Pressure Altitude Calculator
Our meteorology & atmospheric science calculator computes pressure altitude accurately. Enter measurements for results with formulas and error analysis.
Calculator
Adjust values & calculateFormula
Where PA is pressure altitude in meters and P is station pressure in hPa. Density altitude adds temperature correction: DA = PA + 120*(T - ISA_temp). ISA temperature at altitude: T_ISA = 15 - 0.0065*PA.
Last reviewed: December 2025
Worked Examples
Example 1: Sea Level Airport
Example 2: Mountain Airport
Background & Theory
The Pressure Altitude Calculator applies the following established principles and formulas. Earth science calculators draw on a wide range of measurement scales and physical principles that quantify natural phenomena across geological, atmospheric, and hydrological systems. Earthquake magnitude is most precisely described by the Moment Magnitude Scale (Mw), which replaced the original Richter scale for larger events. Mw is calculated as Mw = (2/3) log10(M0) − 10.7, where M0 is the seismic moment in dyne-centimeters. The Richter scale, while still referenced colloquially, is a local magnitude (ML) measurement derived from peak seismograph amplitude at a standard 100 km distance. Wind intensity is classified using the Beaufort Scale, a 13-point empirical scale (0–12) relating wind speed in knots to observable sea and land effects, with Beaufort 12 corresponding to hurricane-force winds above 64 knots. Tropical cyclone intensity is further categorized by the Saffir-Simpson Hurricane Wind Scale, which assigns Categories 1 through 5 based on sustained wind speed, correlating with expected structural damage. Mineral hardness is quantified on the Mohs scale (1–10), comparing scratch resistance relative to reference minerals from talc (1) to diamond (10). Soil composition analysis measures the proportions of sand, silt, and clay by particle size, alongside organic matter content, bulk density, and porosity, which together determine engineering and agricultural suitability. Seismic wave velocity in rock varies by material: P-waves travel at approximately 5–7 km/s in granite and 1.5 km/s in water, while S-waves travel at roughly 60% of P-wave speeds. Atmospheric pressure decreases with altitude according to the barometric formula: P = P0 × exp(−Mgh / RT), where M is molar mass of air, g is gravitational acceleration, h is altitude, R is the universal gas constant, and T is temperature in Kelvin. Standard sea-level pressure is 101,325 Pa. Tidal calculations use harmonic analysis of gravitational forcing by the Moon and Sun, with the principal lunar semidiurnal tidal constituent (M2) having a period of approximately 12.42 hours.
History
The history behind the Pressure Altitude Calculator traces back through the following developments. The systematic study of Earth's structure and processes spans millennia, but the scientific foundations were laid in the seventeenth century. In 1669, Danish naturalist Nicolas Steno published his principles of stratigraphy, establishing the laws of superposition, original horizontality, and lateral continuity — foundational rules for reading rock layers that remain in use today. Scottish geologist James Hutton introduced the concept of uniformitarianism in 1788, proposing that geological processes observable in the present have operated throughout Earth's history at broadly consistent rates. This idea of deep time challenged prevailing biblical chronologies and set the stage for modern geology. Charles Lyell systematized these ideas in his landmark three-volume work Principles of Geology, published beginning in 1830, which directly influenced Charles Darwin's thinking on biological evolution during the voyage of the Beagle. The nineteenth century saw growing curiosity about continental shapes, but a coherent theory awaited Alfred Wegener, a German meteorologist who proposed continental drift in 1912, arguing that the continents had once formed a supercontinent he called Pangaea. His evidence included matching fossil records and geological formations across the Atlantic, but his mechanism was disputed for decades. The theory gained acceptance in the 1960s when seafloor spreading was confirmed through paleomagnetic studies, and plate tectonics emerged as the unifying framework of modern geoscience. The United States Geological Survey was established by Congress in 1879 to classify public lands and examine the geological structure, mineral resources, and products of the national domain. The twentieth century brought instrumental advances, including the global seismograph network deployed after World War II, initially to monitor nuclear tests, which dramatically improved earthquake detection and characterization. Satellite Earth observation began in earnest with the Landsat program launched in 1972, enabling continuous global monitoring of land use, glacier retreat, and vegetation patterns. Today, GPS networks, LIDAR scanning, and ocean-floor mapping provide centimeter-scale precision for tracking tectonic motion, sea level rise, and volcanic deformation in near real time.
