Pandora in Avatar is depicted as almost Earth-sized but slightly smaller, with lower gravity.

Basic size comparison

  • In franchise reference material and fan analyses, Pandora is often given a diameter of about 11,400 km, while Earth’s diameter is about 12,742 km.
  • That makes Pandora roughly 90% the size of Earth by diameter, which corresponds to about three-quarters of Earth’s volume.

Gravity and what it implies

  • Pandora is usually described as having about 80% of Earth’s gravity , meaning objects and people would weigh less there than on Earth.
  • To get this, sources suggest Pandora has about 72% of Earth’s mass , which fits with a slightly smaller, somewhat less dense world.

“Almost as large as Earth”

  • Franchise notes and discussions summarize it this way: Pandora is “almost as large as Earth” but is a moon of the gas giant Polyphemus, with gravity about 20% lower than Earth’s.
  • Visually and ecologically, this lets the setting show huge floating mountains and large fauna while still feeling Earth-like in climate and scale.

TL;DR: In Avatar canon and semi-canon discussions, Pandora is roughly 90% of Earth’s diameter, about 70–75% of its mass, and has about 80% of Earth’s surface gravity.

Information gathered from public forums or data available on the internet and portrayed here.