Altitude to Oxygen Chart
How much oxygen is available at a given altitude, in metres and feet. Use it to see what an altitude setting on a simulated-altitude system corresponds to.
The air is about 20.9% oxygen at every altitude. What falls as you climb is the air pressure, so each breath holds less oxygen. A simulated-altitude system reproduces that at normal pressure by lowering the oxygen percentage instead. The "equivalent oxygen" column is the percentage a sea-level system has to hold to match each altitude.
| Altitude (m) | Altitude (ft) | Equivalent oxygen at sea-level pressure | Oxygen available vs sea level | Reference |
|---|---|---|---|---|
| 0 m | 0 ft | 20.9% | 100% | Sea level |
| 250 m | 820 ft | 20.3% | 97% | |
| 500 m | 1,640 ft | 19.7% | 94% | |
| 750 m | 2,460 ft | 19.1% | 91% | |
| 1,000 m | 3,280 ft | 18.5% | 89% | |
| 1,250 m | 4,100 ft | 18.0% | 86% | |
| 1,500 m | 4,920 ft | 17.4% | 83% | |
| 1,750 m | 5,740 ft | 16.9% | 81% | |
| 2,000 m | 6,560 ft | 16.4% | 78% | Lower end of the range many athletic sleep protocols use |
| 2,250 m | 7,380 ft | 15.9% | 76% | |
| 2,500 m | 8,200 ft | 15.4% | 74% | Upper end of that range |
| 2,750 m | 9,020 ft | 14.9% | 71% | |
| 3,000 m | 9,840 ft | 14.5% | 69% | |
| 3,250 m | 10,660 ft | 14.0% | 67% | |
| 3,500 m | 11,480 ft | 13.6% | 65% | |
| 3,750 m | 12,300 ft | 13.1% | 63% | |
| 4,000 m | 13,120 ft | 12.7% | 61% | |
| 4,250 m | 13,940 ft | 12.3% | 59% | |
| 4,500 m | 14,760 ft | 11.9% | 57% | |
| 4,750 m | 15,580 ft | 11.5% | 55% | |
| 5,000 m | 16,400 ft | 11.1% | 53% | |
| 5,500 m | 18,040 ft | 10.4% | 50% | About half of sea-level oxygen availability |
| 6,000 m | 19,690 ft | 9.7% | 47% | |
| 7,000 m | 22,970 ft | 8.5% | 41% | |
| 8,000 m | 26,250 ft | 7.3% | 35% | |
| 8,849 m | 29,030 ft | 6.5% | 31% | Summit of Everest |
Calculated from the ICAO standard atmosphere: pressure ratio = (1 − 2.25577 × 10⁻⁵ × altitude in metres)5.25588, multiplied by 20.9%. Real conditions vary a little with weather and latitude, and feet are rounded to the nearest 10.
Using the chart with an altitude system
Box Altitude systems are set in altitude, not in oxygen percentage: you choose a target altitude in the app, the sensor measures the oxygen level in the tent or room, and the generator works to hold the matching level. The chart shows what each setting means. The table runs to the summit of Everest for reference; the settings available on a system depend on its generator and stop well below that.
Many athletic sleep protocols use altitudes of around 2,000 to 2,500 metres, but the appropriate altitude and schedule vary between individuals. Begin conservatively and increase gradually. People with medical conditions, or with any concern about reduced-oxygen exposure, should seek advice from a qualified healthcare professional before starting.
See the Sleep Cloud altitude tent, the Training Cloud and the Altitude Bedroom System, or read how long to sleep in an altitude tent.
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