How tall is Mount Everest?

October 1, 2020 • 1:30 pm

If you asked me the height of Mount Everest, I could tell you without missing a beat: 29,029 feet (I don’t know it by heart in meters, but it’s 8,848 m).  That’s been the accepted height since the 1954 Survey Of India, which established the height using a number of observation stations and triangulation (trigonometry). Since then, there have been a few other measurements, all yielding heights close to the 1954 data: a 1999 National Geographic measurement gave 29,035 feet (seven feet higher), while a 2005 Chinese survey yielded 29,017 (that was the rock height, neglecting the roughly ten feet of ice and snow covering the summit).

There’s no doubt that Everest’s summit is the highest spot on earth measured from sea level (Chimborazo in Ecuador, however, is the highest mountain measured from the Earth’s center), but people want an exact figure. This article in the new National Geographic (click on screenshot) shows the difficulty of actually getting that figure.

First of all, the height of Everest keeps changing, both rapidly and slowly. Slowly because it’s still rising as the Indian tectonic plate collides with the Asian one—the event that created the Himalayas to begin with. That rise is about 0.5 centimeters per year. The more rapid changes are due to earthquakes: one in 1934 is supposed to have lowered the mountain by two feet. Then there’s the decision about whether to count the ice and snow blanketing the peak in its total height, for that blanket can be up to ten feet thick. (Triangulation of course includes that.)

Finally, there’s the tough decision about the baseline, taken as “sea level.” The problem is that calculating “sea level” is hard because it varies from place to place and time to time due to irregularities in the Earth’s shape, and so what they’d like is “what the sea level would be under Mount Everest if there were sea under Mount Everest”.  That involves making two models, as depicted in the figure below from the article, and it’s apparently the sum of the geoid height and the ellipsoid height is the mountain’s height. (It’s a bit complicated, and I can’t say I understand it fully, because sometimes the geoid height looks to be negative.)

The first of two recent sets of measurements were taken by a Nepalese survey team that climbed Everest in 2019, summiting in the middle of the night to avoid the rush of climbers.  Laser trigonometry as well as GPS technology established the summit height. They also used a method to determine the thickness of ice and snow on the summit. That “official” height is now known but hasn’t been revealed, for the Chinese get a say as well: the border between China and Nepal runs right through the summit, and so this spring, when all expeditions were canceled because of the pandemic, the Chinese used a combination of climbers and a surveying plane to get their own height (see below).

And politics are involved as well:

“There’s a lot of history here,” says Ed Douglas, a respected Everest historian who recently published a history of the Himalaya. Douglas notes that, like Nepal, China has long used Everest as a symbol of national identity. In 1960, Mao Zedong ordered a large state-run expedition of Everest. That team made the first successful ascent from the Tibet side of the mountain. During the 2008 Beijing Olympics, China imposed restrictions on climbers on the Tibet side of the mountain so that an official expedition could carry the Olympic torch to the top without incident.

Nepal, one of the poorest nations in Asia, has numerous reasons to keep its wealthy and powerful neighbor happy. During the last fiscal year, some 90 percent of foreign direct investment in the nation came from China, and during his state visit, Xi pledged $500 million in financial aid. This comes in addition to the millions of dollars China has invested in Nepali infrastructure projects, including new airportsrailways, and hydropower plants.

There is precedent for Nepal and China coordinating on the issue of Everest’s height. After the Chinese completed their 2005 survey, Nepal and China announced a joint agreement to recognize both the new Chinese survey of the highest point of rock and the 1954 Survey of India elevation, which included the snowcap.

So we’ll have at least two new heights, and they’re very unlikely to be identical. But it doesn’t really matter, as Everest will remain the highest spot on Earth—calculated from an estimated sea level. That’s why I trekked in to see it twice, and why so many have tried, and many have died, trying to stand on the roof of the Earth. It’s a beautiful place to visit, and an excellent trek, and I’m content to not have climbed it. Seeing it was enough, for, believe me, you may think you’ve seen high mountains, but, like Crocodile Dundee’s knife, this is a mountain! I wish I could embed some of the photos I took on my trips, which are on 35 mm Kodachrome slides.

