Barometric Pressure-Altitude Calculator
Calculate atmospheric pressure at a given altitude using the barometric formula.
Assumptions used in this calculation
- Standard atmosphere model: Uses the International Standard Atmosphere's standard temperature lapse rate, actual local pressure varies with weather and temperature conditions.
About this calculator
Atmospheric pressure doesn't drop linearly with altitude, it falls off following an exponential-like curve because each layer of air is compressed by the weight of all the air above it, which itself thins out as you go up, so a simple proportional estimate of pressure loss with height gives noticeably wrong answers, especially at a few thousand metres. This calculator applies the barometric formula from the International Standard Atmosphere model, P = P₀ × (1 − 2.25577×10⁻⁵ × h)^5.25588, to compute pressure at a given altitude (valid up to 11 km, the troposphere) from sea-level pressure, and also shows that pressure as a percentage of the sea-level baseline. It's useful for pilots and hikers estimating pressure at altitude, understanding why high-altitude cooking requires longer times or altered recipes, or calibrating altimeters and pressure-based instruments that rely on this standard relationship between height and atmospheric pressure.
Worked example
1,500m altitude, standard sea-level pressure
Result: 84.6 kPa (83.5% of sea level)
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