EBC Altitude Profile: Where Trekkers Struggle and Why

Last updated 4 October 2026. The heights, walking times and distances come from our live 12-day Everest Base Camp itinerary, which I read on 4 October 2026. The medical statements come from the sources named under each heading, and I say plainly where I could not read a source in full. This page is general information, not medical advice. Please see a doctor before you go.

The short answer: on our 12-day Everest Base Camp trek the risk is not spread evenly. By the numbers, it sits in three places. The first is the night in Namche, which is the biggest single jump in sleeping height (830 metres). The second is the stretch from Dingboche (4,410 m) to Lobuche (4,940 m) and Gorak Shep (5,164 m), where the sleeping height passes 4,900 metres and a case series of 56 pulmonary-oedema patients treated at Pheriche put the median onset at 4,834 metres. The third is the 3 am start on Day 9, which is hard but is followed by a long drop to thicker air. This guide gives you the whole profile night by night, what the published guidance says about how fast to climb, where trekkers are reported to struggle, what our guides check every day, and when we stop, rest or go down. If you want the day-by-day story of the walk itself, read our Everest Base Camp itinerary. This page is about the heights and the risk.

What does the altitude profile of our 12-day trek look like?

Altitude illness is driven mostly by where you sleep and how quickly that height rises, so the table below shows the sleeping height first, then the highest point you reach that day. Heights are from our package itinerary. Lukla is 2,860 metres, and the Kathmandu figure is 1,350 metres on our package page (the day-12 text says 1,400, see the last section). Walking times are our guides' estimates for a fit trekker.

Night	Sleep at	Sleeping height (m)	Change from the night before (m)	Highest point that day (m)	Walking time
1	Phakding	2,610	Lower than Lukla (2,860)	2,860 (Lukla)	3 hours
2	Namche Bazaar	3,440	+830	3,440	6 to 7 hours
3	Namche Bazaar (rest day)	3,440	0	3,880 (Everest View Hotel)	2 to 3 hours
4	Tengboche	3,860	+420	3,860	5 to 6 hours
5	Dingboche	4,410	+550	4,410	5 to 6 hours
6	Dingboche (rest day)	4,410	0	about 5,000 (ridge toward Nangkartshang)	about 2 hours up, then back down
7	Lobuche	4,940	+530	4,940	5 to 6 hours
8	Gorak Shep	5,164	+224	5,364 (Base Camp)	7 to 8 hours
9	Pangboche	3,985	-1,179	5,545 (Kala Patthar)	7 to 8 hours
10	Namche Bazaar	3,440	-545	3,985	6 to 7 hours
11	Lukla	2,860	-580	3,440	5 to 6 hours
12	Kathmandu	about 1,350 to 1,400	flight	2,860	40 minute flight

A few things stand out when you count rather than read. You sleep above 3,000 metres on nine nights, above 4,000 metres on four (Dingboche twice, Lobuche, Gorak Shep), above 4,900 metres on two and above 5,000 metres on one, at Gorak Shep. The flight from Kathmandu puts you at 2,860 metres in about 40 minutes, a gain of roughly 1,500 metres before you take a step, but you sleep lower, at 2,610. The climb-high-sleep-low days are real: the Day 3 hike is 440 metres above your bed, the Day 6 hike about 590 metres above it, and Base Camp is 200 metres above Gorak Shep. And Day 9 is the longest drop of the trek, 1,560 metres from Kala Patthar down to Pangboche in one day.

How fast is too fast? What the guidelines say about rate of ascent

Two sources I could read in full agree on the key number. The CDC Yellow Book chapter on high-altitude travel (last updated 23 April 2025) says: "Once above 3,000 m (9,850 ft), move sleeping altitude by no more than 500 m (1,600 ft) per day and plan an extra day of acclimatization for every additional 1,000 m (3,300 ft) of sleeping altitude gain." A 2026 practice article in the BMJ on preventing altitude illness (Adhikari, Zimmer, Brugger, Bajracharya and Basnyat) says the suggested safe ascent rate in the Wilderness Medical Society and UIAA guidelines is 300 to 500 metres a day, counted from sleeping height above 3,000 metres, with an extra night at the same height after every 1,000 metres gained. The BMJ authors say their advice rests on the 2024 Wilderness Medical Society guidelines. I could only read the abstract of the 2019 Wilderness Medical Society guidelines, so I do not quote them directly.

