The weight of an airplane depends on its size, type and configuration. The FAA classifies aircraft into six weight classes, the smallest being for airplanes under 12,500 pounds and the largest being for airplanes over 300,000 pounds.

The FlyNano, an ultralight aircraft, is the lightest plane certified for flight. It has an empty weight of 70 kilograms, with a maximum takeoff weight of 200 kilograms. In contrast, the AN-225 cargo aircraft is the largest plane in operation. It has an empty weight of 285 metric tons and a maximum takeoff weight of 640 metric tons. The empty weight of an aircraft is determined by calculating its weight free of fuel, cargo and passengers.