What the standard-datum sky says your altitude is.
Pressure altitude is your height above the standard 29.92 inHg pressure level — the altitude your POH performance charts, flight levels, and density altitude all start from. Enter an altimeter setting and field elevation, or type any airport ID to autofill both from the live METAR, and get pressure altitude and density altitude in one shot.
Type an airport for live data, or enter the altimeter setting and elevation yourself. Add the outside air temperature to also get density altitude — the "PA + DA" combo.
Educational estimates only — not for flight planning or dispatch. Fly your POH numbers and official weather sources.
Pressure altitude is the altitude indicated when the altimeter is set to 29.92 inHg (1013.25 hPa) — your height above the standard datum plane rather than above sea level. It's the altitude aviation performance data is built on: POH takeoff and landing charts, true airspeed math, and all flight levels above the transition altitude use pressure altitude.
The formula every student pilot memorizes:
Pressure Altitude = Field Elevation + (29.92 − Altimeter Setting) × 1,000
Worked example 1: Denver (field elevation 5,434 ft) with an altimeter setting of 29.62: PA = 5,434 + (29.92 − 29.62) × 1,000 = 5,434 + 300 = 5,734 ft. Low pressure raises pressure altitude.
Worked example 2: The same field on a high-pressure day, altimeter 30.22: PA = 5,434 + (29.92 − 30.22) × 1,000 = 5,434 − 300 = 5,134 ft. When the setting is above 29.92, the correction is negative — pressure altitude can even be below sea level.
Add temperature and you get density altitude: DA = PA + 120 × (OAT − ISA temperature). That's why this page's calculator asks for OAT — it's the classic "PA/DA" one-two used on every performance chart.
| Altitude | Reference | How you get it | When it matters |
|---|---|---|---|
| Indicated | Local altimeter setting | Read the altimeter | Everyday flying below 18,000 ft |
| Pressure | 29.92 inHg standard datum | Set 29.92, or this formula | Performance charts, flight levels |
| Density | PA corrected for temperature | DA calculator | Aircraft performance — the one that bites |
| True | Mean sea level | Indicated corrected for temp/pressure | Terrain & obstacle clearance |
| Absolute | Ground below you | Radar altimeter | AGL minimums, pattern height |
Full explainer with examples: the 6 types of altitude every pilot should know.
| Altimeter (inHg) | ≈ hPa | Correction to field elevation |
|---|---|---|
| 28.92 | 979 | +1,000 ft |
| 29.42 | 996 | +500 ft |
| 29.92 | 1013 | 0 ft (standard day) |
| 30.42 | 1030 | −500 ft |
| 30.92 | 1047 | −1,000 ft |
Rule of thumb: every 0.10 inHg away from 29.92 moves pressure altitude 100 ft — lower pressure, higher PA.
29.92 inHg (1013.25 hPa) is the sea-level pressure of the International Standard Atmosphere — the agreed reference so that performance data, instruments, and flight levels mean the same thing everywhere. Above the transition altitude (18,000 ft in the US) everyone sets 29.92 so traffic separation uses the same datum.
Yes. On a high-pressure day (altimeter above 29.92) the correction is negative, and at a low-elevation field pressure altitude can compute below zero — e.g., a sea-level airport with a 30.42 setting has a pressure altitude of about −500 ft. Your aircraft simply performs a little better than book sea-level numbers.
Only on a standard day. When the altimeter setting is exactly 29.92, pressure altitude equals field elevation. Any other setting moves it: about 100 ft per 0.10 inHg, higher PA when pressure is lower.
Set the altimeter to 29.92 and read it — that is pressure altitude by definition. Then reset the local altimeter setting. Alternatively apply the rule of thumb: add or subtract 100 ft per 0.10 inHg the setting differs from 29.92.
Pressure altitude only accounts for pressure; density altitude adds temperature. DA = PA + 120 × (OAT − ISA temp). On a hot day the density altitude is far above the pressure altitude — and density altitude is what actually drives takeoff distance, climb rate, and engine power.
DensityAlt is a set of free, no-signup aviation calculators. Explore the rest: