In a Nutshell

“Tallest” and “highest” sound like the same word, but for mountains they measure two very different things. Mount Everest is the highest point above sea level, yet the tallest mountain measured from its base to its summit is Mauna Kea in Hawaii. And if you measure from the center of the Earth instead, a third mountain wins the title—Chimborazo in Ecuador.

The Whole Bushel

Ask someone to name the highest mountain on Earth and most will say Mount Everest, and they are completely right. Ask for the tallest and most will say Everest again, not realizing they have just been asked a different question. Measuring mountains is fussier than it sounds. There is still real debate over exactly how to measure one and what even counts as a mountain, and slope, elevation, volume, and steepness all come into it. But the misconception people trip over most is about height itself.

Everest is the highest because “highest” means the distance from mean sea level up to the summit, and its peak reaches 29,032 feet (8,848.86 meters), the figure China and Nepal jointly confirmed when they remeasured it in 2020. “Tallest,” on the other hand, means the full distance from a mountain’s base to its top. By that rule the winner is Mauna Kea. Most of it is hidden underwater, sitting on the ocean floor, and from base to tip it runs about 33,465 feet (roughly 10,200 meters). Everest, tall as it is above sea level, comes up shorter by more than 4,000 feet.

Drop sea level out of the picture and stand the two side by side, and Mauna Kea would be the taller mountain. It only loses the argument because so much of it is drowned and out of sight. This is also why you will hear people insist Mount Kilimanjaro beats Everest, since Kilimanjaro rises almost straight off the flat African plain while Everest is already perched high on the Himalayan plateau.

There is even a third way to crown a champion. If you measure from the center of the Earth rather than from sea level, the winner is neither Everest nor Mauna Kea—it is Chimborazo, a volcano in Ecuador. The planet is not a perfect sphere; it bulges at the equator, so ground near the equator sits farther out from the core than ground near the poles. Chimborazo stands just one degree south of the equator, which puts its summit about 6,384 kilometers from the center of the Earth, roughly two kilometers farther out than the top of Everest. By that yardstick Chimborazo’s peak is the spot on the planet closest to outer space, even though it climbs only about 20,548 feet above sea level.

Show Me The Proof

World’s Highest Mountains – World’s Tallest Mountain – and World’s Largest Mountain
Geology.com: Mount Everest has some rivals!
LiveScience: World’s Highest Mountain Summits
Guinness World Records: Tallest mountain (Mauna Kea)