Uranus vs Neptune
Uranus (51,118 km) is 1.03× the size of Neptune (49,528 km).
Neptune is 97% of the height of Uranus. The gap between them is 1,590 km (5,216,535 ft).
The comparison in numbers
| Thing | Size | In feet | Measured as |
|---|---|---|---|
| Uranus | 51,118 km | 167,709,974 ft | diameter |
| Neptune | 49,528 km | 162,493,438 ft | diameter |
What the scale shows
Uranus (51,118 km) is 1.03× the size of Neptune (49,528 km). The gap between them is 1,590 km (5,216,535 ft). Both are planets & moons, so the figures describe the same kind of thing.
Draw both on one baseline and the smaller one fills 97% of the frame while the larger one runs to the top. The two are close enough that the difference is easy to see side by side.
Read the rest — 8 more sections
What each figure means
The figure for Uranus is its diameter (equatorial diameter). The figure for Neptune is its diameter (equatorial diameter).
Crossing them
At a jet's 900 km/h, Uranus's 51,118 km would take 2.4 days and Neptune's 49,528 km would take 2.3 days.
In people: Uranus is 30,069,412 adults of 1.7 m tall, Neptune is 29,134,117.6. By size Uranus is 4th of the 16 planets & moons on this site and Neptune is 5th, so 1 place separates them in the ranking.
How to read these two figures
Before trusting any comparison, check what each number measures. Uranus is given as a diameter, equatorial diameter. Neptune is given as a diameter, equatorial diameter. Both are diameter figures, so putting them on one baseline is a like-for-like comparison, although the exact individual or convention still matters.
Worlds are listed by diameter. Gas giants are not round, so equatorial diameter is used for them and mean diameter for the rest. All figures are rounded from published mission data.
Where the pair sits among all the sizes here
Across all 86 things on this site, Uranus is number 4 from the top and Neptune is number 5. No other item falls between them, so in this collection they are direct neighbours.
Because the collection spans 13 mm up to 1,392,700 km, a ratio of 107,130,769,231× from smallest to largest, the position of a pair says a lot: both sit in the upper third of the list.
What the length ratio hides
A length ratio of 1.03× is easy to picture, but area and volume grow faster than length. If two objects had exactly the same shape, Uranus would have about 1.07× the surface or footprint of Neptune, and about 1.1× the volume. These two are not the same shape, so treat the figures as an upper bound for an imaginary scaled copy, not as a measurement of either one.
The drawing above shows length only. Neptune is drawn 97% as tall as Uranus, but the equivalent share of footprint would be only 93.9%, which is why the smaller one looks even slighter than the numbers alone suggest.
Time to cross each one
Light travels at 299,792,458 m/s, so it crosses Uranus (51,118 km) in 171 milliseconds and Neptune (49,528 km) in 165 milliseconds. A jet at 900 km/h would take 2.4 days for the larger and 2.3 days for the smaller.
These times assume a straight line and constant speed, which no real crossing has, but they turn a number in metres into something the body understands. At any fixed speed the travel times keep the same 1.03× ratio as the sizes.
The same figures in other units
Uranus measures 51,118 km, which is 167,709,974 ft or 31,763.3 miles. Neptune measures 49,528 km, which is 162,493,438 ft or 30,775.27 miles.
The difference between them is 1,590 km (5,216,535 ft). In kilometres the smaller one is 49,528 against 51,118, so the 1.03× ratio holds in every unit; only the numbers on the ruler change.
Questions people ask about this pair
Which is bigger, Uranus or Neptune?
Uranus is bigger. At 51,118 km it is 1.03× the size of Neptune, which is 49,528 km.
How many times does Neptune fit along Uranus?
Less than twice: Neptune is 97% of the size of Uranus, so one fits with 1,590 km to spare.
Are the two figures measured the same way?
Yes in kind: both are diameter figures. Uranus is equatorial diameter; Neptune is equatorial diameter.
How does the gap look in people?
Taking an adult of 1.7 m, Uranus is about 30,069,412 people tall and Neptune is about 29,134,117.6. The gap of 1,590 km is 935,294 people.
Where do the numbers come from?
Each item has its own page that names the measurement and links to the Wikipedia article it was taken from. Some figures are rounded, and animals vary from one individual to the next, so treat them as representative values rather than records for every case.
How the sizes are taken. Each figure says what it measures — height, length, diameter or elevation — and for which individual or convention. Everything is drawn standing upright on one baseline so a single scale holds, including things that are long rather than tall. Values come from the linked Wikipedia article for each item.