Oxygen at Altitude Calculator
Enter an elevation to see how much oxygen a breath holds there compared with sea level. The air is always 20.9% oxygen; higher up there is less air.
Oxygen per breath
—%
of the sea-level amount ·
- Effective oxygen
- % at sea level
- Oxygen partial pressure
- mmHg
- kPa · sea level 159 mmHg
Standard-atmosphere estimate for dry air. Not medical advice. Sources below.
Health note
This page describes the air, not your body: how a person responds to altitude varies, and blood oxygen depends on far more than elevation. For travel to high elevation, read theCDC Yellow Book chapter on high-altitude travel and altitude illnessand talk to a doctor, especially with heart or lung conditions or during pregnancy. This calculator is general information, not medical advice.
Oxygen in high US cities and well-known places
Elevations from each place's page on this site (USGS at the city center; published summit figures for mountains).
| Place | Elevation | Oxygen per breath | Effective O₂ |
|---|---|---|---|
| Denali, AK | 20,310 ft (6,191 m) | 45% | 9.5% |
| Mount Whitney, CA | 14,505 ft (4,421 m) | 58% | 12.1% |
| Pikes Peak, CO | 14,115 ft (4,302 m) | 58% | 12.2% |
| La Paz, Bolivia | 11,977 ft (3,651 m) | 64% | 13.3% |
| Mammoth Lakes, CA | 7,873 ft (2,400 m) | 75% | 15.6% |
| Big Sky, MT | 7,220 ft (2,201 m) | 77% | 16.0% |
| Park City, UT | 7,014 ft (2,138 m) | 77% | 16.2% |
| Santa Fe, NM | 6,997 ft (2,133 m) | 77% | 16.2% |
| Big Bear Lake, CA | 6,752 ft (2,058 m) | 78% | 16.3% |
| South Lake Tahoe, CA | 6,238 ft (1,902 m) | 79% | 16.6% |
| Jackson, WY | 6,238 ft (1,901 m) | 79% | 16.6% |
| Cheyenne, WY | 6,091 ft (1,857 m) | 80% | 16.7% |
| Colorado Springs, CO | 6,009 ft (1,832 m) | 80% | 16.8% |
| Truckee, CA | 5,817 ft (1,773 m) | 81% | 16.9% |
| Denver, CO | 5,276 ft (1,608 m) | 82% | 17.3% |
| Fort Collins, CO | 5,004 ft (1,525 m) | 83% | 17.4% |
| Boston, MA | 48 ft (15 m) | 100% | 20.9% |
Oxygen by elevation
| Elevation | Oxygen per breath | Effective O₂ | O₂ partial pressure |
|---|---|---|---|
| 0 ft (0 m) | 100% | 20.9% | 159 mmHg |
| 1,000 ft (305 m) | 96% | 20.2% | 154 mmHg |
| 2,000 ft (610 m) | 93% | 19.5% | 148 mmHg |
| 3,000 ft (914 m) | 90% | 18.8% | 143 mmHg |
| 4,000 ft (1,219 m) | 86% | 18.1% | 137 mmHg |
| 5,000 ft (1,524 m) | 83% | 17.4% | 132 mmHg |
| 6,000 ft (1,829 m) | 80% | 16.8% | 128 mmHg |
| 7,000 ft (2,134 m) | 77% | 16.2% | 123 mmHg |
| 8,000 ft (2,438 m) | 74% | 15.6% | 118 mmHg |
| 9,000 ft (2,743 m) | 71% | 15.0% | 114 mmHg |
| 10,000 ft (3,048 m) | 69% | 14.4% | 109 mmHg |
| 12,000 ft (3,658 m) | 64% | 13.3% | 101 mmHg |
| 14,000 ft (4,267 m) | 59% | 12.3% | 94 mmHg |
| 16,000 ft (4,877 m) | 54% | 11.4% | 86 mmHg |
| 18,000 ft (5,486 m) | 50% | 10.5% | 80 mmHg |
| 20,000 ft (6,096 m) | 46% | 9.6% | 73 mmHg |
| 25,000 ft (7,620 m) | 37% | 7.8% | 59 mmHg |
| 30,000 ft (9,144 m) | 30% | 6.2% | 47 mmHg |
Elevation where a breath holds a given share of the sea-level oxygen: 90% at 2,890 ft (881 m) · 80% at 6,050 ft (1,844 m) · 75% at 7,750 ft (2,362 m) · 70% at 9,540 ft (2,908 m) · 60% at 13,470 ft (4,106 m) · 50% at 17,970 ft (5,477 m). Above 36,089 ft the troposphere formula no longer applies.
How it is calculated
- Air pressure at the elevation from the U.S. Standard Atmosphere, 1976: P = 101.325 kPa × (1 − 2.25577 × 10⁻⁵ × h)5.25588, with h in meters.
- Oxygen per breath compared with sea level = P ÷ 101.325 kPa. The share of oxygen in dry air, 20.9476%, does not change with elevation in the lower atmosphere.
- Effective oxygen = 20.9476% × P ÷ 101.325 kPa: the oxygen percentage that would deliver the same oxygen per breath at sea level.
- Oxygen partial pressure = 0.209476 × P, shown in mmHg (1 kPa = 7.50062 mmHg). This is for dry outside air; air in the lungs is also diluted by water vapor.
Check: at 10,000 ft this gives 69%, matching the CDC Yellow Book's 69% of sea-level inspired oxygen pressure at about 10,000 ft.
Related tools
Frequently asked questions
Is there less oxygen at high altitude?
The air is still about 20.9% oxygen, the same as at sea level. What drops is air pressure, so each breath takes in fewer oxygen molecules. That lower partial pressure of oxygen is what the body notices.
How much oxygen is there at 10,000 feet?
In the standard atmosphere a breath at 10,000 ft holds about 69% of the oxygen it would at sea level. The CDC Yellow Book gives the same figure: at about 10,000 ft the inspired oxygen pressure is 69% of the sea-level value.
How much less oxygen is there in Denver?
Downtown Denver is 5,276 ft (USGS). In the standard atmosphere a breath there holds about 82% of the sea-level amount, about 18% less.
What does "effective oxygen" mean?
It is the oxygen percentage that would give the same oxygen per breath at sea level. At 10,000 ft it is about 14.4%, compared with 20.9% at sea level.
At what elevation does altitude sickness start?
The CDC says any unacclimatized traveler going to a sleeping altitude of 8,000 ft (2,450 m) or higher is at risk of altitude illness, and that the risk sometimes applies lower. At 8,000 ft a breath holds about 74% of the sea-level oxygen.
Does weather change the oxygen level?
A little. The calculator uses standard-atmosphere pressure. Low-pressure weather lowers the oxygen per breath slightly; high pressure raises it. Cold air at the same pressure does not change the percentage.
Sources
- U.S. Standard Atmosphere, 1976 (NOAA, NASA, USAF) — air pressure by elevation and the 20.9476% oxygen fraction of dry air
- CDC Yellow Book: High-Altitude Travel and Altitude Illness — inspired oxygen at 10,000 ft (69% of sea level) and the 8,000 ft sleeping-altitude risk threshold
- USGS Elevation Point Query Service — city elevations in the table and your elevation when you use your location
- Published summit elevations (named on each mountain page) — mountain elevations in the table
- Terrain Tiles on AWS (Mapzen) — La Paz elevation
How each number is produced: methodology and data sources.