Now our plan against that rule. This is my own arithmetic from the table, not a published finding.

Night	Sleeping gain (m)	Against 500 m a day
2, Namche	+830	330 over, and it is the first night above 3,000 m
4, Tengboche	+420	Inside
5, Dingboche	+550	50 over
7, Lobuche	+530	30 over
8, Gorak Shep	+224	Inside

From Namche (3,440 m) to Gorak Shep (5,164 m) your sleeping height rises 1,724 metres. The rule asks for roughly one extra day for each 1,000 metres, and we put in two: the rest days at Namche and Dingboche. So the plan respects the spirit of the rule through its rest days, but three single nights are over 500 metres, one of them clearly. I would rather you read that here than discover it. The rule counts from 3,000 metres, so the Namche figure is arguable, because the climb starts below that line. I count it anyway, because your body feels the step from the previous bed.

The BMJ article also has a risk list for doctors advising travellers. A plan that climbs more than 500 metres a day above 3,000 metres, but has an extra day after every 1,000 metres of gain, sits in its moderate-risk row. A plan with no extra days sits in its high-risk row. Our plan has the extra days, so by that list it is the first kind. That list also counts your own history, for example earlier moderate or severe AMS, so it is a conversation for your doctor, not a label I can give you. If you want a spare night, tell me before you book, because it changes the schedule and the cost.

Where do trekkers actually struggle on the Everest Base Camp trek?

I do not have a counted figure for how many of our own trekkers get symptoms or turn back that I could publish and defend, so I will not give you a percentage as if I did. What I can show you is what published studies on the Everest trek found, and what our guides see day to day. Treat the numbers as a range, not a forecast. They count different people in different ways.

Source	Who	What it found	Caution
Haunolder and colleagues, International Journal of Environmental Research and Public Health, 2022 (a study of trekkers' cardiovascular risk and health conditions)	350 trekkers on the Everest Trek, mostly recruited at Tengboche (3,860 m)	25% had manifest acute mountain sickness (AMS) and 72% had at least one symptom	A snapshot at one lodge stop, on the way up
Cerfontaine and colleagues, same journal, 2022 (a study of first-aid knowledge and risk management)	366 trekkers on the Everest Base Camp Trek, by questionnaire	40.5% had at least one medical incident, and almost half of those were AMS. The abstract reports more AMS in commercially organised groups than in individually planned ones (55% against 40%)	The abstract does not explain the difference, so I draw no conclusion from it
Jones and colleagues, Wilderness and Environmental Medicine, 2013	56 patients with high altitude pulmonary oedema (HAPE) at the Himalayan Rescue Association post at Pheriche, spring and autumn 2010	Symptoms began above the aid post in 91%, at a median altitude of 4,834 m. 93% went down after treatment	Only people who reached the post. It says nothing about how many trekkers are affected overall
Cobb and colleagues, Physiological Reports, 2021	332 research volunteers on a fixed ascent to 5,300 m	73.5% scored as AMS on the Lake Louise score (23.2% mild, 50.3% moderate or severe)	A research group, scored daily. The abstract does not give their route, so it is not a forecast for a guided trek

Read together, they say two things I would stand behind. Many trekkers have some symptoms by the time they reach Tengboche, and the serious illness the Pheriche doctors treated began, in most cases, above the aid post and at a median of 4,834 metres. Our own itinerary puts the Thukla pass at about 4,800 metres and Lobuche at 4,940, so that is the stretch of our route it points at. That is my reading, not a finding of the paper. The CDC Yellow Book adds that HAPE affects "≤1 per 100 travelers at >4,300 m", and that AMS symptom onset "is usually 2-12 hours after initial arrival at a high altitude". That timing is why the evening at a new height is when the guide asks the most questions.

Here is where I see it bite on the trail, with the source for each. The first group is from our itinerary text, the second is my own judgement from the trek.

