Calculate atmospheric pressure at any altitude using the barometric formula. Essential for aviation, meteorology, and high-altitude activities.

Pressure: 89,874 Pa (898.7 hPa / 674.1 mmHg)

Note: Formula valid in the troposphere (up to ~11,000 m). Standard sea-level pressure is 101,325 Pa at 15°C.

What is Atmospheric Pressure at Altitude?

Atmospheric pressure is the force exerted by the weight of air above a given point [citation:5]. As altitude increases, there is less air mass above, so pressure decreases exponentially [citation:2][citation:5]. This relationship is described by the barometric formula [citation:1][citation:5]:

P = P₀ × e^{(-g·M·h)/(R·T)}

Where:

• P — pressure at altitude (Pa)
• P₀ — sea-level pressure (101,325 Pa at 15°C)
• g — gravitational acceleration (9.80665 m/s²)
• M — molar mass of air (0.0289644 kg/mol)
• h — altitude (m)
• R — universal gas constant (8.31446 J/(mol·K))
• T — absolute temperature (K)

This formula assumes an isothermal atmosphere — constant temperature with altitude — which is a reasonable approximation for the lower troposphere (up to ~11 km) [citation:2][citation:5]. In reality, temperature decreases with altitude at a lapse rate of ~6.5 K/km [citation:2][citation:6]. The calculator uses the isothermal version for simplicity, which gives accurate results for most practical purposes.

Atmospheric pressure is critical for:

• Aviation — altimeters measure altitude via pressure [citation:2][citation:10].
• Weather forecasting — pressure gradients drive wind and storms [citation:10].
• Climbing and mountaineering — knowing pressure helps assess altitude sickness risk.
• Boiling point calculations — water boils at lower temperatures at altitude [citation:2].

The scale height of the atmosphere is about 5.5 km — pressure drops by ~50% every 5.5 km [citation:2]. For example, at 8,849 m (Everest summit), pressure is only ~33% of sea level [citation:2][citation:11].

How to Use This Calculator

1. Enter Altitude: Input the height above sea level in meters (valid range: 0–11,000 m).
2. Enter Temperature: Input the air temperature in degrees Celsius at that altitude (valid: -50°C to 50°C).
3. Calculate: Click the “Calculate Pressure” button or press Enter on your keyboard.
4. Reset: Use the “Reset” button to restore default values (1,000 m, 15°C).
5. Interpretation: The result shows pressure in three units: Pascals (Pa), hectopascals (hPa/mb), and millimeters of mercury (mmHg). For example, at 1,000 m with 15°C, pressure is ~89,874 Pa (898.7 hPa) — about 11% lower than at sea level.