With respect to aircraft, a ceiling is the maximum density altitude an aircraft can reach under a set of conditions.

The word ceiling can also refer to the height of the lowest obscuring cloud layer above the ground.

The service ceiling attempts to capture the maximum usable altitude of an aircraft. Specifically, it is the density altitude at which flying in a clean configuration, at the best rate of climb airspeed for that altitude and with all engines operating and producing maximum continuous power, will produce a given rate of climb (usually 100 feet per minute climb or 30 meters per minute, and 500 feet per minute climb for Jet Airplanes) Margin to stall at service ceiling is 1.5g.^{[citation needed]}

The one engine inoperative (OEI) service ceiling of a twin-engine, fixed-wing aircraft is the density altitude at which flying in a clean configuration, at the best rate of climb airspeed for that altitude with one engine producing maximum continuous power and the other engine shut down and feathered, will produce a given rate of climb (usually 50 feet per minute).^{[citation needed]}