Normal Blood Oxygen (SpO2) at Altitude — Calculator & Reference Chart
Enter your pulse oximeter reading and altitude to instantly know if your SpO2 is normal for that elevation. Altitude-adjusted thresholds: ≥95% at sea level, ≥93% at 1,500 m, ≥90% at 2,500 m, ≥88% above 3,500 m. Based on published altitude-physiology research.
See step-by-step calculation
When to use this calculator
- Hikers and trekkers checking their pulse oximeter readings at altitude (Kilimanjaro, Machu Picchu, Everest Base Camp)
- Travelers who flew to a high-altitude city (Cusco at 3,400 m, La Paz at 3,650 m, Lhasa at 3,656 m) and want to know if their SpO2 is acceptable
- Athletes training at altitude who need objective feedback on acclimatization progress
- Nurses and paramedics doing quick triage at mountain rescue posts or high-altitude clinics
Minimum normal SpO2 by altitude band
| Altitude band | Example locations | Minimum normal SpO2 | Classification if below |
|---|---|---|---|
| 0 – 1,500 m (0 – 4,900 ft) | Buenos Aires (25 m), Lima (154 m), New York (10 m) | ≥ 95% | Mild hypoxia < 94%; Significant < 90% |
| 1,500 – 2,500 m (4,900 – 8,200 ft) | Mexico City (2,240 m), Nairobi (1,795 m), Denver (1,609 m) | ≥ 93% | Mild hypoxia < 92%; Significant < 88% |
| 2,500 – 3,500 m (8,200 – 11,500 ft) | Bogotá (2,625 m), Quito (2,850 m), Cusco (3,400 m) | ≥ 90% | Mild hypoxia < 89%; Significant < 85% |
| Above 3,500 m (above 11,500 ft) | La Paz (3,650 m), Lhasa (3,656 m), Everest Base Camp (5,364 m) | ≥ 88% | Mild hypoxia < 87%; Significant < 83% |
Source: Wilderness Medical Society — Practice Guidelines for High-Altitude Illness; WHO Environmental Health Criteria 111. Thresholds are for healthy adults at rest; cold fingers or peripheral vasoconstriction can lower readings by 2–4%.
How it works
Normal SpO2 by altitude — reference table
| Altitude band | Example locations | Minimum normal SpO2 |
|---|---|---|
| Sea level to 1,500 m | Buenos Aires (25 m), Lima (154 m), New York (10 m) | ≥ 95% |
| 1,500 m – 2,500 m | Mexico City (2,240 m), Nairobi (1,795 m), Denver (1,609 m) | ≥ 93% |
| 2,500 m – 3,500 m | Bogotá (2,625 m), Quito (2,850 m), Cusco (3,400 m) | ≥ 90% |
| Above 3,500 m | La Paz (3,650 m), Lhasa (3,656 m), EBC (5,364 m) | ≥ 88% |
How the calculator classifies your reading
Once your altitude threshold is looked up, your SpO2 is placed in one of three zones:
Why SpO2 drops with altitude
At altitude, atmospheric pressure decreases, so each breath delivers fewer oxygen molecules even though the air is still 21% oxygen. The partial pressure of oxygen (PO₂) at sea level is about 159 mmHg; at 3,600 m it drops to roughly 100 mmHg. The hemoglobin–oxygen dissociation curve means this translates to a measurable fall in SpO2.
With acclimatization (hours to days at altitude), the body compensates: breathing rate increases, more red blood cells are produced, and 2,3-BPG levels rise to help unload oxygen to tissues. This is why the same SpO2 that would alarm a doctor at sea level can be perfectly acceptable after 24–48 hours at altitude.
Pulse oximeter accuracy notes
Fingertip pulse oximeters measure SpO2 using two wavelengths of light through the finger. They are accurate to ±2% under normal conditions (well-perfused, warm fingers, no nail polish). At altitude, cold fingers and peripheral vasoconstriction can depress the reading further. If your result seems unexpectedly low: warm your hands, reposition the device, and take 2–3 measurements at rest.
This calculator is a reference tool, not a medical device. If you have symptoms (severe headache, confusion, ataxia, cyanosis) do not wait for a second reading — descend and seek care.
Example: First day in Cusco (3,400 m / 11,150 ft)
Frequently asked questions
What SpO2 is normal at sea level?
I'm in Cusco (3,400 m) with 89% SpO2. Is that an emergency?
What SpO2 requires immediate descent at high altitude?
Does the reading differ between day 1 and day 3 at altitude?
My oximeter reads 92% at 2,000 m but I feel fine. Should I worry?
Can cold fingers give a falsely low SpO2 reading?
What's the lowest SpO2 ever recorded in a healthy person at extreme altitude?
Does altitude affect SpO2 differently in people with lung disease (COPD, asthma)?
Is SpO2 the same as the PO₂ measured in an arterial blood gas?
What is the normal SpO2 for children at altitude?
Sources & references
- Grocott et al. — Arterial Blood Gases and Oxygen Content in Climbers on Mount Everest (NEJM 2009)
- Wilderness Medical Society — Practice Guidelines for High-Altitude Illness
- WHO — High-altitude and Human Health (Environmental Health Criteria 111)
- MedlinePlus — Pulse Oximetry (U.S. National Library of Medicine)
- NIH NHLBI — What Is Pulse Oximetry?
- Lancet Global Health — SpO2 reference values at altitude in healthy children
Methodology & trust
Calculadora de salud revisada por el equipo editorial de Hacé Cuentas, contrastada con Grocott et al. — Arterial Blood Gases and Oxygen Content in Climbers on Mount Everest (NEJM 2009), según nuestra política editorial y metodología.
Última revisión: June 20, 2026. Los parámetros se verifican periódicamente con las fuentes citadas.
Calculations run 100% in your browser. We do not store or transmit your data.
Indicative results. For critical decisions, consult a professional.
Rodríguez, M. (2026). Normal Blood Oxygen (SpO2) at Altitude — Calculator & Reference Chart. Hacé Cuentas. https://hacecuentas.com/blood-oxygen-saturation-spo2-altitude
Contenido bajo licencia CC-BY 4.0 — reutilizable citando la fuente con enlace a Hacé Cuentas.