Zero Fuel Weight (ZFW)

Maximum Zero Fuel Weight (MZFW) is the greatest weight of the aircraft and its payload before any usable fuel is added. It exists because fuel in the wings helps relieve structural bending loads, so there's a limit on how much non-fuel weight the structure can carry — often the true constraint on payload on shorter legs.

Why it matters: maximum zero fuel weight is a structural limit protecting the wing root — everything loaded in the fuselage that is not fuel bends the wing upward at its attachment, and MZFW caps that load. It is the limit that bites on cargo-heavy or cabin-heavy operations.

Practically, an operator can hit MZFW before MTOW: the aircraft cannot legally take more cabin or hold load even though total weight allows more fuel. Freight and combi operators live with this limit daily, and buyers with dense-load missions should check MZFW margins, not just MTOW.