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Earth’s Radius: Equatorial, Polar, Diameter, Circumference, Shape (2023)

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How many kilometers is the EarthCurious about the size of our planet? Earth is the biggest of all terrestrial planets and fifth largest in general, with a radius measuring 3,959 miles (6,371 kilometers).

In this article we’ll explore Earth’s equatorial and polar radii as well as its diameter, circumference and shape.

Additionally, you’ll learn how these measurements compare to other planets in our solar system.

With an increased understanding of Earth’s size comes an appreciation for its unique geographical features that make it so suitable for sustaining life, which unfortunately are changing due to climate change.

Get ready to discover just how many kilometers make up the earth’s radius!

Key Takeaways

  • Earth’s radius is approximately 6,371 kilometers.
  • The equatorial radius of Earth is 6,378.1 kilometers, while the polar radius is 6,356.8 kilometers.
  • The difference between the polar and equatorial radii is 21.3 kilometers.
  • The radius of Earth is a crucial measurement in understanding its size and shape.

Earth’s Radius

You likely know that Earth’s shape is not a perfect sphere, but rather an oblate spheroid, with a noticeable difference between the equatorial and polar radii. Specifically, Earth’s mean equatorial radius is approximately 6,378.1 km (3,963.

2 miles), while its polar radius is about 6,356.8 km (3,949.9 miles), making the equatorial radius around 21 kilometers larger than the polar radius.

Equatorial Radius

You’ve read that Earth’s equatorial radius measures around 6,378 kilometers long. This key geographical measurement defines one dimension of Earth’s oblate spheroid shape. Compared to measurements at the poles, the equatorial radius indicates the bulge circling our planet’s midsection.

Understanding dimensions like the equatorial radius has developed from ancient beliefs in a spherical Earth to modern satellite confirmation of its slightly flattened form. With knowledge of Earth’s precise equatorial radius, we gain perspective on our terrestrial planet’s true shape and place in space.

Polar Radius

Although some believe Earth’s polar radius could differ substantially from its equatorial radius, careful measurements have shown the difference amounts to a mere 22 kilometers.

  1. The polar radius is 6,356.8 km.
  2. The equatorial radius is 6,378.1 km.
  3. Their difference is 21.3 km.

Despite Earth’s oblate spheroidal shape, its polar and equatorial radii are quite similar. This reflects the stability provided by Earth’s axial tilt, which keeps variations in the polar radius small over long timescales.

Precise measurements help us better understand our planet’s geometry and interior structure.

Earth’s Diameter

You should know that Earth’s equatorial diameter measures about 12,756 km (7,926 miles), while the polar diameter is around 12,713.6 km (7,899.86 miles). These values describe Earth’s oblate spheroidal shape, with a slightly larger diameter along the equatorial bulge compared to the distance measured from pole to pole.

Equatorial Diameter

There are an astounding 43 kilometers more around Earth’s lush middle. The equatorial diameter measures 12,756 kilometers due to our home’s pear-shape. Geodetic measurements precisely establish the length of planetary circumferences.

Earth’s vital statistics derive from space-age data. Comparisons establish Earth’s claim to the grandest terrain in the inner solar system. Careful calculations confirm the equator’s slight bulge. Numbers delineate the contours of spheres in space.

Precision quantifies the nuances of planetary size. Subtle study reveals subtle truths.

Polar Diameter

Look here – Earth’s polar diameter is only 64 miles shorter than its equatorial one. Our planet’s shape has minor variations from being a perfect sphere. Its polar circumference measures 24,860 miles. The poles don’t bulge out quite as much as the equator. This oblate spheroid still appears round but has geographical differences between the polar and equatorial diameters.

While almost identical in length, the 64 mile contrast highlights Earth’s non-uniform shape. The polar diameter is slightly shorter than the equatorial diameter, reflecting the fact that the planet bulges slightly at the equator.

Earth’s Circumference

You live on a planet with precise dimensions that have been calculated over thousands of years. The circumference around Earth’s equator is about 40,075 kilometers (24,901 miles), while the circumference from pole to pole is approximately 40,008 kilometers (24,860 miles).

Equatorial Circumference

You could measure our planet’s 40,075 km waistline firsthand if you raced nonstop along the equator. Earth’s equatorial circumference results from a slight bulge around its middle. Modern geodetic measurements precisely quantify our home planet’s parameters.

