While the weight must be checked, the center of gravity location is of equal importance. The distribution of the passengers in the aircraft is also taken into consideration. Aircraft are not weighed prior to each flight, but the basic empty weight must be known and checked periodically per regulation.

In 2026, commercial aircraft are not physically weighed on a giant scale before every takeoff; instead, their weight is calculated mathematically using a "Weight and Balance" manifest. Dispatchers and pilots calculate the "Zero Fuel Weight" by adding the known empty weight of the plane to the specific weight of the cargo and a standardized average weight for passengers and their carry-on bags. In the U.S., the FAA sets these average weights (e.g., 190 lbs for an adult in summer). Once the specific fuel load is added, the "Takeoff Weight" is determined. However, for smaller commuter planes or in certain international jurisdictions (like New Zealand), airlines may occasionally perform "weigh-in" periods where passengers and bags are physically weighed to ensure their "standard averages" remain accurate for safety. Furthermore, modern aircraft like the Boeing 787 and Airbus A350 feature Onboard Weight and Balance Systems (OBWBS)—sensors in the landing gear that can measure the physical pressure exerted by the plane's weight. While these are used as a "safety check," the pilot's final performance calculations for thrust and flap settings are still primarily based on the digital manifest.