The durations of the four Yugas is correctly found in the Vedic text known as Bhagavata Purana (Srimad Bhagavatam) and is accepted by all bonafide Vaishnava and Sanskrit scholars.

The durations of the four Yugas is correctly found in the Vedic text known as Bhagavata Purana (Srimad Bhagavatam) and is accepted by all bonafide scholars.

The Mayavadi Swami Sri Yukteswar Giri, the guru of  Paramahansa Yogananda's understanding of Vedic texts regarding yugas is considered bogus speculation according to Vaishnava scholars.

Srimad Bhagavatam or Bhagavata Purana, gives the correct measurements of yugas and was written over 5000 years ago.

The Viṣṇu Purāṇa Time measurement section of the Viṣṇu Purāṇa Book I Chapter III explains the above as follows:

4,800 divine years = 1,728,000 human years = 1 Satya Yuga.

3,600 divine years = 1,296,000 human years = 1 Treta Yuga.

2,400 divine years = 864,000 human years = 1 Dvapara Yuga.

1,200 divine years = 432,000 human years = 1 Kali Yuga.

12,000 divine year = 4 Yugas.

4 Yugas = 1 Mahā-Yuga = 4,320,000 human years

Brahma's day.

All 1000 Mahā-Yugas occur only during the day-time period of Brahma's day from sunrise to sunset, there are no Maha-yugas or living entities active in Brahma's night

1 Kalpa = 1 day-time of Brahma.
1 Kalpa = 1 night-time of Brahma.

2 Kalpas constitute a day and night of Brahma that equals 8 billion 640 million human years in length.

30 days of Brahma or 1 month of Brahma equals 259 billion 200 million human years.

12 months of Brahma or 1 year of Brahma equals 3 trillion 11 billion 400 million human years.

50 years of Brahma = 1 Parārdha (156 trillion 764 billion 160 million human years.

2 parardhas = 100 years of Brahma = 1 Para = 1 Mahā-Kalpa.

The lifespan of Brahma is 311 trillion 40 billion human years also according to Srimad Bhagavatam.

One day of Brahma is divided into 10000 parts called charaṇas.

Four Yugas

The four yugas which come one after the other are as follows (along with their durations):

The Four Yugas.

4 charaṇas (1,728,000 solar years) Satya Yuga.
3 charaṇas (1,296,000 solar years) Treta Yuga.
2 charaṇas (864,000 solar years) Dvapara Yuga.
1 charaṇas (432,000 solar years) Kali Yuga.