Altitude Acclimatization Planner for Treks – Sleeping Altitude & Rest Days

Altitude acclimatization: plan your sleeping altitudes

This altitude acclimatization planner helps you lay out the nights of a high-altitude trek, such as a Himalayan trek in Nepal or India, Ladakh, the Andes or Kilimanjaro, so that the altitude where you sleep rises slowly enough. You can either build a plan from a starting altitude and a target, or paste the sleeping altitudes of an itinerary you already have and see which nights go beyond the guidance.

This is information only and not medical advice. It applies published rules of thumb. It cannot tell whether you are acclimatising well, and it does not replace advice from a doctor or a travel clinic, especially if you have a heart or lung condition, are pregnant or have had altitude illness before.

How to use the Altitude Acclimatization Planner

1. Choose Build a plan or Check my itinerary, and metres or feet.
2. For a plan, enter your first night’s sleeping altitude, the highest sleeping altitude you want, and the most you will climb in a night (the guidance is 500 m).
3. For a check, list the altitude where you sleep each night, in order.
4. Choose a rest day after every 3 or 4 ascent nights above 3,000 m.
5. Read the table, treat any night marked Check as a prompt to add a rest night or shorten the climb, and copy the plan for your guide or doctor.

Altitude Acclimatization Planner features

The guidance used, with sources

The rules come from the Wilderness Medical Society’s clinical practice guidelines for the prevention and treatment of acute altitude illness (2019 update). As summarised by the CDC Yellow Book chapter on high-altitude travel, and by the American Family Physician summary (2020), they advise: avoid going from a low altitude to a sleeping altitude of 2,750 m (9,000 ft) or more in a single day; once above 3,000 m (9,800 ft), increase the sleeping altitude by no more than 500 m (1,650 ft) per night; and add an extra night to acclimatise for every 1,000 m (3,300 ft) of sleeping altitude gained. Advice from UK TravelHealthPro and BMJ Best Practice, citing the same guideline, adds a rest day at the same altitude every three or four days above 3,000 m. All were read on 24 October 2026; check the current text before you travel.

The planner uses these as follows. Below 2,700 m it allows a larger first step; above that it adds at most your chosen gain per night. After three (or four) ascent nights above 3,000 m, or after 1,000 m of gain since the last rest night, it inserts a rest night at the same altitude. The 1,500 m used by the checker for “low altitude” is this page’s own reading of the guideline, so a night that is flagged for it deserves a second look rather than an automatic change.

Symptoms and what to do

Acute mountain sickness usually starts with a headache, often with nausea, vomiting, tiredness, dizziness or poor sleep, some hours after arriving at a new height. Do not go higher until the symptoms are gone. If they worsen, descend, and descend at once with confusion, loss of balance, breathlessness at rest or a wet cough, which can be signs of brain or lung swelling. Medicines such as acetazolamide may be prescribed for prevention; that is a decision for a doctor, not this page. Fitness does not protect you, so plan the same for everyone in a group, and keep the slowest member’s needs in mind. For heights along a route, use the elevation finder.