acalculator

What's the pressure altitude?

Type the field elevation and the altimeter setting, or a station pressure. The pressure altitude calculator gives the pressure altitude from the standard-atmosphere formula, the pilot's rule of thumb, the station pressure and the standard temperature at that altitude.

Your numbers

Units
From
Pressure altitude
5,187 ft

The pressure altitude is 5,187 ft.

Rule of thumb
5,200 ft
Altimeter correction
187 ft
Station pressure (hPa)
837.1
Station pressure (inHg)
24.72
ISA temperature (°C)
4.7

Pressure altitude: 5,187 ft. The pressure altitude is 5,187 ft.

How to calculate

Pressure altitude calculator for pilots: the pressure altitude from the field elevation and altimeter setting, or from the station pressure, with the 1,000 ft per inch rule of thumb and the station pressure.

Example with the default inputs (From Altimeter setting, Field elevation 5,000 ft, Altimeter setting 29.72 inHg): The pressure altitude is 5,187 ft.

Method: h(p) = 145,366.45 × (1 − (p ÷ 1,013.25)^0.190284) ft, p in hPa. From a station pressure: PA = h(p). From an altimeter setting A: PA = elevation + h(A); station pressure = 1,013.25 × (1 − PA ÷ 145,366.45)^(1 ÷ 0.190284). Rule of thumb: elevation + 1,000 × (29.92 − A in inHg).

  • The standard atmosphere: 1,013.25 hPa (29.92 inHg) and 15 °C at sea level, cooling 1.9812 °C per 1,000 ft.
  • 1 inHg = 33.8639 hPa (mercury at 0 °C under standard gravity).

Machine-readable copies: Markdown, JSON.

Worked examples

Each example is checked against the calculator on every build.

  1. From Station pressure, Station pressure 29.92 inHg gives Pressure altitude 0 ft, ISA temperature (°C) 15.Source: Wikipedia, Pressure altitude (h = 145,366.45 × [1 − (station pressure in mb ÷ 1,013.25)^0.190284] ft; rule of thumb PA = elevation + 1,000 × (29.92 − altimeter setting)), https://en.wikipedia.org/wiki/Pressure_altitude (retrieved 2026-10-05)
  2. From Station pressure, Station pressure 24.89 inHg gives Pressure altitude 5,000 ft.Source: Wikipedia, Pressure altitude (h = 145,366.45 × [1 − (station pressure in mb ÷ 1,013.25)^0.190284] ft; rule of thumb PA = elevation + 1,000 × (29.92 − altimeter setting)), https://en.wikipedia.org/wiki/Pressure_altitude (retrieved 2026-10-05)
  3. From Altimeter setting, Field elevation 5,000 ft, Altimeter setting 29.72 inHg gives Pressure altitude 5,187 ft, Rule of thumb 5,200 ft.Source: Wikipedia, Pressure altitude (h = 145,366.45 × [1 − (station pressure in mb ÷ 1,013.25)^0.190284] ft; rule of thumb PA = elevation + 1,000 × (29.92 − altimeter setting)), https://en.wikipedia.org/wiki/Pressure_altitude (retrieved 2026-10-05)

How it works

The standard-atmosphere height of a pressure p in hPa (millibars) is

  • h(p) = 145,366.45 × (1 − (p ÷ 1,013.25)^0.190284) feet.

From a station pressure: pressure altitude PA = h(station pressure).

From an altimeter setting A: an altimeter set to A reads the field elevation on the ground, so the station pressure is the pressure whose height is elevation + h(A). That gives

  • PA = elevation (ft) + h(A), and the altimeter correction = h(A).
  • Station pressure = 1,013.25 × (1 − PA ÷ 145,366.45)^(1 ÷ 0.190284) hPa.
  • Rule of thumb = elevation + 1,000 × (29.92 − A in inHg), computed exactly from the typed values.

ISA temperature = 15 − 1.9812 × PA ÷ 1,000 °C (6.5 °C per km).

Unit sizes: 1 ft = 0.3048 m; 1 hPa = 1 mbar = 100 Pa; 1 inHg = 13.5951 × 9.80665 × 25.4 Pa = 3,386.389 Pa.

Rules

  • Field elevation from −1,500 ft to 30,000 ft; altimeter setting from 800 to 1,100 hPa; station pressure from 100 to 1,100 hPa.
  • A pressure altitude at or above 145,366.45 ft has no answer.

Output format

Pressure altitude, the rule of thumb and the correction in feet (US) or metres (Metric) to whole units; station pressure in hPa to 1 decimal and in inHg to 2 decimals; ISA temperature in °C to 1 decimal. The formula uses floats (powers); the rule of thumb is exact until it is rounded once.

Worked examples by hand

Standard pressure. p = 1,013.25 hPa: h = 145,366.45 × (1 − 1) = 0 ft, ISA 15 °C.

A station pressure. p = 843 hPa: (843 ÷ 1,013.25)^0.190284 = 0.965602, so h = 145,366.45 × 0.034398 = 5,000.2 ft.

An altimeter setting. A 5,000 ft field, 29.72 inHg = 1,006.43 hPa: h(A) = 186.56 ft, so PA = 5,186.56 ft. The rule of thumb gives 5,000 + 1,000 × 0.20 = 5,200 ft.

Other questions people ask

How do you calculate pressure altitude?

Add the field elevation to the altitude correction for the altimeter setting. The quick rule is PA = elevation + 1,000 × (29.92 − altimeter setting). At a 5,000 ft field with 29.72 inHg that is 5,000 + 200 = 5,200 ft; the exact formula gives 5,187 ft.

What is pressure altitude?

It is the altitude your altimeter shows when set to the standard 29.92 inHg (1,013.25 hPa): the height in the standard atmosphere at which the pressure equals the pressure where you are.

What is the pressure altitude formula?

h = 145,366.45 × [1 − (p ÷ 1,013.25)^0.190284] feet, where p is the station pressure in hectopascals (millibars). This is the formula the US National Weather Service uses.

Why does the rule of thumb differ from the formula?

The rule assumes 1,000 ft per inch of mercury everywhere. Near sea level the formula gives about 937 ft for the first inch, so the rule overstates the correction a little; the error grows as the setting moves away from 29.92.

Is pressure altitude the same as density altitude?

No. Pressure altitude corrects only for pressure. Density altitude also corrects for temperature (and humidity), and it is the one that sets aircraft performance.

What is the difference between altimeter setting and station pressure?

Station pressure is the actual pressure at the field. The altimeter setting is that pressure reduced to sea level, so an altimeter set to it reads the field elevation on the ground.