That's a great question, and honestly, it's one a lot of people don't think about until they hear that awful cracking sound! There isn't a single universal number, as the weight limit depends heavily on the bin's material, construction, and size. However, I can give you a solid real-world breakdown.
For a standard 32-gallon plastic curbside bin (the kind most homes use), you're generally looking at a safe working limit of about 40-50 pounds (18-23 kg). Exceeding this, especially with dense, compacted trash or a single heavy item, can cause the bottom to sag, crack, or completely give out. These bins are designed for lightweight household waste, not construction debris or bricks.
Heavy-duty 95-gallon rollout carts used by many municipalities are sturdier. They can often handle 200-250 pounds (90-113 kg) when the weight is distributed evenly. Commercial dumpsters (like 2-4 cubic yard front-load models) are built for much more, typically supporting 800 to 1,500+ pounds, but their steel bottoms can still fail from extreme overloads or improper loading (e.g., dropping heavy debris from a height).
Key factors that lead to failure are: Material (thin plastic vs. thick polyethylene vs. steel), Construction (molded vs. welded seams, ribbed bottoms), Age and Weather (UV exposure makes plastic brittle), and Load Distribution. A single bag of concrete mix concentrated in one spot is far more damaging than evenly distributed bagged leaves.
To avoid a messy cleanup, don't overfill bins, break down boxes, and never toss in extremely heavy individual items. If you regularly have heavy waste, consider a commercial-grade bin or more frequent pickups. Listen to your bin—if it's straining or sagging, it's time to lighten the load.