Airlines set weight limits for luggage for safety reasons. An accurate calculation of the fuel necessary to fly an airplane depends upon an accurate assessment of the weight of the plane and its contents, including passengers and luggage, states USA Today. Restricting luggage weight enables more accurate weight assessments.
The fact that airlines charge fees for many services and amenities that were formerly free, such as checked bags and in-flight meals, may lead to the assumption that weight limits are yet another facet of perceived airline money-gouging. In fact, the reasoning behind the weight limit fees is directly related to logistical considerations, such as fuel allowance and spacing. Another issue is that baggage handlers must be able to move luggage with ease.
The weight limit for checked baggage on domestic flights is commonly set at 50 pounds. Any single piece of luggage weighing more than 50 pounds is subject to a fee. Some airlines increase the fee for overweight baggage that exceeds a secondary threshold, often 70 pounds. Some airlines refuse to carry baggage weighing more than 100 pounds, even for a fee. Most airlines do not specifically restrict the weight of carry-on bags, though they do recommend that heavier items are stored under the seat rather than in overhead bins for safety purposes.