• Night 2, Namche (3,440 m). The biggest sleeping gain, plus a sustained climb of about 600 metres in one go. Our itinerary text warns that the body that feels strong at 2,600 metres will feel every step above 3,000, and the rest day follows for that reason. My judgement: it is the day people first feel the effort, usually from walking too fast.
• Night 5, Dingboche (4,410 m). Our day text says appetite changes and a dull headache arrives in the late afternoon. This is the first night above 4,000 metres, and the 550 metre step is over the guideline.
• Day 6, the Dingboche rest day. The hike to about 5,000 metres is where our itinerary has your guide clip an oximeter to your finger at the top. The point of the day is to go up and sleep back down, so do not skip the hike because you feel fine.
• Night 7, Lobuche (4,940 m). The climb to Thukla pass is the steepest sustained climb of the day, about 300 metres in roughly 90 minutes, and your guide watches your pace and breathing on it. Our day text says the evening conversation changes here, with everyone asking about headaches, breathing and water.
• Night 8, Gorak Shep (5,164 m). The highest night, and the coldest. Our day text says periodic breathing wakes you in fragments and that it is the coldest night. My judgement: it is the night to be most honest with your guide about headache and appetite, because the next morning is a 3 am start.
• Day 9. A start in the dark, 381 metres up to Kala Patthar in about 90 minutes, then 1,560 metres down. The climb is hard, the descent is the relief. Our day text says headaches lift and appetite returns as you drop.

What do the symptoms look like, and how do we tell AMS from being tired?

The CDC Yellow Book describes AMS this way: "headache is the cardinal symptom, usually accompanied by ≥1 of the following: anorexia, dizziness, fatigue, nausea, or, occasionally, vomiting." On a trek, almost everyone is tired and many are off their food, so a headache plus one other symptom is what to watch, not tiredness alone. Researchers score this with the Lake Louise score. The 2018 consensus revision removed disturbed sleep from the questionnaire, because disturbed sleep at altitude is more likely caused by the low oxygen itself than by AMS. That matters on this trek, because you will sleep badly at Gorak Shep whether you are well or not. We write about that in sleeping at altitude. I could not read the full text of the 2018 paper, so I do not quote its scoring thresholds here. In the Cobb study listed below, which used the score, 3 to 4 points counted as mild AMS and 5 or more as moderate to severe.

The two serious conditions are different. The CDC says HACE "presents with neurological findings, particularly altered mental status, ataxia, confusion, and drowsiness". Ataxia means you cannot walk a straight line, and the BMJ article says the features resemble alcohol intoxication. For HAPE the CDC says "initial symptoms include chest congestion, cough, exaggerated dyspnea on exertion, and decreased exercise performance". Dyspnea means breathlessness, so being breathless at rest, or far more than the people around you, is a reason to tell your guide at once, and not to wait for the morning check.

What do our guides check every day?

Our package says each guide carries a first-aid kit with an oximeter, and that our guides hold wilderness first-aid certifications. On the trek they do the following, as written in our itinerary:

• They check every trekker's oxygen saturation with a pulse oximeter in the morning and in the evening.
• They ask every morning how you slept, whether you have a headache and how your appetite is.
• They remind you to drink three to four litres a day. That is our guides' rule of thumb, not a figure from the medical sources above.
• On the Dingboche rest day they take a reading at the top of the acclimatisation hike.
• Above Namche they watch your pace, breathing, colour and walking, not just the numbers.

Be careful about what the oximeter can do, because the experts do not fully agree. A 2024 systematic review in Experimental Physiology (Goves and colleagues) looked at seven studies of 1,406 people ascending between 3,952 and 6,300 metres. It found that falling oxygen saturation during ascent shows a positive predictive relationship with who goes on to develop AMS, but the studies used very different methods and the authors say more work is needed. The 2026 BMJ article is firmer in the other direction: its authors advise against using pulse oximeters to diagnose or confirm altitude illness, because they found no evidence that readings correlate with the presence of the illness, and confusion over readings can delay descent. I take both on board. We carry the oximeter as part of our itinerary, but I treat the reading as one clue and not as the decision. I do not give you a cut-off number here, because I could not find one in the sources I read. The guide decides from your headache, appetite, balance, pace and how you look, and if the symptoms say go down, the reading does not change that.

When do we stop, rest or go down?

