How big is the Moon compared to the Earth?

The Moon is the only natural satellite of the Earth. When you see the Moon way up in the sky, it’s not easy to get a sense of perspective about how big the Moon really is. There are different results if we compare them in size, mass, volume, gravity, etc. Let’s have a look.

The Earth is approximately 12,800 kilometers in diameter; about four times the diameter of the Moon which is 3,500 km in diameter. Or we can say that the size of the Moon is about a quarter of the Earth’s.

The surface area of the Earth is about 510 million square kilometers. On the other hand, the Moon is about 38 million square kilometers which is smaller than the continent of Asia. So the area of the Moon compared to the Earth is only 7.4%.

The Moon’s mass is 1/81 of the Earths. Mean density of the Moon is about 3.3 g/cm3, on the other hand the Earth has a mean density of 5.5 g/cm3, just 1.65 times of the Moon’s.

The volume of the Moon is 21.9 billion cubic km. Again, that sounds like a huge number, but the volume of the Earth is more like 1 trillion cubic kilometers. So the volume of the Moon is only 2% compared to the volume of the Earth.

The Moon’s surface gravity is about one sixth of the Earth's. Gravity at equator is 9.81 m/s2 for the Earth and 1.62 m/s2 for the Moon.

As a summary, the Earth is bigger than the Moon approximately 4 times in diameter, 13 times in surface area, 81 times in mass, 2 times in mean density, 46 times in volume and 6 times in surface gravity.