A Galaxy in Your Hand: Comparing Earth’s Sand to the Stars Above

The famous comparison that there are more stars in the universe than grains of sand on Earth is scientifically accurate, but the scale of the difference is even more mind-blowing than most people realize.

According to current astronomical and geological estimates in 2025, there are roughly 10,000 stars for every single grain of sand on Earth.

1. Counting the Sand on Earth

To estimate the sand, scientists look at the total volume of the world’s beaches and deserts.

• The Math: Researchers calculate the total coastline of the world (about 372,000 miles) and multiply it by average beach width and depth. Then they add the volume of the world’s deserts (like the Sahara).
• The Grain: An average grain of sand is about 0.5 mm in diameter. You can fit about 8,000 grains into a single cubic centimeter.
• The Total: The widely accepted estimate is approximately 7.5 * 10¹⁸grains of sand.
  • In plain English: That is 7.5 quintillion grains (7.5 billion billion).

2. Counting the Stars in the Universe

We cannot count every star individually, so astronomers use a “census” method: they count the number of galaxies in a specific patch of sky and multiply that by the average number of stars per galaxy.

The Galaxy Count

For years, the estimate was 2 trillion galaxies. However, recent data from the New Horizons mission (beyond Pluto) and the James Webb Space Telescope (JWST) in 2024–2025 suggest the sky is “darker” than we thought, leading to a refined estimate of hundreds of billions of galaxies in the observable universe.

Stars per Galaxy

A typical galaxy, like our Milky Way, contains between 100 billion and 400 billion stars. Some “giant” elliptical galaxies have 100 trillion stars, while “dwarf” galaxies have only a few million.

The Total

Using a conservative average of 100 billion stars per galaxy across 200 billion to 2 trillion galaxies:

• The Estimate: Between 10²²and 10²⁴ stars.
• In plain English: This is roughly 1 septillion stars (a 1 followed by 24 zeros).

Note on the “Observable” Universe: These star counts only include the part of the universe we can see (light has had time to reach us). Because the universe is expanding, the total universe is likely much larger, and possibly infinite, meaning the number of stars could be truly endless.

4. Where the Comparison Breaks

If you want to flip the script, there is one place where Earth wins: Atoms.

While there are more stars than grains of sand, there are more atoms in a single grain of sand than there are stars in the entire observable universe.

• Stars in Universe ~ 10²⁴
• Atoms in one grain of sand ~ 10¹⁹ to 10²⁰(Okay, Earth almost wins here—actually, you’d need about 10,000 grains of sand to have more atoms than there are stars in the sky!)