Altitude Sickness Risk Calculator – Assess Your Risk of AMS Before Climbing

Stay safe at high altitude with our Altitude Sickness Risk Calculator. Enter your ascent rate, target altitude, and health risk factors to evaluate your Acute Mountain Sickness (AMS) risk level and get acclimatization recommendations.

Target Altitude (meters)

Daily Ascent Rate (meters/day)

Recommended: 300-500m/day above 3000m

Sleep Altitude (meters)

Previous High Altitude Experience

Risk Assessment

Enter altitude details and click Calculate to assess risk

How to Use This Altitude Sickness Risk Calculator

Enter your climb details

Input your target altitude, daily ascent rate, and planned sleep altitude. Be realistic about your ascent speed – rushing increases risk significantly.

Add your experience and health info

Select your previous high altitude experience level. While there are no specific health condition checkboxes, know that pre-existing heart or lung conditions increase your risk.

Review your risk assessment

The calculator shows your risk level, expected symptoms, required acclimatization days, and personalized safety recommendations. Use this to plan a safer ascent.

Understanding Altitude Sickness

What is altitude sickness?

Altitude sickness, also called acute mountain sickness (AMS), is your body's negative response to low oxygen levels at high elevation. As you climb higher, the air pressure drops and each breath delivers less oxygen to your tissues. Your body needs time to adapt – a process called acclimatization. Without sufficient acclimatization, you get sick.

Why does it happen?

Atmospheric pressure decreases with altitude. At sea level, air pressure is about 1013 hPa. At 5000 meters, it drops to roughly 540 hPa – nearly half. Even though oxygen still makes up 21% of the air, the lower pressure means fewer oxygen molecules per breath. Your blood oxygen saturation drops, and organs start struggling. The brain, lungs, and cardiovascular system are hit hardest.

Types of altitude sickness

AMS (Acute Mountain Sickness)

The mildest and most common form. Affects 25-85% of climbers above 3000m. Symptoms include headache, nausea, fatigue, and dizziness. Uncomfortable but rarely life-threatening if managed properly.

HAPE (High Altitude Pulmonary Edema)

Fluid builds up in your lungs. You can't breathe properly even at rest. This is life-threatening and requires immediate descent. HAPE can develop within hours and kills if ignored.

HACE (High Altitude Cerebral Edema)

Fluid accumulates in the brain, causing swelling. Symptoms include confusion, loss of coordination, and altered consciousness. HACE is fatal without immediate descent and medical treatment.

Who is at risk?

Anyone can get altitude sickness – fitness level doesn't protect you. Young, healthy athletes get hit just as hard as out-of-shape climbers. The only reliable predictor is your ascent rate and previous acclimatization. Some people are genetically more susceptible, but you won't know until you're up there. Previous experience helps you recognize symptoms early, which makes a real difference.

Altitude Zones and Risk Levels

Zone	Meters	Feet	Risk Level
Low altitude	0-1,500m	0-5,000ft	Minimal risk
Moderate altitude	1,500-2,500m	5,000-8,000ft	Low risk
High altitude	2,500-3,500m	8,000-11,500ft	Moderate risk
Very high altitude	3,500-5,500m	11,500-18,000ft	High risk
Extreme altitude	5,500m+	18,000ft+	Very high risk

Note: Risk increases significantly when ascending faster than recommended rates. The zones above assume proper acclimatization protocols are followed.

Symptoms of Altitude Sickness

Mild Symptoms (AMS)

• Headache (the most common symptom – often throbbing)
• Nausea or loss of appetite
• Fatigue and weakness
• Dizziness or lightheadedness
• Difficulty sleeping

Action: Rest at current altitude until symptoms resolve. Do not ascend further.

Moderate Symptoms

• Severe, persistent headache (not relieved by painkillers)
• Vomiting
• Shortness of breath even at rest
• Rapid heartbeat
• Reduced urine output

Action: Descend 500-1000m immediately. Consider acetazolamide. Monitor closely.

Severe Symptoms (HAPE/HACE) – Medical Emergency

• Confusion or altered mental state
• Persistent dry cough (may produce pink, frothy sputum with HAPE)
• Inability to walk in a straight line (ataxia)
• Extreme fatigue or inability to get out of bed
• Gurgling breath sounds
• Blue or gray lips/fingernails (cyanosis)

Action: DESCEND IMMEDIATELY. This is life-threatening. Evacuate to hospital. Do not wait for morning. Do not leave the person alone.

Prevention Strategies

Ascend gradually

Above 3,000 meters, limit your daily gain in sleeping altitude to 300-500 meters. This is the single most important prevention strategy. Your body needs time to produce more red blood cells and adjust to lower oxygen levels.

Plan rest days

Take a rest day every 3-4 days during your ascent. On rest days, you can hike higher during the day but return to sleep at the same altitude. This "climb high, sleep low" approach aids acclimatization.

Stay hydrated

Drink 3-4 liters of water per day at altitude. You lose more fluid through respiration in dry mountain air. Dehydration worsens altitude sickness symptoms. Monitor urine color – it should be light yellow.

Avoid alcohol initially

Skip alcohol for the first 48-72 hours at altitude. Alcohol depresses breathing during sleep and worsens dehydration. Both effects increase altitude sickness risk.

Consider acetazolamide (Diamox)

This prescription medication speeds acclimatization by stimulating breathing. Typical dose: 125-250mg twice daily, starting one day before ascent. Consult a doctor – it's not suitable for everyone (especially those with sulfa allergies).

Eat well

Maintain a high-carbohydrate diet at altitude. Carbs require less oxygen to metabolize than fats or proteins. Don't skip meals even if you've lost your appetite – it's a common AMS symptom.

Frequently Asked Questions

What causes altitude sickness?

Altitude sickness is caused by reduced atmospheric pressure at high elevation, which means less oxygen per breath. Your blood oxygen saturation drops, and your body can't deliver enough oxygen to tissues and organs. The brain and lungs are especially sensitive. If you ascend faster than your body can adapt, you get sick.

How can I prevent altitude sickness?

The best prevention is slow ascent. Above 3,000 meters, gain no more than 300-500 meters of sleeping altitude per day. Take rest days every 3-4 days. Stay well hydrated, avoid alcohol early on, and consider acetazolamide if you have a history of AMS. Most importantly – listen to your body and don't push through symptoms.

Who is most at risk for altitude sickness?

Everyone is at risk – fitness, age, and gender don't provide reliable protection. The biggest risk factors are rapid ascent, high sleeping altitude, and previous history of altitude sickness. People living at sea level are more susceptible than those who live at moderate altitude. Some individuals appear genetically prone to AMS, but there's no way to know before you're at altitude.

How long does altitude sickness last?

Mild AMS typically resolves within 24-48 hours if you rest at the same altitude. Symptoms should improve as your body acclimatizes. If symptoms persist beyond 48 hours or worsen, you need to descend. Severe forms (HAPE, HACE) require immediate descent and medical care – they won't resolve on their own and can be fatal within hours if ignored.

When should I descend?

Descend immediately if: symptoms worsen despite rest, you develop moderate symptoms (severe headache, vomiting, breathlessness at rest), or you show any signs of HAPE or HACE (confusion, cough, inability to walk straight). Don't wait for morning. Don't try to "sleep it off." A 500-1000 meter descent often brings rapid relief. Your ego isn't worth dying for – there will be other climbs.

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