Mount Everest is the highest point on Earth above mean sea level. That statement is true, but it is not the same as saying Everest is the tallest mountain on Earth.

The difference comes from where the measuring starts. Everest rises to 8,848.86 meters above mean sea level, the reference surface used for most elevations. Mauna Kea, the large shield volcano on the Island of Hawaii, reaches only 4,207 meters above sea level. On a normal map, Everest wins easily.

Measured from base to peak, the ranking changes. The National Oceanic and Atmospheric Administration says Mauna Kea rises more than 10,210 meters, or 33,500 feet, from its base deep beneath the Pacific Ocean to its summit. Most of that mountain is underwater.

The result is a useful reminder that “highest” and “tallest” are not always the same measurement.

Everest wins by altitude

When people call Everest the world’s highest mountain, they are usually talking about elevation above mean sea level. That is a practical convention because sea level gives surveyors a shared reference surface, even though the real ocean is uneven and Earth itself is not a perfect sphere.

By that standard, Everest is still first. The mountain sits in the Himalaya on the border of Nepal and China, and its currently accepted official height is 8,848.86 meters. That number comes from a 2020 joint announcement by Nepal and China, after both countries had worked to reconcile earlier measurements.

Sea-level elevation is the number that matters for aviation, mapping, altitude sickness, climbing records, and most ordinary descriptions of terrain. A climber standing on Everest is standing higher above the ocean’s average surface than a climber standing anywhere else on land.

That does not mean Everest has the largest vertical body.

Mauna Kea wins by base-to-peak height

Mauna Kea is a shield volcano. The U.S. Geological Survey lists its summit elevation at 4,207 meters and describes it as a basaltic shield volcano on the Island of Hawaii. Above the ocean, it is less than half Everest’s height.

Below the ocean, the scale changes.

The Hawaiian Islands are the exposed summits of volcanoes built from the seafloor by repeated eruptions. Mauna Kea began on the Pacific seafloor, accumulated lava over a long period, and now stands as a broad volcanic edifice whose lower slopes are hidden by water. If the measurement starts at the submarine base rather than sea level, NOAA’s figure of more than 10,210 meters makes it taller from base to summit than Everest is from sea level to summit.

This does not make one measurement more real than the other. It means the answer depends on the question.

Base is harder to define than sea level

Sea level is not simple, but it is at least a formal reference surface. The base of a mountain is less tidy. Mountains do not usually begin at a neat line. They grade into surrounding terrain, overlap with neighboring slopes, or sit on broad foundations that can be defined more than one way.

That is why base-to-peak height can be more debatable than elevation above sea level. Everest’s summit height can be surveyed against a vertical datum. Mauna Kea’s full height depends on deciding where the volcanic pile begins on the ocean floor.

For Mauna Kea, the broad claim is still well supported: the mountain’s underwater portion is large enough that the whole volcano, measured from its submarine base, is taller than Everest. The exact number can vary by definition, but the order does not change under the usual NOAA-style base-to-peak comparison.

There is a third way to measure height

There is another wrinkle. If the question is which summit is farthest from Earth’s center, neither Everest nor Mauna Kea is the answer. NOAA points instead to Mount Chimborazo in Ecuador.

Chimborazo is only 6,268 meters above sea level, far lower than Everest by altitude. But Earth bulges at the equator because of its rotation. Chimborazo sits close to that bulge, which places its summit more than 2,000 meters farther from Earth’s center than Everest’s summit.

That gives three different winners: Everest by elevation above sea level, Mauna Kea by base-to-peak height, and Chimborazo by distance from Earth’s center.

None of these answers is a trick. They are different definitions applied to a planet that is round, rotating, ocean-covered, and geologically uneven.

The measurement changes the story

The Everest and Mauna Kea comparison matters because it shows how much of Earth’s topography is hidden by water. On land, mountains are visible from base to summit only when their bases sit above sea level. Oceanic volcanoes do not have that advantage. Much of their structure is submerged, even when the summit becomes an island.

Mauna Kea’s visible peak is therefore only the upper part of a much larger volcanic mountain. Looking only at the part above sea level is useful for one kind of measurement, but it leaves out most of the mountain’s physical structure.

Everest remains the highest place a person can stand above mean sea level. Mauna Kea remains the taller mountain when the measurement begins at the base of the mountain itself.

The correction is not that Everest is less impressive. It is that Earth’s largest forms often depend on where the ruler starts.

Correction, September 20, 2026: The headline was revised to remove the false claim that Mauna Kea is nearly twice Everest’s height.