All things · Giant Planets

Neptune: how big is it?

Neptune is about 49,200 km. In everyday terms, that is ≈ 3.9 Earths.

Size

49,200 km

In metres

4.92 × 10⁷ m

Everyday comparison

≈ 3.9 Earths

Chapter

Giant Planets

Did you know?

The windiest planet in the solar system, with gusts of over 2,000 km/h.

How it compares

• About 3.9× bigger than Earth (12,700 km).
• About 2.4× smaller than Saturn (116,000 km).

Other things of a similar size

• The Moon 3,470 km
• Mars 6,780 km
• Earth 12,700 km
• Saturn 116,000 km
• Jupiter 140,000 km
• Earth → Moon distance 384,000 km

Sizes are rounded, typical values drawn from standard reference sources, including NIST/CODATA physical constants and NASA's planetary fact sheets. Real objects vary; see About for how sizes are chosen.