The observable universe is estimated to contain about 108010^{80}1080 atoms, often quoted as “somewhere between 107810^{78}1078 and 108210^{82}1082 atoms.” This is only for the observable part of the universe, not necessarily all that exists.

Quick Scoop

  • Most scientific estimates put the number of atoms in the observable universe at around 108010^{80}1080 atoms.
  • Some sources give a broader range from about 107810^{78}1078 up to 108210^{82}1082 atoms, depending on assumptions about galaxy counts, average masses, and composition.
  • These estimates come from:
    • Estimating how many galaxies and stars exist in the observable universe.
    • Estimating the average mass of those stars and other visible matter.
    • Converting that total mass into a number of atoms (mostly hydrogen).

Why It’s Only An Estimate

  • No one can count atoms directly; the number comes from large-scale measurements of mass, galaxy surveys, and cosmological models.
  • The figure applies only to what we can observe (roughly a 93-billion-light-year-wide region); if the full universe is larger or infinite, the total number of atoms could be far greater or even unbounded.

Fun Size Comparisons

  • A single human body has on the order of 102710^{27}1027 atoms, which is already a 1 followed by 27 zeros.
  • The universe’s estimate of around 108010^{80}1080 atoms is so huge that even a “googol” (1010010^{100}10100) is still larger; you would need an enormous number of universes like ours to reach a googol of atoms.

Mini FAQ Style Notes

  • Is the number changing over time?
    Nuclear reactions convert matter to energy and back in different forms, but the total number of atoms in the observable universe over cosmic timescales stays in roughly the same mind‑boggling ballpark in these estimates.

  • Why does the range vary so much between sources?
    Different estimates use different values for:

    • Number of galaxies (from ~101110^{11}1011 to a few 101210^{12}1012).
* Average mass per galaxy and fraction of matter that is in “ordinary” atoms versus dark matter and dark energy.

TL;DR: In everyday terms, there are on the order of a hundred quattuordecillion atoms (about 108010^{80}1080) in the observable universe—an almost unimaginably large but still finite number.

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