How heavy is Mount Everest?

Nobody can put a mountain on a scale, so every weight for Everest is volume times rock density. The figure quoted most often goes back to Outside magazine’s The Wild File column of January 2003, which answered a reader’s question. Geophysicist Roger Bilham of the University of Colorado pointed out the catch: does Everest start at Base Camp, at 17,500 ft, or 25 miles down in the Earth’s crust? The column chose Base Camp.

It then treated Everest as a cone with an average base radius of 2.5 miles (13,200 ft), giving a base area of about 547 million square feet. A cone’s volume is a third of the base area times the height, so with 11,500 ft from Base Camp to the summit that is about 2.1 trillion cubic feet. At 170 lb per cubic foot for granite and gneiss, Everest comes to 357 trillion lb, or about 162 trillion kg. Snow and ice were left out.

The same sum in metric, with the official 2020 height: South Base Camp sits at 5,364 m, so the summit is 3,485 m above it. A cone 4.02 km in radius and 3,485 m tall holds π × 4,023² × 3,485 ÷ 3 ≈ 59 cubic kilometres. At 2,700 kg per cubic metre (2.7 g/cm³), that is about 159 trillion kg, which we round to 160 trillion kg (160 billion tonnes). The tip of that cone above 8,000 m, about 2 km across, weighs only about 2.3 trillion kg.

The answer depends far more on where you put the bottom of the mountain than on the rock. If a cone keeps the same slopes, its volume grows with the cube of its height. The Base Camp cone has sides of about 41°. Start the same cone at 4,000 m and it is 4,849 m tall, 11.2 km across and holds about 159 cubic kilometres, so the weight jumps to about 430 trillion kg. Start it at 2,800 m and it reaches about 834 trillion kg. Published figures above 800 trillion kg need a base about that low.

None of these is wrong; they answer different questions. Everest does not rise from sea level but from a range of other high peaks, and below Base Camp its rock merges with neighbours such as Lhotse and Nuptse. Bilham’s other option, counting everything down into the crust, would give a number far bigger still.

The rock itself matters much less. The summit is Ordovician limestone down to the Yellow Band at about 8,600 m, and below 7,000 m the mountain is schist and gneiss cut by sheets of granite. These rocks all weigh roughly 2.6 to 2.9 g/cm³, so choosing a different density moves the answer by a few percent, while moving the base changes it several times over.

In December 2020, Nepal and China jointly announced Everest’s official height as 8,848.86 m (29,031.69 ft), a figure that includes the snow and ice on the summit.

Everest is also still rising, by about 2 mm a year. A 2024 study in Nature Geoscience found that part of this comes from the Arun river, about 75 km away, which has carved out a huge gorge. Removing that rock lightens the crust, which floats a little higher on the mantle, and the study estimates this has added 15 to 50 m to Everest’s height over the past 89,000 years.