Throughout history, thinkers analyzed Earth’s round shape and calculated its circumference with limited accuracy. Equatorial diameter exceeds distance between poles by 43 km due to centrifugal forces from Earth’s rotation.

Comprehending latitude correlations and global circumference progressed immensely in the Space Age.

Meridional Circumference

You’ll find the meridional circumference measures about 40,008 kilometers from pole to pole. This distance from the North Pole to the South Pole represents Earth’s longest dimension. Modern satellite geodesy provides precise measurements. Earth bulges at the equator due to centrifugal forces from rotation.

This results in different equatorial and meridional values. Interior density variations like the liquid outer core also cause Earth’s geoid shape to deviate slightly from a perfect oblate spheroid. Accurate knowledge of our planet’s size and shape relies on advanced geophysical techniques.

Earth’s Shape

Hello, let’s discuss the shape of the Earth. The Earth’s shape is an oblate spheroid with an equatorial bulge due to its rotation. Even though the Earth is mostly spherical, there are slight variations between the equatorial and polar diameters, making the equator approximately 43 kilometers larger than the pole-to-pole measurement.

Oblate Spheroid

Though the Earth resembles a sphere, gravity’s force made her waist bulge up to 43 kilometers bigger around the middle. She spins fast, so centrifugal force pushes matter outward. This stretches the equator into an ovalish, squashed shape called an oblate spheroid.

Ancient thinkers supposed a perfect sphere. But modern satellite data confirms the bulge. Like a peach, the planet’s shape has flattened poles and expanded equator. Her figure shows that gravitational and centrifugal forces sculpt planetary shapes.

Equatorial Bulge

There’s a slight bulge around the equator from the Earth’s rotation. The Earth’s rotation causes centrifugal force effects, creating a bulging effect at the equator. Gravity is slightly weaker at the equator compared to the poles, making the equatorial radius 43 kilometers larger than the polar radius.

Geodetic models like the World Geodetic System precisely define Earth’s complex shape, accounting for the equatorial bulge and other slight deviations from a perfect sphere. This non-uniformity has tectonic implications, as evidenced by phenomena like plate tectonics and mantle convection currents.

The equatorial bulge is a key factor in representing Earth’s oblate spheroidal shape.

Earth’s Size and Comparison

Let’s talk about Earth’s size and comparison to other planets. With a mean radius of approximately 6,371 kilometers, Earth is the largest of the terrestrial planets, bigger than Venus and Mars. However, Earth’s size is dwarfed by the gas giants like Jupiter and Saturn, and its surface displays extremes from the peak of Mount Everest to the depths of the Mariana Trench.

The blue planet’s diameter at its equator is 7,926 miles (12,753 km). Though it is not perfectly round due to its rotation, our home planet is very close to a perfect sphere. When compared to the enormity of Jupiter and Saturn, the third rock from the sun barely seems to register on the scale.

However, among the terrestrial bodies within the inner solar system, Earth looms large above its nearest neighbors.

Comparison With Other Planets

You feel small standing on Earth, a marble in the solar system, compared to gas giants like Jupiter.

  • Earth has the largest radius of any terrestrial planet at 6,371 km.
  • Venus is 95% of Earth’s size, while Mars is only half as large.
  • Among the rocky inner planets, Earth stands out as the largest.

Though dwarf planets like Pluto are even tinier, Earth seems tiny next to the gas giants. Its middle position in the solar system belies its relatively small size on a cosmic scale.

Notable Geographical Features

Mount Everest will take your breath away. At 8,849 meters, it’s Earth’s highest point. Many dream of reaching the summit. In contrast, Challenger Deep in the Mariana Trench plunges nearly 11 kilometers below sea level.

Our blue planet has extremes. Its radius of 6,371 kilometers encompasses everything from the deepest trench to the tallest peak.


Earth’s equatorial radius is 6,378.1 km (3,963.2 miles). Its polar radius is 6,356.

Eratosthenes was the first to calculate Earth’s approximate circumference. Today, modern technology has confirmed its shape precisely.

Earth’s diameter, circumference, and oblate spheroid shape are equally remarkable.

Our home planet’s size and shape have unique, remarkable features. Answering how many kilometers Earth’s radius is reveals one precise measurement.

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Mutasim Sweileh

Mutasim is an author and software engineer from the United States, I and a group of experts made this blog with the aim of answering all the unanswered questions to help as many people as possible.