Neptune vs Earth
Neptune is 49,244 km across, almost four times Earth's diameter. About 57 Earths would fit inside it by volume.
| Object | Real size | Source | |
|---|---|---|---|
| NeptuneDiameter, averagePublished dimension. See the measurement record for scope, date and conversions. | 49,244 km30,599 mi | Mean diameter, calculated as twice the mean radius; excludes rings and atmosphere limb effects. NASA/JPL Solar System Dynamics Measurement recordSource checked | |
| EarthDiameter, averageMean radius 6,371.0084 km × 2, rounded to a mean diameter of 12,742 km. The circular drawing uses the mean, not equatorial, diameter. | 12,742 km7,918 mi | Mean diameter derived from mean radius; not equatorial diameter. Measurement recordSource checked |
What measurements does this comparison use?
The reference values used here are 49,244 km for Neptune (Diameter, average) and 12,742 km for Earth (Diameter, average). The table links to background sources; natural objects and manufactured variants can differ from these reference values.
How should I read the drawing?
Neptune spans about 3.9× as much as Earth across the longest side of each drawing. This is a linear scale comparison, not a comparison of mass or volume. For maps, the table reports area; doubling a map’s width and height multiplies its area by four.
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