Frequently Asked Questions
Formula
PA = 44330 * (1 - (P/1013.25)^0.1903)
Where PA is pressure altitude in meters and P is station pressure in hPa. Density altitude adds temperature correction: DA = PA + 120*(T - ISA_temp). ISA temperature at altitude: T_ISA = 15 - 0.0065*PA.
Worked Examples
Example 1: Sea Level Airport
Problem: Station pressure 1005 hPa, temperature 30 C, elevation 50 ft.
Solution: PA = 44330*(1-(1005/1013.25)^0.1903) PA = 68 m (223 ft) ISA at 68m = 14.9C, deviation = +15.1C DA = 68 + 120*15.1 = 1880 m (6168 ft)
Result: PA: 68 m | DA: 1880 m | Performance Impact
Example 2: Mountain Airport
Problem: Station pressure 850 hPa, temperature 25 C.
Solution: PA = 44330*(1-(850/1013.25)^0.1903) PA = 1457 m (4781 ft) ISA = 12.1C, dev = +12.9C DA = 1457+120*12.9 = 3005 m
Result: PA: 1457 m | DA: 3005 m | High
Frequently Asked Questions
What is pressure altitude and why is it important?
Pressure altitude is the altitude in the standard atmosphere at which the given pressure would be found. It equals 44330*(1-(P/1013.25)^0.1903) meters where P is the actual station pressure. Pressure altitude is fundamental in aviation because aircraft altimeters work by measuring pressure and converting it to altitude using the standard atmosphere model. It determines aircraft performance characteristics including takeoff distance rate of climb and service ceiling. When the altimeter setting is 29.92 inHg the indicated altitude equals pressure altitude.
How does pressure altitude differ from density altitude?
Pressure altitude only accounts for pressure while density altitude additionally corrects for non-standard temperature. Density altitude equals pressure altitude plus approximately 120 times the temperature deviation from ISA in Celsius. Density altitude is the altitude in the standard atmosphere with the same air density as the actual conditions. Aircraft performance charts typically reference density altitude because engine power and wing lift both depend on air density. On hot days density altitude can be thousands of feet above pressure altitude reducing aircraft performance.
How do pilots use pressure altitude?
Pilots use pressure altitude for multiple critical operations. During takeoff and landing they calculate pressure altitude to determine required runway length and climb performance. Above the transition altitude typically 18000 feet in the US all aircraft set altimeters to 29.92 inHg and fly at flight levels based on pressure altitude ensuring safe vertical separation. Pressure altitude determines oxygen requirements with supplemental oxygen required above 12500 feet pressure altitude for extended periods. Performance charts in pilot operating handbooks are indexed to pressure altitude and temperature.
How is pressure altitude related to altimeter settings?
The altimeter setting is the pressure at mean sea level that makes the altimeter read field elevation on the ground. When the altimeter is set to the current local setting it shows elevation not pressure altitude. Setting 29.92 inHg (1013.25 hPa) makes the altimeter display pressure altitude directly. The relationship between station pressure and altimeter setting involves correcting for elevation using the hypsometric equation. A one inHg change in altimeter setting corresponds to approximately 1000 feet of altitude change near sea level.
What factors cause pressure altitude to change?
Pressure altitude changes whenever the station pressure changes which occurs due to weather systems and diurnal pressure variations. Low pressure weather systems raise pressure altitude sometimes by several hundred feet while high pressure systems lower it. Temperature does not directly affect pressure altitude but changes density altitude. Elevation determines baseline station pressure with higher elevation airports having inherently higher pressure altitudes. Seasonal pressure patterns also affect average pressure altitude at a given location.
How does density altitude affect aircraft performance?
Higher density altitude degrades all aspects of aircraft performance because thinner air reduces both engine power output and aerodynamic lift. Takeoff distance increases significantly with density altitude requiring longer runways. Rate of climb decreases which is critical at airports surrounded by terrain. True airspeed increases relative to indicated airspeed requiring adjustment for navigation. Propeller efficiency decreases in thinner air. As a rule of thumb takeoff distance increases about 10 percent for every 1000 feet of density altitude above sea level.
References
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy