Planets - Calculate Surface Areas

Calculator for the approximate surface areas of Sun, Moon, Earth and the planets in square kilometers, square miles and compared to each other. The common unit for large surface areas is square kilometers, km². Of those, Earth has more than 500 million, whereas the Sun has more than 6 trillion.

Square kilometers:
Square miles:
Surface Areas		km² mi² Earth surfaces Jupiter surfaces Sun surfaces
Moon:
Mercury:
Venus:
Earth:
Mars:
Jupiter:
Saturn:
Uranus:
Neptune:
Pluto:
Sun:

Round to   0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15   decimal places.

Please enter one value, the other values will be calculated.

Example: Moon has more than twice the surface area of Pluto, but only half of that of Mercury.

A planet's surface is determined by its size and shape. The shape is that of an oblate spheroid. However, rocky planets like Earth are generally not significantly flattened, meaning they closely resemble a sphere. Size is defined by the radius, which is the distance from the center to the surface. Surface area increases with the square of the radius. Thus, doubling the radius results in four times the surface area, assuming the shape remains constant. Rocky planets, Mercury, Venus, Earth and Mars in our solar system, possess a solid surface that defines a precise boundary. Gas planets, Jupiter, Saturn, Uranus and Neptune, likely have a solid core surrounded by a vast, opaque atmosphere that grows increasingly thin toward the outside. Because a precise boundary is difficult to pinpoint in this case, their radius and surface area depend on the definition used. This definition is based on a specific pressure, usually one bar. Venus, Earth and Mars also have atmospheres, but these are generally not included when calculating surface area. This calculator treats the atmosphere as irrelevant to surface area for rocky planets, while factoring it in for gas planets. Surface details such as mountains, valleys, and craters are ignored.
Earth is the largest rocky planet in our solar system, but other stars may well host larger rocky planets, known as super-Earths. These can have up to twice Earth's radius, resulting in four times Earth's surface area.

Last updated on 07/30/2026. Author: Jürgen Kummer

Calculators for Planets and Astronomy

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