Everest Summit Success Rate: What the Numbers Say

The Everest summit success rate is one of the most misunderstood numbers in mountaineering. Depending on which figure you read, "your odds of standing on top" can sound like a coin flip, a near-certainty, or a long shot — and all three can be true at once, because the headline average hides huge differences between climbers who use oxygen and those who do not, between the young and the old, and between a calm weather year and a stormy one. This guide pulls together the most reliable figures from the Himalayan Database and peer-reviewed research, explains why the rate has roughly doubled in a generation, and shows what actually moves the odds for an individual climber.

If you are researching the mountain more broadly, it pairs naturally with our look at how many people die on Everest and the science of the Everest death zone above 8,000 metres.

Key takeaways

• The all-time overall success rate is about 43 percent, but modern guided seasons typically run far higher — roughly 60 to 75 percent in good years.
• A peer-reviewed study found the rate doubled from about one-third of climbers (1990–2005) to two-thirds (2006–2019).
• Climbers using supplemental oxygen are around twenty times more likely to summit than those without; only ~1.7 percent of all summits have been oxygen-free.
• Age matters above ~40: success declines by roughly 1 percent per year of age beyond that point.
• The Nepal (south) and Tibet (north) sides have very similar long-run outcomes; weather and crowding matter more than which side you choose.
• The descent is where many serious problems occur — the summit is the midpoint of summit day, not the end.

What "success rate" actually measures

Before any number means anything, you have to know what it counts. A "summit success rate" is simply the share of people who set out to climb the mountain and reached the true summit. But the denominator varies between sources: some count every individual who joined an expedition, some count only paying members and exclude hired staff, and some report per-permit figures. That is the single biggest reason published rates disagree.

The most authoritative running tally comes from the Himalayan Database, the expedition archive founded by the late journalist Elizabeth Hawley. As summarised by mountaineering analyst Alan Arnette in his 2026 edition of "Everest by the Numbers," the mountain had recorded 13,737 summits through the end of 2025, achieved across all the people who ever tried, for an overall success rate of about 43 percent. Those summits were split almost evenly between members (clients) and hired climbers, mostly Sherpas, who do the route-fixing and load-carrying.

That 43 percent is a lifetime average stretching back to the first ascent in 1953. It is not the number a modern climber should expect, because the early decades — before bottled oxygen was routine, before accurate forecasting, before fixed ropes ran the whole route — were far leaner.

How the odds doubled in a generation

The clearest evidence that Everest has changed comes from a 2020 peer-reviewed study published in PLOS ONE, led by researchers including Raymond Huey and analysed with help from the University of Washington. Comparing two eras, the authors found that the summit success rate roughly doubled: from about one-third of climbers reaching the top in 1990–2005 to about two-thirds in 2006–2019. The University of Washington summarised the finding bluntly — success rates doubled while the death rate stayed about the same.

Several things changed at once to produce that jump:

Weather forecasting

Modern expeditions buy specialised mountain forecasts that pinpoint the short, calm "summit windows" each May. Climbers can now wait out storms and move only when the jet stream lifts off the summit, instead of gambling on a fixed date.

Equipment and oxygen systems

Lighter down suits, better boots, and more reliable oxygen regulators mean climbers arrive at the high camps less worn down and breathe more efficiently up high.

Sherpa support and fixed ropes

Sherpa teams fix continuous rope from the lower mountain to the summit, break trail, stock the camps and carry the oxygen. This infrastructure is the quiet engine behind the modern success rate — it opened the mountain to climbers who could never have route-found it alone.

The same study added an important caveat: while more people succeed, the value of personal experience has shrunk. The boost that climbing experience gave to your odds in 2018 was only about half what it was 25 years earlier — because the support system now does much of what experience used to.

The single biggest factor: supplemental oxygen

If you want to predict whether a climber reaches the top, the most useful question is not how fit they are. It is whether they are breathing bottled oxygen.

The Himalayan Database figures are stark. As Arnette's analysis notes, members using oxygen were about twenty times more likely to summit than those who climbed without it. And across the entire history of the mountain, only 232 climbers — about 1.7 percent of all summiters — reached the top without supplemental oxygen.

| Oxygen use | Approximate share of summits | Relative chance of success | |---|---|---| | With supplemental oxygen | ~98% | Baseline (much higher) | | Without supplemental oxygen | ~1.7–2% | Roughly 20× lower for members |

The physiology behind this is covered in our death zone article: above 8,000 metres the air holds only about a third of the oxygen available at sea level, and bottled gas effectively "lowers" the mountain by a few thousand metres for the body. It does not just improve comfort — it changes whether the climb is survivable for most people.

