Altitude Acclimatization Calculator
Calculate how many days you need to acclimatize before reaching high altitude.
Plan your trek to avoid altitude sickness.
Altitude sickness (Acute Mountain Sickness, AMS) occurs when you ascend faster than your body can adapt to lower oxygen levels. The risk increases significantly above 2,500 m.
Ascent rate guidelines:
- Below 2,500 m: No acclimatization needed for most people
- 2,500–3,500 m: Ascend no faster than 300–500 m per day of sleeping altitude
- Above 3,500 m: Ascend no faster than 300 m per day of sleeping altitude
- Rest day rule: Take 1 rest day for every 1,000 m gained above 3,000 m
The golden rule: “Climb high, sleep low.” You can ascend higher during the day as long as you descend to sleep at a lower altitude. This is the core principle of acclimatization on Himalayan expeditions.
Common trekking altitudes:
- Machu Picchu, Peru: 2,430 m (some acclimatization helpful)
- Everest Base Camp, Nepal: 5,364 m (8–12 day trek)
- Kilimanjaro summit, Tanzania: 5,895 m
- Aconcagua summit, Argentina: 6,961 m
Symptoms of AMS: Headache, nausea, fatigue, dizziness, poor sleep. Mild symptoms are common — the danger comes from HACE (brain) or HAPE (lungs) which are life-threatening and require immediate descent.
Medications: Acetazolamide (Diamox) can aid acclimatization when prescribed. Consult a travel health doctor before use. It is not a substitute for proper acclimatization.