That's a great and surprisingly practical question! It gets to the heart of urban durability. For a standard, city-issued 32-gallon to 96-gallon wheeled trash bin (the typical curbside kind), the lid itself isn't rated to hold a significant, separate weight.
You generally shouldn't place heavy items on top of the closed lid. These lids are designed primarily to *cover* the contents, not to function as a shelf. Their "capacity" is more about withstanding their own weight when opened and closed repeatedly, plus environmental stress like wind and sun.
Most residential bin lids are made from rotationally molded polyethylene plastic. While tough, constant pressure from heavy objects (like a bag of potting soil, a toolbox, or someone sitting on it) can cause the hinge areas to crack or the lid to warp permanently, preventing a proper seal.
A safe, unofficial rule of thumb is to avoid placing anything heavier than 5-10 pounds (2-4.5 kg) directly on the lid for an extended period. The real weight capacity is for the *entire container*—the bin structure holds the trash weight, distributed evenly inside. Exceeding the bin's overall volume or putting extreme pressure on one point (like the lid) are the main causes of failure.
For commercial or heavy-duty bins, lids may be more robust, but the principle remains: the lid is a cover, not a load-bearing platform. Always check your municipality's guidelines for specific bin specifications and proper use to avoid damage fees.