Age, sex and experience

The 2020 PLOS ONE study is also the best source on who succeeds. Its findings, drawn from thousands of climbers, are nuanced:

• Age: Success is roughly flat until about age 40, then declines steadily — by about 1 percent for each additional year. The authors note a present-day 60-year-old has about the same success chance (~40 percent in their model) as a 40-year-old did in the earlier era.
• Sex: Probabilities of summiting — and of dying — were broadly similar for men and women. Everest does not appear to favour one sex at the summit.
• Experience: Prior high-altitude experience, especially in Nepal, raised the odds of success. A genuine first attempt with no eight-thousand-metre background is measurably harder.

The practical message for an aspiring climber is that fitness is necessary but not sufficient. Time spent acclimatising and learning to function at altitude — the same skills our altitude sickness guide describes for trekkers — does more for your odds than raw cardio alone.

South side vs north side

Climbers often ask whether Nepal's south side (via the Khumbu and Everest Base Camp) or Tibet's north side is "easier." The long-run statistics say the difference is small.

| Side | Approx. summits (through 2025) | Approx. fatality rate | |---|---|---| | Nepal (south) | ~9,887 | ~2.3% | | Tibet (north) | ~3,850 | ~2.8% |

Both sides cluster around one death per hundred summits and a fatality rate a little over two percent, per Arnette's compilation of the database. What actually drives a given year's success is the weather window and crowding — a long, stable window lets more teams summit safely, while a single short window forces everyone into the same days and raises queueing risk. Neither side offers a reliable shortcut.

Why the summit is the midpoint, not the finish

A high success rate can create a dangerous illusion that reaching the top is the goal. Experienced guides are emphatic that the summit is the halfway point of summit day. Climbers turn around already exhausted, dehydrated and oxygen-starved, and a large share of the mountain's most serious incidents happen on the way down. This is why turnaround times exist: a strict cut-off hour after which you descend whether or not you have topped out.

Our companion piece on how many people die on Everest goes deeper into where and why fatalities occur, but the headline is simple — a successful climb is one where you get back to camp, not just one where you reach the top.

Recent seasons in context

Year-to-year numbers swing with the weather. Reporting on the 2024 season indicated a success rate near 76 percent for foreign climbers on the south side, a notably high figure attributed to good windows. The 2025 season saw hundreds of summits across both sides, with the north (Tibet) side growing in popularity. These strong recent years sit well above the all-time 43 percent average — a reminder that the lifetime figure and the "what should I expect this year" figure are simply different questions.

If your own Everest ambitions start with the walk-in rather than the summit, our guides to the Everest Base Camp trek itinerary and whether you need a guide are the better starting points.

The bottom line

For a well-supported, oxygen-using climber in a normal weather year, reaching the summit of Everest is now more likely than not — a genuine shift from the long-shot odds of the early expedition era. But "more likely than not" is an average. The numbers make clear that bottled oxygen, age, prior altitude experience, the weather window and the discipline to turn around all move an individual's real chances far more than the headline percentage suggests. Read the average as a starting point, not a promise.

Sources

• Alan Arnette — Everest by the Numbers: 2026 Edition: https://www.alanarnette.com/blog/2026/01/26/everest-by-the-numbers-2026-edition/
• Huey et al. (2020), "Mountaineers on Mount Everest: Effects of age, sex, experience, and crowding on rates of success and death," PLOS ONE / PMC: https://pmc.ncbi.nlm.nih.gov/articles/PMC7449495/
• University of Washington News — "Mount Everest summit success rates double, death rate stays the same over last 30 years": https://www.washington.edu/news/2020/08/26/mount-everest-summit-success-rates-double-death-rate-stays-the-same-over-last-30-years/
• The Himalayan Database (Elizabeth Hawley expedition archive): https://www.himalayandatabase.com/seasonlists.html
• ExplorersWeb — Everest and Other 8,000ers by the Numbers: https://explorersweb.com/everest-by-the-numbers/