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Is Mercury Bigger than the Moon?

Last Reviewed and Updated on June 21, 2022

Mercury is the smallest planet in our Solar System. But how small is it exactly? Is Mercury bigger than the Moon? How does it compare to the moons of other planets in our Solar System? Read on and get the answers to these most interesting questions.

Is Mercury Bigger than the Moon?

When it comes to planets in our Solar System, Mercury is the smallest of them all. So how does its size compare to the Moon, the Earth’s only natural satellite?

So let’s look at Mercury vs Moon:

The diameter of Mercury is measured at 3,031.9 miles / 4,879.4 km.

The diameter of the Moon is 2,159 miles / 3,474.8 km.

When it comes to these two, Mercury is bigger than the Moon. But we do have more moons in our Solar System and Earth’s moon is only the 5th biggest of all known moons.

Which moons in our Solar System are bigger than Mercury?

Our moon is far from being the only one in our Solar System and it certainly isn’t the largest one.

This means there are moons in our Solar System that are bigger in size than Mercury is.

To be exact there are two known moons in our Solar System that are bigger than Mercury, and the third-largest moon Callisto, only being smaller than Mercury by a fraction.


Ganymede is the largest known moon in our Solar System. It is the moon orbiting Jupiter.

With its diameter of 3,273 mi / 5,268 km, it is quite a bit larger than Mercury. It is also only slightly smaller than the planet Mars! With the size that big, you might be wondering why it’s classified as a moon and not a planet. This is because it doesn’t meet one important criteria, it orbits Jupiter rather than orbiting the Sun.


Titan, the second-largest known moon in our Solar System orbits the planet Saturn.

It has a diameter of 3,199 miles / 5,149 km so it is another moon in our planetary system that surpasses Mercury by its size.

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