Which Mountain Is Really the Tallest in the World?

Ask ten people what the tallest mountain in the world is. Nine will say Mount Everest. Spoiler: that only holds if you measure from sea level. Measure from the base of the mountain and Mauna Kea in Hawaii is more than 1,300 meters taller. Measure from the center of the Earth and Chimborazo in Ecuador reaches farther into space than any other point on the planet. Three mountains, three answers. We show you why Everest only owns one of three height records.

The simple answer: Mount Everest

Mount Everest is 8,848.86 meters (29,031.7 feet) tall. That is its height above sea level, officially confirmed in 2020 by a joint survey from Nepal and China. That is why every textbook says Everest is the tallest mountain in the world.

Everest sits in the Himalayas on the border between Nepal and China. It is part of the mountain range that formed when the Indian continental plate slammed into the Eurasian plate about 50 million years ago. And it is still growing, roughly four millimeters per year, because the plates keep pressing against each other.

But height above sea level is just one way to measure a mountain. And that is where things get interesting.

Why isn't that the whole story?

When you measure a mountain you can do three things: take the height above sea level, measure from the base, or measure the distance from the center of the Earth. Each method gives a different answer. Not by a few meters, but by thousands.

The sea-level method is the standard answer. But it is arbitrary. If the base of a mountain sits deep underwater, that part just gets ignored. And it doesn't account for the fact that Earth isn't a perfect sphere. The planet bulges at the equator by roughly 21 kilometers (13 miles) compared to the poles.

Did you know?

Measured from its base on the ocean floor, Mauna Kea stands roughly 10,200 meters (33,500 feet) tall. That is over 1,300 meters more than Mount Everest. Most of the mountain is simply hiding underwater.

Mauna Kea: the tallest when you measure from the base

Mauna Kea is a dormant volcano in Hawaii. From the highway it looks unremarkable: a round summit, 4,207 meters (13,803 feet) high. Less than half of Everest. But Mauna Kea doesn't start at sea level. It starts about 6,000 meters below it, on the floor of the Pacific Ocean.

From base to peak, Mauna Kea is about 10,200 meters (33,500 feet) tall. That is the true size of the mountain if you count the whole thing. For context: the deepest point in the ocean, the Mariana Trench, is about 10,935 meters deep. Mauna Kea is almost as tall as the Mariana Trench is deep.

On top of Mauna Kea, you will find some of the world's most important astronomical observatories. The air is thin, dry, and dark. For astronomy, the conditions are close to perfect.

Chimborazo: the closest point to outer space

Chimborazo is a volcano in Ecuador. Its height above sea level is 6,263 meters (20,548 feet). Less impressive than Everest at first glance. But here is the twist: Earth isn't a perfect sphere. Because the planet spins, it bulges at the equator, which means the equator is farther from Earth's center than the poles.

Chimborazo sits just about one degree south of the equator. Its summit is therefore roughly 6,384.4 kilometers from the center of the Earth. Everest's summit, by comparison, is only about 6,382.3 kilometers out. The difference is roughly 2,100 meters (about 6,900 feet).

So if you are looking for the point on Earth's surface that is farthest from the center of the Earth and therefore closest to outer space, it is not Everest. It is the summit of Chimborazo in Ecuador.

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How the three mountains stack up

Here is a quick overview of which mountain holds which record:

Mount Everest: 8,848.86 m above sea level, the tallest summit using the standard measurement.
Mauna Kea: roughly 10,200 m from base to peak, the tallest mountain if you count the whole thing.
Chimborazo: roughly 6,384.4 km from Earth's center, the farthest point from Earth's center even though its summit is only 6,263 m above sea level.

Three mountains. Three different records. All three are legitimate answers to “Which mountain is the tallest?”

Which mountain is really the tallest in the world?▾

It depends on how you measure. From sea level, it is Mount Everest at 8,848.86 meters. From its base, it is Mauna Kea in Hawaii at roughly 10,200 meters. From the center of the Earth, it is Chimborazo in Ecuador.

How tall is Mauna Kea from the ocean floor?▾

About 10,200 meters (33,500 feet). The mountain starts around 6,000 meters below sea level and rises another 4,207 meters above it. That makes it the tallest mountain in the world when measured from base to peak.

Why is Chimborazo farther from Earth's center than Everest?▾

Earth isn't a perfect sphere. Because the planet spins, it bulges at the equator and flattens at the poles. Chimborazo sits near the equator while Everest is much farther north. That puts Chimborazo's summit about 2,100 meters farther from the center of the Earth.

Is Mount Everest still growing?▾

Yes. The Indian continental plate keeps pushing into the Eurasian plate, which shoves Everest up by about four millimeters per year. Erosion chips away at it at the same time, but on balance the mountain is still gaining height.

How big is the difference between Mauna Kea and Everest from the base?▾

Mauna Kea is roughly 10,200 meters from the ocean floor. Everest is 8,848.86 meters from sea level, but its base sits on a plateau that is already about 5,200 meters high. Everest itself is therefore only about 3,600 meters from its base to its peak.

What's the deepest point on Earth?▾

The Mariana Trench in the Pacific. Its lowest point, the Challenger Deep, is about 10,935 meters (35,876 feet) below sea level. That is more than Mount Everest is tall. If you dropped Everest into the Mariana Trench, its summit would still be more than 2 kilometers underwater.

Which mountain is the hardest to climb?▾

Technically, K2 in the Karakoram range is the toughest of the eight-thousanders. At 8,611 meters it is the second tallest mountain in the world, but it has much steeper flanks and worse weather than Everest. Far fewer people have summited K2 than Everest.

So which mountain is the tallest? Everest, Mauna Kea, or Chimborazo, all three are right depending on how you measure. Next time this question comes up in a quiz, remember the three methods. If you want more geography twists like this, check out How big is Greenland really? and The tallest structures in human history. Or jump straight into our geography quiz.