Uses the International Standard Atmosphere model (layered) for typical altitudes. Local weather and temperature can shift real-world pressure values.
If you have ever noticed that your ears pop when driving through the mountains or flying in an airplane, you have already felt the effects of changing air pressure. This air pressure at altitude calculator estimates atmospheric pressure at a given elevation so you can plan hikes, analyze weather conditions, prepare for flight training, or simply satisfy your curiosity.
What is air pressure, and why does it drop with altitude?
Air pressure is the force exerted by the weight of air above a given point. At sea level, there is a tall column of air above you, so the pressure is higher. As you go up in altitude, there is less air above you, and pressure decreases.
At standard sea level conditions, pressure is about 1013.25 hPa (or 101,325 Pa). By around 5,000 meters, pressure is nearly half that value. This is one reason high-altitude environments can feel physically demanding.
How to use this calculator
- Enter your altitude value.
- Select meters or feet.
- Set sea-level pressure (default is standard atmosphere: 1013.25 hPa).
- Select your desired output unit (hPa, Pa, kPa, atm, psi, mmHg, or inHg).
- Click Calculate Pressure.
The result also shows pressure as a percentage of sea-level pressure, which is useful for quick comparisons across locations.
Formula and model assumptions
This calculator uses a layered International Standard Atmosphere (ISA) approach. In the troposphere (up to about 11 km), a common form of the barometric equation is:
P = P0 × (T / T0)^(-g / (L×R))
Where:
- P = pressure at altitude
- P0 = pressure at the base layer (or sea level)
- T, T0 = temperature at altitude and base
- g = gravitational acceleration
- L = temperature lapse rate
- R = specific gas constant for dry air
In isothermal layers (where temperature is nearly constant), an exponential form is used. This gives a practical and reliable estimate across common aviation, hiking, and mountain altitudes.
Quick reference: typical pressure by altitude
| Altitude | Approx Pressure (hPa) | Pressure vs Sea Level |
|---|---|---|
| 0 m (0 ft) | 1013.25 | 100% |
| 500 m (1,640 ft) | 954.6 | 94% |
| 1,000 m (3,281 ft) | 898.8 | 89% |
| 2,000 m (6,562 ft) | 794.9 | 78% |
| 3,000 m (9,843 ft) | 701.1 | 69% |
| 5,000 m (16,404 ft) | 540.5 | 53% |
| 8,000 m (26,247 ft) | 356.0 | 35% |
| 10,000 m (32,808 ft) | 264.4 | 26% |
Practical uses
1) Hiking and mountaineering
Lower pressure means thinner air and reduced oxygen availability. While pressure itself does not determine blood oxygen directly, it strongly influences how much oxygen your lungs can absorb.
2) Aviation and drone flight
Pilots use pressure-altitude concepts for performance calculations. Engine output, lift, and climb rate are all sensitive to air density and pressure conditions.
3) Weather interpretation
If local sea-level pressure is unusually low or high (storm systems, high-pressure ridges), your calculated pressure can shift accordingly. That is why this tool lets you customize sea-level pressure rather than forcing one fixed value.
FAQ
Is this the same as a weather station reading?
Not exactly. This is a model-based estimate. Real readings depend on local temperature profiles, humidity, and weather systems.
Can I use feet instead of meters?
Yes. Enter your altitude in feet and choose Feet (ft). The calculator converts automatically.
What altitude range works best?
The layered model is strongest across common Earth altitudes, especially from below sea level to commercial-flight ranges. For extremely high altitudes, the tool still provides an approximation but labels it as extended.
Bottom line
This air pressure at altitude calculator gives you a fast, practical way to estimate atmospheric pressure at elevation. Whether you are preparing for a mountain trek, doing school science work, or comparing city elevations, the tool can save time and improve accuracy.