The age of Brahma is 100 divine years, which equals about 311.04 trillion human years. Although Lord Brahma is one of the three chief Hindu gods, he is not immortal. To know the age of Lord Brahma in human years, one needs to understand the concepts of Kalpa, Chaturyuga, and Mahayuga.
Who is Lord Brahma?
In Hinduism, Brahma, Vishnu, and Mahesh, collectively known as Trimurti or Tridev, are the holy Hindu trinity. These are the three main Hindu gods, who control the universe’s creation, sustenance, and destruction respectively. They are the manifested forms of Brahman, the Supreme Being. These three gods are considered to be the most powerful of all gods.
Lord Brahma is the creator of the universe. He is not worshipped individually because of a curse. He is mainly worshipped in the form of the Trinity. Many of his characteristics resemble the Vedic god, Prajapati. He does not incarnate on Earth as do Lord Vishnu and Lord Shiva. He is the least popular of the three gods.
Please read The Time in Hinduism to understand the concept of time in Hinduism.
The Divine Year:
Hindus believe that gods live on another planet named Svarga, and their time is different than that of humans. In Hindu cosmology, a divine year is a year of gods. One day of gods is equal to approximately one human year, and one divine year equals 360 human years.
Calculation of Age of Brahma:
Per the Puranas, Lord Brahma has a lifespan of 100 years. Each year has 360 days. One day of his life consists of 2 Kalpas (one day and one night), and each Kalpa consists of 1000 Maha-Yugas.
One Maha-Yuga consists of four Yugas (Chaturyugas), viz. Satya, Treta, Dwapara, and Kali.
Satya Yuga – 4800 divine years = 1728000 solar years
Treta Yuga – 3600 divine years = 1296000 solar years
Dwapara Yuga – 2400 divine years = 864000 solar years
Kali Yuga – 1200 divine years = 432000 solar years
Therefore, one Maha-Yuga has 4,320,000 solar years.
Each Kalpa has 1000 Maha-Yugas. Therefore, in human years each Kalpa has 4,320,000 * 1000 = 4,320,000,000 (4.32 billion) human years.
One day of his life consists of 2 Kalpas (one day and one night). Therefore, one day of Lord Brahma equals 8.64 (4.32 * 2) billion solar years.
Therefore, Lord Brahma’s life in human years is 100 * 8,640,000,000 * 360 = 311,040,000,000,000 (311.04 trillion years).
Currently, 50 years of Lord Brahma’s life have passed, and we are on the first day of the 51st year.