Compute pressure altitude from barometric pressure.
由气压按国际标准大气反算海拔高度：h = 44330·(1 − (P/P₀)^0.1903)。
| Item | Formula | Source / Standard |
|---|---|---|
| Pressure altitude | h = 44330 (1 - (p / 1013.25)^(1 / 5.25588)) | ICAO standard atmosphere pressure altitude |
| QNH correction | pressure altitude corrected by QNH setting | ICAO altimetry setting procedures |
| Density altitude | DA = PA + 120 (OAT - ISA temperature) | ICAO density altitude practice |
Constants and standards used on this page with their authoritative sources, for verification and citation.
| Quantity | Value | Unit | Source |
|---|---|---|---|
| Equivalent height constant 44330 | T₀/L = 44330.8 | m | Derived from T₀ = 288.15 K and L = 0.0065 K/m |
| Exponent 0.1903 | R_d·L/g₀ = 0.190284 | dimensionless | ISO 2533 tropospheric hydrostatic integration |
| Standard sea-level pressure | 1013.25 (= 29.9213 inHg) | hPa | ISO 2533:1975 / ICAO Doc 7488 |
| Standard sea-level temperature T₀ | 288.15 | K | ISO 2533:1975 |
| Dry-air gas constant R_d | 287.05287 | J/(kg·K) | CIPM 2007 recommended value |
| Standard gravity g₀ | 9.80665 | m/s² | ISO 80000-3:2019 |
Note: pressure altitude is referenced to the standard atmosphere, not true elevation. Apply the local QNH correction, plus a temperature correction when the air column deviates from ISA.