Here are two photos from recent measurement efforts. Photos and captions are from National Geographic:

In 1999 an American expedition put a GPS receiver on the summit of Mount Everest to calculate a new elevation. PHOTOGRAPH BY TRIMBLE

From the recent Chinese expedition:

A member of a Chinese survey team sets up a marker on the summit of Mount Everest on May 27, 2020. With the mountain closed to virtually all other climbers due to COVID-19 during the spring of 2020, China sent an expedition to remeasure the mountain, which is known to Tibetans as Qomolangma. PHOTOGRAPH BY XINHUA, ALAMY

Below is an informative but scary chart from the Encyclopedia Brittanica, showing the peril of trying to climb it. Even I got cerebral edema climbing the small peak next to it, Kala Patthar, which is only 18,519 feet (5,644 m). That, and not base camp, is where you get the view of Everest in all its glory. (You can’t see anything from base camp.)

I made it up and down Kala Patthar on both treks, but the second time I got cerebral edema, wanted to lie down and sleep (my companion stopped me from that, knowing I’d die) and I repeatedly stumbled trying descend. I stopped at the Trekker’s Aid Post nearby for a checkup, and they told me what I had and that it would go away when I descended. (A doctor inhabits a quonset hut during the trekking season.)  I hiked down to 15,000 feet, and then I was fine.

Here, from Wikipedia, is the view of Everest from Kala Patthar. On both days I climbed the small mountain, it was perfectly clear like this, and the view was stupendous. (There was also plume of snow from Everest’s summit, showing high winds.)

h/t: Andrew Berry, a fellow Everestphile

39 thoughts on “How tall is Mount Everest?

  1. Interesting article. I think it’s important to include the snow and ice and to provide a caveat of ± xx ft (m) for snow/ice. This is typical for most summits.

    The snow and ice certainly count for climbers and airplanes — about the only practical users of the data.

  2. It’d be interesting to know how the other highest mountains sort based on the different estimation methods. My wild guess is Everest is a safe distance from the next highest anything by any measure… not sure about that one in Patagonia though….

      1. Here’s the picture e I was thinking of : highest point from Earth’s “center”, which can probably have a couple definitions:

        “Chimborazo’s summit is also the farthest point on the Earth’s surface from the Earth’s center given that it is located along the planet’s equatorial bulge. Chimborazo’s summit, therefore, is at a higher point than the summit of Mount Everest which is measured from sea level. ”

        and of course we know this is precisely the point (pun!) of this post (pun 2!) – the measurement of each point (pun 3!).

        1. The hell autocorrect- I can’t even remember what I was trying to write but it wasn’t “picture e I”

    1. Chimborazo is pretty close to the Equator (Wiki gives me 1deg28′ south), which is necessary for the oblateness of the figure of the Earth to have ~2.5km of effect over Everest’s geocentric height. (Everest is at 27deg59′ north). The total difference between mean equatorial radius and mean polar radius is a smidgin over 30km – but varies with each major earthquake so there isn’t a lot of point in memorising it to better than one significant figure.)
      “Patagonia” is normally considered as pretty far south – beyond 40-odd degrees south.

      It must be nice to live in a country like Mexico with beautiful mountains like Mt Logan.

  3. When I was in Pakistan in the late 1980s, some Pakistanis were very keen to tell tourists about a new satellite measurement technique that they said had measured K2 as being higher than Everest. However, IIRC it seemed that as soon as the new measurement of Everest was made it would regain its title as the world’s tallest mountain.

    1. Yes, the methodology of the 1986 measurement was very soon shown to be flawed, and many later measurements of both mountains (starting the very next year) have re-confirmed their relative positions, i.e. that however you measure it, Everest is the best part of 800 feet higher than K2.

      1. Thanks, Jonathan – I was in the Karakorams in 1987, so that will be the measurement I was referring to.

  4. Geoid height can indeed be negative. It is usually expressed with respect to the reference ellipsoid, which approximates (an average, if you will) the geoid but is smoother. Mass excess will result in positive geoid heights, and mass deficits in negative heights.

    1. To be a smartass:

      1/ How is that base defined?

