According to NASA, Pluto has a mass that is equal to 0.0022 that of Earth's, or 1.3 sextillion kilograms. This makes Pluto considerably less massive than, not just all eight planets, but also several of the moons in the solar system.
According to Space.com, Pluto has a diameter of 1,430 miles. This is equal to only 20 percent of Earth's diameter and, taken with the dwarf planet's low mass, establishes its density at only just over 2 grams per cubic centimeter. This is only 40 percent of Earth's density, suggesting that Pluto has a dramatically different composition and internal structure.