Work out cabin pressure differential instantly with clear inputs, formula shown and shareable results.
Cabin differential is the cabin pressure minus the outside pressure, both taken from the standard atmosphere at their respective altitudes. Airframes are certified to a maximum differential, and that limit — not engine or system capacity — is what sets the cabin altitude achievable at a given cruise level.
Cabin differential
dP = P(cabin altitude) - P(cruise altitude), P(h) = 14.696 x (1 - 6.87535e-6 h)^5.2559 psi
Aviation results are planning estimates only. Always verify take-off, landing, fuel, weight and balance figures against the certified Aircraft Flight Manual, current performance charts and applicable aviation regulations before flight.
The structure would need to withstand around 14 psi differential at high cruise levels, which means a much heavier fuselage. Cabin altitudes of 6,000-8,000 ft are the weight compromise.
Relief valves open to protect the structure, so cabin altitude rises. Repeated over-pressure cycles are a structural fatigue concern and must be recorded.