      It is said that Mont Logan in Canada is the most massive mountain on Earth, because some sort of base encompasses a huge area, above which is a lot of (pup tent shaped) mountain, the highest in Canada, but not quite as high as Denali in US.

      2/ Is there not a much higher mountain on Mars?

      Less gravity there, so a piece of pie to climb, though not without oxygen.

    2. Of course Douglas Adams argued that Mount Kilimanjaro was the tallest mountain based on a similar concept of “mountain” and ignoring mountains that are obscure by sea. For my own point I believe we have 4 tallest mountains in the world and am happy to include more if they have convincing enough claims

  5. I’ve mentioned this before, but Nirmal Purja broke his previous Guinness World Record by climbing Mount Everest, Lhotse, and Makalu all within 2 days and 30 minutes! He achieved this on his way to setting the record for the fastest ascent of all 14 mountains over 8,000 metres (6 months and 6 days) – the previous record had been almost 8 years), and he climbed the last five summits in only 12 days.

    1. Lhotse and Everest are neighbours – literally. The South Col, by which the Donkey Track gets to the summit of Everest is defined by ridges coming from Everest and Lhotse and the routes are common below camp 3.
      Some of these people are getting like fell runners. It’s going to end in tears. No, rephrase that – there will be tears and empty-coffin funerals, but it won’t stop people from racing the clock.

    1. True, but not a lot. The tonnage of snow and ice in valley glaciers is negligible compared to even a fairly small ice sheet.

  6. One of my treasured gifts from my father is an illustrated volume called ‘The Wonder Book of the Wild’. It was a Christmas present to him in 1924, when he was 8. It includes a chapter by Capt George Finch, who led the 1922 expedition to Everest, and reached an altitude of 27,300ft.

    They thought Everest was 29,002ft high. That’ll do for me.

    1. The Survey of India’s Raj era triangulation produced, after weighting, distribution of errors, etc, a height of 29000ft exactly. So they arbitrarily added a couple of feet, to make it sound “not an estimate”.
      Well, that’s been the story since I was a sprog. IT might even be true.

  7. I heard that the original height they measured was exactly 29000 feet, but that they recorded it as 29002/29029 feet so it didn’t look like an estimate.
    Is this true?

  8. An alien spacecraft which somehow can avoid completely any air resistance gets itself into a perfect circular Newtonian orbit around the centre of mass of the earth. It uses the great circle defined by a pair of points, in this case those on the lines joining the summits of two great mountains to that centre. First time round it clears one summit, of Everest, but then humanity is saved when it crashes into the other summit, of course that of Chimborazo in Ecuador.

    But it had remained on that perfect great circle. So which is the highest point on earth?

    Good old Humboldt, about half a century older than Darwin, had a great influence on the latter, and the two even communicated by letter, IIRC. With his South America companion, Humboldt held the record for the highest climb ever around 1805 (highest above sea level of course). But that was only part ways up Chimborazo; the summit was out of reach.

  9. As you say, the height is constantly changing. When (not “if”) the Himalayan Front Fault unleashes it’s 3 to 4 centuries of pent up strain (“strain” in the “delta-length/original length sense) it could drop a thousand feet of the top of Everest down the Kangshung face as a minor side-effect of having the first (probably) megadeath earthquake.
    At least, that’s the fault I’ve been putting my two-beers worth on since I started to think about where the most serious earthquake threat in the world is.

  10. I recall a question on the UK TV comedy show “QI” chaired by Stephen Fry on who first put two feet on Mt Everest.

    – The first person to put two feet on the top of Mount Everest was Bengal mathematician Radhanath Sikdar.
    He was the first person to identify Everest as the world’s highest mountain.
    He measured it to be exactly 29,000 feet. However, he thought no-one would believe him, thinking he just rounded the number off, so he added two feet to the measurement to make it look as if he was incredibly precise.
    So 29,002 feet was the official measurement, although it is now known to be 29,028 feet.

  11. According to Monty Python there is an excellent hair salon on Mt. Everest, thanks to the International Hairdressers’ Expedition:

  12. One of my favourite trick questions / bad jokes is this:
    Q/ What was the highest mountain in the world before Mt Everest was discovered?
    A/ Mt Everest

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