The guidance is consistent. The BMJ article says to cease further ascent for mild or moderate AMS symptoms, and to descend for severe AMS symptoms, HACE or HAPE and seek medical attention. The CDC says AMS "improves rapidly with a descent of 300 m (1,000 ft) or more, especially if exertion is minimal", and that for HAPE "in most circumstances, descent is urgent and mandatory". Our own rule, on the package page: if a trekker shows signs of moderate or severe altitude sickness, we descend, and there is no waiting to see. In practice that means:

• Mild symptoms. You tell the guide, and you stop going higher that day, which is the BMJ advice. Whether you rest in place or add a night is a decision for you and your guide, and an extra night changes the cost.
• Moderate or severe symptoms. We go down. On this route that is easy to do: from Gorak Shep (5,164 m) it is a drop of about 750 metres to Dingboche (4,410 m) and 1,179 metres to Pangboche (3,985 m).
• Confusion, loss of balance, or breathlessness at rest. That is an emergency. Our itinerary says a helicopter evacuation can be arranged and is paid for by your travel insurance. The Himalayan Rescue Association also runs an aid post at Pheriche with volunteer doctors in the trekking seasons. Our guide to Pheriche and the aid post covers it.

This is why insurance matters on this trek. Buy it at home, before you fly, and read the wording: you need cover for trekking to 6,000 metres and for emergency helicopter evacuation. A policy with a 3,000 metre ceiling would not cover Dingboche, Lobuche or Gorak Shep. We explain how to check this in which travel insurance covers Everest Base Camp. Our package page asks for a copy of your policy before the trek.

Should I take Diamox?

That is a question for your doctor, and I will not give you a dose. What I can tell you is what the sources say. The CDC says acetazolamide "hastens acclimatization to high-altitude hypoxia". The 2026 BMJ article says it is recommended as the first-line medication for people at moderate or high risk of AMS and HACE, and it notes that these drugs are used off-label for altitude illness. It also gives doses, which I leave to your doctor, who knows your health. Whatever your doctor decides, a tablet does not replace the rest days or the descent rule. Our longer piece, Diamox and altitude medication, goes through the medication in more detail.

Should I add a day, or pick a longer route?

It depends on you, and here is the honest version.

Add a night if you are flying in from sea level with only a night or two in Kathmandu, if you have had altitude trouble before, if you are older or have a heart or lung condition (read our age and health guide), or if you simply cannot afford to be rushed at Gorak Shep. Even then, an extra night is not magic. It helps only if the rest day includes the short hike, and not if you spend it in bed.

The 14-day option. Our guide to the itinerary says I prefer 14 days when people can spare them. I should be clear that we do not list a 14-day Everest Base Camp package. The 12-day trek is the one on the site. If you want a spare night, tell me when you ask for a quote and I will price it. I cannot give you a figure here.

Other routes we run. Two other Everest Base Camp itineraries on the site list one acclimatisation day, at Namche, and none at Dingboche: the 10-day trek with a return by helicopter and the 15-day Everest Base Camp and Gokyo Ri trek. The helicopter return does nothing for the way up, because the altitude exposure is on the walk in. The 15-day trek adds Gokyo, but not a second rest day on the way to Base Camp. For people worried about altitude, the 12-day trek with both rest days is the one I would start with.

The Luxury tier flies you to Lukla by helicopter rather than by plane. You still arrive at 2,860 metres, so it does not change the profile above Lukla.

Choose something else if you know you do poorly above 3,500 metres. Our guide on being scared of altitude looks at lower treks, and our difficulty guide is a fair read before you decide.

Where do our own pages disagree about the heights?

Our package page and older blogs contain figures that do not line up. I use the sleeping heights above and I am correcting the rest.

• Package altitude fields. The Day 8 field says 5,364 metres, which is Base Camp, but you sleep at Gorak Shep (5,164 m). The Day 9 field says 5,545 metres, which is Kala Patthar, but you sleep at Pangboche (3,985 m). The Day 1 field says +1,260 metres, which is the gain from Kathmandu to the Phakding bed, not a gain on the walk. Lukla to Phakding is a descent.
• Kathmandu. The Day 12 field says 1,350 metres and the Day 12 text says 1,400 metres. I show both. The Day 11 text also says 2,600 metres where Lukla is 2,860 metres.
• The first night above 5,000 metres. The Day 8 text says you are above 5,000 metres for the first time, but the Day 6 hike goes to about 5,000. Only the night at Gorak Shep is clearly above 5,000.
• Kala Patthar. We use 5,545 metres. Wikipedia says the commonly listed height is 5,545 to 5,550 metres, but GPS readings in 2006 and 2008 gave 5,643 and 5,644.5 metres, and it lists 5,644.5 in its infobox. Wikipedia says trekkers climb to a local high point on the Pumori ridge and not the true summit, which accounts for the differences. I keep our figure and say so.
• Dingboche. We use 4,410 metres. Wikipedia's Dingboche page agrees, but its Everest Base Camp page gives 4,260 metres, so Wikipedia disagrees with itself.
• Twelve days above 3,000 metres. The Day 11 text says you have spent twelve days above 3,000 metres. By the itinerary you sleep above 3,000 metres on nine nights, and Lukla and Phakding are below it.
• The night after Kala Patthar. The 12-day trek sleeps at Pangboche (3,985 m). The 10-day and 15-day packages and our Pheriche guide use Pheriche (4,250 m), and our altitude sickness guide's schedule table gives 4,371 metres and numbers its days from Kathmandu, so its day numbers are one different from the itinerary. Check which one applies to your trek.

