How wide is Earth?

Compared with things you know

• About 3.7 times as wide as the Moon (3,475 km)
• Saturn including its rings (280,000 km) is about 22 times as wide.
• The Sun (1,391,400 km) is about 109 times as wide.

Earth dimensions

Which diameter is meant

Earth is not a perfect sphere, so there is more than one diameter. NASA's fact sheet gives a volumetric mean radius of 6,371.0 km, which doubles to a mean diameter of 12,742 km (7,918 mi). Across the equator the diameter is 12,756 km (7,926 mi), the figure NASA quotes on its Earth page. Through the poles it is 12,713.5 km (7,900 mi), twice the polar radius of 6,356.752 km.^[1][2]

Why the equator is wider

Earth's equatorial radius is 6,378.137 km and its polar radius is 6,356.752 km, so the planet bulges at the equator. NASA's fact sheet lists the flattening as 0.003353; Wikipedia gives it as 1/298.257. The bulge shows in the circumference too: 40,075 km (24,901 mi) around the equator against 40,008 km (24,860 mi) around a meridian through both poles.^[2][3]

Compared with the Moon

Across the equator, 12,756 km, Earth is the fifth-largest planetary-sized body in the Solar System, according to Wikipedia. The same article describes Earth as 3.7 times larger than its Moon. NASA's Moon fact sheet puts the Moon's mean radius at 1,737.4 km, which is 0.2727 of Earth's mean radius of 6,371.0 km.^[3][4]

Did you know?

Earth bulges at the equator: it is about 43 km wider there than it is from pole to pole.

Questions people ask

Sources

1. Earth: Facts - NASA Science science.nasa.gov
2. Earth Fact Sheet - NASA NSSDC nssdc.gsfc.nasa.gov
3. Earth - Wikipedia en.wikipedia.org
4. Moon Fact Sheet - NASA NSSDC nssdc.gsfc.nasa.gov

More sizes

• Moon3,475 km · 2,159 mi across
• Saturn (with rings)280,000 km · 173,984 mi across
• Sun1,391,400 km · 864,576 mi across
• Saturn V moon rocket111 m · 364 ft tall
• International Space Station109 m · 358 ft wide
• SpaceX Falcon 9 rocket70 m · 230 ft tall

See the Sun, planets and Moon to scale

See all 184 sizes