Calculate atmospheric pressure at any altitude using the barometric formula. Essential for aviation, weather prediction, and high-altitude physics.
Accurate to ~11km
Standard: 1013.25 hPa
Atmospheric pressure decreases exponentially with altitude. As you climb, there is less air mass above you pressing down. The barometric formula provides a mathematical model for pressure variation, assumed a constant temperature lapse rate in the troposphere.
This calculator uses the standard lapse rate model, assuming temperature decreases 6.5 K per kilometer. This is accurate up to about 11 km altitude in the troposphere. Commercial aircraft cruise around 10,000-12,000 meters.
Key Fact: Pressure drops by ~50% every 5.5 km (scale height). Mount Everest (8,849m) has only ~34% sea level pressure.
Less air mass above means less weight pressing down. Exponential decrease due to decreasing density with altitude.
Lower pressure → lower boiling point. Water boils at ~68°C at 3000m vs. 100°C at sea level.
10,000m altitude pressure (25% sea level) is lethal without oxygen. Pressurization maintains ~8,000m equivalent inside.
~5.5 km in troposphere. Pressure halves every scale height. Used for quick exponential estimation.
Accurate to ~11 km (troposphere). Stratosphere and higher have different conditions and lapse rates.
Altimeter uses pressure difference. GPS is most accurate but altimeter is standard in aviation.
Lower pressure → lower oxygen partial pressure. Less O₂ available even though composition is ~21%.
Reduced oxygen availability. Body can acclimatize in days/weeks. Sea level → 2500m+ quickly causes issues.
Air Density
Calculate density at altitude
Boiling Point
Temperature effects on altitude
Dew Point
Condensation temperature
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