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Altitude Sickness Risk Calculator

Estimate your risk of Acute Mountain Sickness based on ascent rate and target altitude

Calculator

The Altitude Sickness Risk Calculator estimates your likelihood of experiencing Acute Mountain Sickness (AMS) based on your planned ascent profile. AMS affects roughly 25% of trekkers above 2,500 m and up to 50% above 4,000 m, making it the most common health hazard in mountain travel. Symptoms range from headache and nausea to life-threatening conditions like High Altitude Cerebral Edema (HACE) and High Altitude Pulmonary Edema (HAPE).

Enter your starting altitude, target altitude, and the number of ascent days. The calculator evaluates two independent risk factors: the altitude zone you will enter (the higher you go, the lower the oxygen partial pressure) and your daily altitude gain (how fast you ascend through those zones). The widely accepted guideline of ascending no more than 300-500 m per day in sleeping altitude above 2,500 m forms the basis of the risk model.

Results include a color-coded risk level (Low, Moderate, High, Very High), practical acclimatization tips, and preset scenarios for popular high-altitude destinations like Everest Base Camp, Kilimanjaro, Mont Blanc, and Machu Picchu. A unit toggle switches seamlessly between meters and feet.

This tool is for educational purposes only. Individual susceptibility to altitude sickness varies widely and is not predictable from fitness level or previous experience. Always consult a travel medicine physician before high-altitude travel.

So funktioniert es

  1. Enter your starting altitude (the elevation where you begin your trek)
  2. Enter your target altitude (the highest point you plan to reach)
  3. Enter the number of ascent days for the climb
  4. Toggle between meters and feet using the unit switcher
  5. View the calculated daily altitude gain, altitude zone risk, and overall risk level
  6. Read the personalized acclimatization recommendations
  7. Try the preset scenarios (Everest BC, Kilimanjaro, Mont Blanc, Machu Picchu) for instant results
  8. Adjust the inputs to explore how adding rest days or splitting the ascent changes your risk profile

Ausprobieren

Meters Feet
Presets:
Daily Altitude Gain
Altitude Zone
Overall Risk
Low Very High

Acclimatization Tips

Disclaimer: This calculator provides general estimates only. Individual susceptibility to altitude sickness varies widely. Consult a doctor before high-altitude travel.

Anwendungsfälle

Verwandte Begriffe

Akklimatisierung Todeszone

How to Use

  1. 1
    Enter altitude data

    Enter your starting altitude, target summit altitude, and the number of ascent days.

  2. 2
    Review risk level

    Review the calculated daily altitude gain and altitude zone to see your risk level.

  3. 3
    Follow acclimatization tips

    Follow the acclimatization tips or try preset scenarios for popular high-altitude destinations.

About

Acute Mountain Sickness (AMS) is the most common medical condition encountered by trekkers, climbers, and travelers at high altitude. It is caused by the body's inability to acclimatize quickly enough to the reduced atmospheric pressure and lower oxygen levels found at elevation. At sea level, atmospheric pressure is approximately 1,013 hPa and the oxygen concentration is 20.9%. At 5,500 m, pressure drops to roughly 505 hPa — meaning each breath delivers about half the oxygen molecules compared to sea level.

The human body has remarkable adaptive mechanisms: increased breathing rate, higher heart rate, increased red blood cell production, and changes in hemoglobin's oxygen affinity. However, these adaptations take time — typically 1-3 days per 1,000 m gained above 2,500 m. When ascent outpaces acclimatization, fluid leaks into the brain (HACE) or lungs (HAPE), both of which can be fatal without prompt descent.

The Wilderness Medical Society recommends ascending no more than 500 m per day in sleeping altitude above 3,000 m, with a rest day every 3-4 days. The Lake Louise Consensus Group scoring system is the standard diagnostic tool, evaluating headache, gastrointestinal symptoms, fatigue, and dizziness on a 0-3 scale. A score of 3 or higher with headache confirms AMS diagnosis.

Pharmacological prevention includes acetazolamide (Diamox), which accelerates acclimatization by promoting bicarbonate diuresis, and dexamethasone for those who cannot tolerate acetazolamide. Both require a prescription and should be discussed with a travel medicine physician before departure.

Popular high-altitude destinations vary dramatically in risk. Machu Picchu (2,430 m) is below the typical AMS threshold and rarely causes problems. Kilimanjaro (5,895 m) sees AMS rates of 50-75% depending on route and duration. Everest Base Camp (5,364 m) on the classic 12-14 day trek has lower AMS rates (around 25%) because the gradual approach allows natural acclimatization. Mont Blanc (4,808 m) is often climbed in 2 days from Chamonix, making it one of the riskier popular peaks due to the rapid ascent profile.

FAQ

What is altitude sickness (AMS)?
Acute Mountain Sickness (AMS) is a condition caused by reduced oxygen availability at high altitude. Symptoms include headache, nausea, fatigue, dizziness, and disturbed sleep. It typically begins 6-12 hours after reaching altitudes above 2,500 m (8,200 ft). AMS can progress to life-threatening conditions like HACE (cerebral edema) and HAPE (pulmonary edema) if ascent continues without acclimatization.
How fast can I safely ascend at high altitude?
Above 2,500 m (8,200 ft), the widely accepted guideline is to increase your sleeping altitude by no more than 300-500 m (1,000-1,600 ft) per day. A rest day every 3-4 days of ascent further reduces risk. These guidelines apply regardless of fitness level, as altitude sickness susceptibility is largely genetic and cannot be predicted from physical conditioning.
Does physical fitness prevent altitude sickness?
No. Physical fitness does not protect against AMS. Highly fit athletes are sometimes more susceptible because they tend to ascend faster. The primary prevention is controlled ascent rate and proper acclimatization. Medications like acetazolamide (Diamox) can help prevent AMS when prescribed by a doctor.
At what altitude does altitude sickness start?
AMS symptoms can begin as low as 2,000 m (6,600 ft), though most cases occur above 2,500 m (8,200 ft). The risk increases significantly above 3,500 m (11,500 ft), where up to 50% of people experience some symptoms. Above 5,500 m (18,000 ft), known as the extreme altitude zone, nearly everyone is affected without proper acclimatization.
What should I do if I get altitude sickness symptoms?
Stop ascending immediately. If symptoms are mild (headache, mild nausea), rest at your current altitude until symptoms resolve. If symptoms worsen or include confusion, difficulty walking, or breathlessness at rest, descend at least 500-1,000 m immediately. Descent is the definitive treatment for AMS. Seek medical attention if symptoms are severe.

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