What is the life span of Lord Brahma according to Vedas?

Question

In my childhood, I had read about the life span of Brahma. can someone please enlight this topic?

Answer 1

Hinduism had their own scale of measuring mass, length and time, and they have done this to both extremes. Time can be measured to very small units as well as to humongous scales.

Quoting Hindu Units of Time|Wiki and BG 8.17,

• 1 human fortnight (15 days) = 1 day (light) or night of the Pitṛs
• 1 human month (30 days) = 1 day (light) and night of the Pitṛs
• 30 days of the Pitṛs = 1 month of the Pitṛs = (30 × 30 = 900 human days)

• 12 months of the Pitṛs = 1 year of the Pitṛs = (12 months of Pitṛs × 900 human days = 10800 human days)

  The lifespan of the Pitṛs is 100 years of the Pitṛs (= 36,000 Pitṛ days = 1,080,000 human days = 3000 human years)

• 12000 Deva Years = Life Span of Devas = 1 Mahā-Yuga.

• 1000 Mahā-Yugas = 1 Kalpa = 1 day (day only) of Brahma

  (2 Kalpas constitute a day and night of Brahma, 8.64 billion human years)

• 30 days of Brahma = 1 month of Brahma (259.2 billion human years)

• 12 months of Brahma = 1 year of Brahma (3.1104 trillion human years)
• 50 years of Brahma = 1 Parārdha
• 2 parardhas = 100 years of Brahma = 1 Para = 1 Mahā-Kalpa (the lifespan of Brahma)(311.04 trillion human years)

In short as per Hindu traditions,

The life span of any Hindu deva spans nearly (or more than) 4.5 million years and the lifespan of Brahma is 311.04 trillion human years.

SideNote: Age of Universe is estimated to be 13.8 billion years, nowhere close to the lifetime of Brahma. It's probably a few days old.