What is the Sun's mass in kilograms?

The Sun’s mass is approximately 1.989 × 10^30 kilograms.

That enormous figure represents about 333,000 Earth masses and roughly 99.86% of all the mass in the Solar System. Most of the remaining mass is concentrated in Jupiter and the other planets, moons, asteroids, and comets.

The Sun accumulated its mass about 4.6 billion years ago when gravity collapsed a region of a giant molecular cloud. Material gathered into a dense central protostar, while leftover matter formed the rotating disk that became the planets. Once the core became hot and dense enough, hydrogen fusion began.

A common mix-up is confusing the Sun’s mass with its luminosity or energy output. The Sun converts about 600 billion kilograms of hydrogen into helium each second, but only about 4 billion kilograms of mass is converted directly into energy. Despite this ongoing loss, the Sun’s mass changes only slightly over human timescales.