krita Yuga)
Span                         - This first age is 1,728,000 human years

Known as                  - The Golden Age or age of Truth

Qualities of this age    -  virtue reigns supreme

Human Stature           - 21 cubits 

Life  Span                  - A lakh of years

Death                        - death occurs only when willed

Treta Yuga

Span                         -  This second age is 1,296,000 human years
Known as                  -  The Silver Age
Qualities of this age    -  three quarters virtue and one quarter sin
Human Stature           -  14 cubits
Life  Span                  -  10,000 years


Dvapara Yuga

Span                         -   This third age is 864,000 human years
Known as                  -  The Bronze Age 
Qualities of this age    -  one half virtue and one half sin
Life  Span                  -  1,000 years

Kali Yuga -  Age, we are presently living in.  

Span                         -   The fourth and last age is 432,000 human years
Known as                  -  The Iron Age 
Qualities of this age    -  one quarter virtue and three quarters sin
Human Stature           -  3.5 cubits
Life  Span                  -  100-120 years