If a number on this page differs from what your guide says on the trail, believe the guide, and tell me so I can correct the page.

The short version

Our 12-day Everest Base Camp trek has two rest days, at Namche and Dingboche, and the sleeping height rises from 2,610 metres to 5,164 metres. By my arithmetic three nights are over the 500 metre guideline, the Namche night by the most, and the plan relies on the rest days and on the guide to make up for that. The serious cases in the Pheriche series began high on the route, around Thukla and Lobuche, so the stretch from Dingboche to Gorak Shep is where I ask you to be most honest with your guide. If you have a headache plus nausea, dizziness or heavy fatigue, tell him that evening. Our rule is simple: moderate or severe symptoms mean we go down. Buy insurance at home that covers trekking to 6,000 metres and helicopter evacuation, talk to your doctor about medication, and ask me for a spare night if you can afford the days. For more on the biology, start with our guides to altitude sickness, acclimatisation and what happens on an acclimatisation day, and for the village that sets the night-by-night picture, read about Dingboche and Gorak Shep. To look at the trek itself, see our 12-day Everest Base Camp trek, or message me on WhatsApp on +977 9810351300.

Sources

• Our live 12-day Everest Base Camp itinerary and package page (heights, walking times, guide checks, insurance wording), read 4 October 2026. The Nangkartshang height of about 5,000 metres and the Lobuche height of 4,940 metres are from our own itinerary only; I could not confirm them from an outside source.
• CDC Yellow Book, "High-Altitude Travel and Altitude Illness", last updated 23 April 2025, cdc.gov/yellow-book.
• Adhikari S, Zimmer R, Brugger H, Bajracharya N, Basnyat B. "Prevention of altitude illness in adults: preparing people for travel to high altitude". BMJ 2026, doi 10.1136/bmj-2026-100532 (open access).
• Roach RC and others. "The 2018 Lake Louise Acute Mountain Sickness Score". High Altitude Medicine and Biology, 2018, doi 10.1089/ham.2017.0164 (abstract only read).
• Luks AM and others. Wilderness Medical Society clinical practice guidelines for the prevention and treatment of acute altitude illness, 2019 update (abstract only read).
• Haunolder M and others. "Cardiovascular Risk Profiles and Pre-Existing Health Conditions of Trekkers in the Solu-Khumbu Region, Nepal". International Journal of Environmental Research and Public Health, 2022.
• Cerfontaine C and others. "Companion Rescue and Risk Management of Trekkers on the Everest Trek, Solo Khumbu Region, Nepal". International Journal of Environmental Research and Public Health, 2022.
• Jones BE and others. "Management of high altitude pulmonary edema in the Himalaya: a review of 56 cases presenting at Pheriche medical aid post". Wilderness and Environmental Medicine, 2013.
• Cobb AB and others. "Physiological responses during ascent to high altitude and the incidence of acute mountain sickness". Physiological Reports, 2021.
• Goves JSL and others. "Pulse oximetry for the prediction of acute mountain sickness: A systematic review". Experimental Physiology, 2024.
• Wikipedia pages for Kala Patthar, Dingboche and Everest Base Camp, read 4 October 2026, for cross-checking heights only.

About The Everest Holiday

We are a family company in Kathmandu, three generations of family guides, registered in 2016 and a member of the Trekking Agencies' Association of Nepal, number 1586. When you book with us you deal with the family, not a call centre, and the guide who meets you works for the same people who answered your first message.

Written by Shreejan Simkhada, CEO of The Everest Holiday, from a family of three generations of family guides. TAAN Member #1586.