The Big Bang is estimated to have occurred about 13.8 billion years ago , which is taken as the age of the universe.

A bit more detail

  • Modern measurements (for example, of the cosmic microwave background by missions like Planck) place the Big Bang at roughly 13.8 billion years in the past , with an uncertainty of only a few tens of millions of years.
  • In practical terms, when people ask “when did the Big Bang occur?”, cosmologists answer with this age, since it marks the beginning of the expansion of the observable universe and of cosmic time as we can meaningfully define it.

You can think of it as the “time zero” of our universe’s history: run the cosmic expansion backwards, and all matter and energy converge to an extremely hot, dense state about 13.8 billion years ago.

Information gathered from public forums or data available on the internet and portrayed here.