The size of the Solar System can be understood on different scales depending on what boundary you consider.

• The distance from the Sun to the farthest planet, Neptune, is about 3 billion miles (4.5 billion kilometers), or roughly 30 astronomical units (AU), where 1 AU is the average Earth-Sun distance of 93 million miles (149 million kilometers)

• Beyond Neptune lies the Kuiper Belt, which extends roughly from 30 to 50 AU and contains dwarf planets like Pluto

• The heliosphere, defined by the reach of the solar wind, extends to about 122 AU from the Sun, marking a boundary called the heliopause where the solar wind meets interstellar space

• The outermost boundary of the Solar System is considered to be the Oort Cloud, a theoretical spherical shell of icy objects surrounding the Sun. It starts somewhere between 1,000 and 5,000 AU and extends out to about 100,000 AU (about 15 trillion kilometers or 9.3 trillion miles)

• Doubling the Oort Cloud's radius gives a rough diameter of the Solar System of about 200,000 AU, or 30 trillion kilometers (18.6 trillion miles), which is over 3 light years across

• In simpler terms, the Solar System's size approaches nearly 2 light years in diameter, equivalent to almost 12 trillion miles, if you consider the Oort Cloud as its boundary

Thus, while the planets orbit within a few billion miles of the Sun, the Solar System's full extent including the Oort Cloud spans an immense volume of space over thousands of times larger, reaching out to about 200,000 AU or several light years across. This vast scale makes the Solar System enormous compared to human scales but still tiny compared to distances to other stars