How many galaxies are in the observable universe?
Guess before you scroll — the answer is below
The answer
2,000,000,000,000 galaxies
Roughly 2T.
Estimates put the observable universe at around 2 trillion galaxies. Each holds tens or hundreds of billions of stars. There are more stars in the observable universe than grains of sand on every beach on Earth, by a factor of thousands.
How to get close to this number
This is an exponent question, so reason in powers of ten. A deep-field image of a tiny patch of apparently empty sky contains thousands of galaxies; multiply by how many such patches tile the whole sky and you get a total in the hundreds of billions to trillions. That extrapolation from a sampled patch is literally how the estimate is made.
The comparison in the explanation is the one worth holding: more stars in the observable universe than grains of sand on every beach on Earth, by a factor of thousands. Both quantities are unimaginable, and they differ by three orders of magnitude — which is the recurring lesson that "astronomically large" is a range, not a category.
Two caveats are built into the question. "Observable" means the region whose light has had time to reach us, which is a limit on our knowledge rather than on the universe. And the estimate has moved substantially as instruments improved, generally upward as fainter galaxies became detectable — so this figure describes what we can currently see, not what is there.
Where this number comes from
| Source | NASA / Hubble Deep Field analyses |
|---|---|
| Figure refers to | 2024 |
| Last checked | |
| Unit | galaxies |
Numbers move. If this one has drifted from its source, let us know.
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