The Ladakh altitude ladder: why the order of your days matters more than the distance

The number that is not on your itinerary

Ladakh tours get sold on distance and on photographs of passes. Neither is what makes riders ill. What makes riders ill is where they slept the night before, and the night before that. Altitude medicine has been clear on this for years, and almost no itinerary shows you the figure.

What the guideline actually says

The Wilderness Medical Society updated its clinical practice guidelines for acute altitude illness in 2024. Two numbers carry most of the weight. Above 3,000 m, do not increase your sleeping elevation by more than 500 m in a day. Take a rest day, meaning no gain in sleeping elevation at all, every three to four days.

The same document states the point of this page in its own words: in planning the rate of ascent, the altitude at which someone sleeps is considered more important than the altitude reached during waking hours. That is the primary source, not my opinion.

Real mountains do not come in 500 m steps, and the guideline allows for that. Where the terrain forces a bigger jump, it asks for acclimatisation days either side, so that the total gain divided by the number of ascent days still comes out under 500 m a day. That averaging test is the one to run on an itinerary you have been sent.

Two things people attach to this guideline that are not in it

If you have read around this subject you will have met two claims credited to the Wilderness Medical Society. Neither is in the 2024 document. I searched the full text rather than the summaries.

• Climb high, sleep low. The phrase does not appear. It is long-standing mountaineering practice and it is not a finding of this guideline, so do not let a page cite the guideline for it.
• The high, very high and extreme altitude bands, usually given as 1,500 to 3,500 m, 3,500 to 5,500 m and above 5,500 m. The guideline does not define them. It says close to the opposite: recognising the difficulty in defining a fixed threshold, it recommends an approach that does not depend strictly on the altitude you are travelling to.

I raise it because both claims turn up on pages that look authoritative, often with a tidy table of metres per day that nobody can source. A page willing to tell you what its own source does not say is easier to trust on what it does.

Leh breaks the rule before you have ridden anything

Leh sits at 3,500 m. Fly in and you have gone from sea level to above the 3,000 m threshold in a morning, and you are sleeping there tonight. The US Centers for Disease Control puts a day-one sleeping altitude above 3,400 m in its highest risk category, and says rates of altitude illness approach 50 per cent where travellers arrive by air at that sort of height.

How you arrive matters, not only where you end up. A 2023 review in the Journal of Travel Medicine pooled twelve studies covering just over 11,000 people across nineteen different altitudes. Incidence rose with altitude in every group, but the slope was about four and a half times steeper for people who flew in than for people who walked or drove up. That works out at roughly 11.5 per cent more acute mountain sickness per 100 m for air arrivals, against 2.1 per cent for slower ascents.

So if your dates allow the road, take the road. If they do not, your first two days in Leh are not spare time to be spent sightseeing at height.

The 48 hours Ladakh asks for, and the muddle in the official record

There is a rule. Every tourist arriving in Leh is asked to complete at least 48 hours of acclimatisation before travelling to higher areas, and the district administration names Khardung La and Pangong as the places you do not go first.

It came out of a bad year. By 10 June 2022, fifteen tourists had died in Ladakh, eleven of them from altitude-related causes, four of those in the first ten days of that June. The Hill Council took the decision on 16 June 2022.

Now the part that does not get written down. The government does not agree with itself on the number. The Leh district site, the tourism department web page and the permit portal all say at least 48 hours. The tourism department's own PDF advisory says a minimum of 24. The police site says 24 to 48. One government, four documents, two answers. Plan on 48: it is the stricter figure, it is what three of the four say, and nothing bad happens to you for resting longer.

One line in that tourism advisory is worth quoting because riders get it backwards. Road travel, it says, does not aid in acclimatization and can exacerbate altitude sickness. A long drive on your first day out of Leh is not the gentle option it looks like. The same document asks visitors not to go to Pangong or any mountain pass within one to two days of arriving.

Where you sleep, against where you ride

Read the columns separately. The right-hand column is what people photograph. The left-hand column is what decides how they feel. A pass at 5,359 m crossed at eleven in the morning and dropped off by two is a few hours of load. A bed at 4,500 m is fourteen hours of it, most of them asleep.

Our own Changthang section is built on that difference. Hanle at 4,500 m is the bed. Umling La at 5,798 m is an out-and-back from it, ridden early and descended the same day, with no night spent up there. That is not caution for its own sake. It is the only way to reach that height without breaking the sleeping-altitude rule on the way.

The government does not agree with itself about how high these places are

Khardung La first. The Leh district administration publishes 18,379 ft, which it gives as 5,602 m, and that is roughly what the board at the pass claims too. The Press Information Bureau, announcing Border Roads Organisation work in August 2021, states plainly that the Khardung La Pass in Leh is at an altitude of 17,582 ft, about 5,359 m. Same government, two documents, some 800 ft apart.

Umling La has a gap of its own. That same 2021 release gives 19,300 ft. Guinness World Records, which surveyed the road in November 2021, records 5,798.251 m, or 19,024 ft. Neither is a typo. None of this changes the riding, and I am not going to tell you which figure is correct, because I do not know. It changes what you do when a page quotes you an altitude to three decimal places and does not say where it came from. Every number on this page has its source at the bottom, including the ones that disagree with each other.

What we do about it

Our Ladakh route opens with a day that has no riding in it. Leh at 11,480 ft, bike inspection, permit processing, a walk into town, nothing else. That day does more for the following fortnight than anything else on the itinerary. Oxygen travels in the back-up vehicle, a rider who is unwell travels in it instead of on the bike, and the route is laid out so that losing height is always available. You do not need to book with us to use any of that. Run the five checks on whoever you are talking to.

The number I cannot give you

You will want your odds. I cannot give them to you honestly, and nor can anyone else. Nobody has published a study measuring altitude sickness among leisure tourists in Leh. The Leh figures that exist come from military cohorts, young and screened and already on an acclimatisation or drug protocol, and they run from about 3 per cent to 13 per cent. A study of 2,385 tourists at Lhasa, which sits at a similar height, found 36.7 per cent. Neither population is yours.

So the honest position is this. The risk is real enough that an administration changed its rules over it after a run of deaths, and nobody has measured it for someone like you. Plan against the guideline rather than against a percentage.