What is the approximate age of the universe?

The approximate age of the universe is 13.8 billion years.

Scientists estimate this age by combining measurements of cosmic expansion with observations of the cosmic microwave background, the faint afterglow of the hot early universe. The leading cosmological model, known as Lambda-CDM, uses data from missions including NASA’s Wilkinson Microwave Anisotropy Probe and the European Space Agency’s Planck spacecraft.

The estimate describes the time since the hot, dense early state associated with the Big Bang. It is not the age of the oldest individual object measured by simply adding its distance in light-years, because space itself has expanded while light has travelled. Distances and look-back times therefore require a cosmological model.

The age of the universe is sometimes confused with the age of the Solar System, which is about 4.6 billion years. It is also an estimate rather than a direct timestamp. Small differences between published values can result from different data sets and assumptions, but 13.8 billion years is the standard rounded figure.