Free aviation & aerospace calculators

Cabin Altitude Calculator

What your body really feels at cruise.

Pressurized aircraft hold a maximum pressure differential (ΔP) between inside and outside. Pick an aircraft and cruise altitude to see the cabin altitude your body actually experiences, and the blood oxygen (SpO₂) that comes with it.

Cabin Altitude Calculator

Pressurized aircraft don't hold the cabin at sea level — they maintain a maximum pressure differential (ΔP) between inside and outside. Pick an aircraft and cruise altitude to see the cabin altitude your body actually experiences, and the blood oxygen (SpO₂) that comes with it.

Educational estimates only — not for flight planning, dispatch, or weight-and-balance. Always fly the numbers in your POH and current official weather.

ft
Max Differential
8.65 psi
Cabin Blood O₂ (SpO₂)
95%
Cabin Altitude
7,000 ft
Cabin altitude Unpressurized (cabin = altitude) ▭ Shaded gap = what pressurization saves you

Frequently asked questions

Why are airliner cabins pressurized to about 8,000 feet?

The fuselage can only hold a limited pressure difference (ΔP). At cruise the system maintains that maximum differential, which works out to a cabin altitude near 8,000 ft for most airliners. Composite jets like the 787 and A350 tolerate a higher ΔP and target ~6,000 ft.

What is cabin altitude?

Cabin altitude is the effective altitude your body experiences inside a pressurized aircraft — based on the cabin pressure the system holds, not the altitude you're flying at. A jet at 38,000 ft typically holds a cabin near 6,000–8,000 ft.