That's a great and practical question! It's one of those things you don't think about until you hear that awful cracking sound or find a mess on your patio. There isn't a single universal number, as it depends heavily on the can's material, construction, and age. However, a typical 32-gallon plastic outdoor trash can, which is very common, is generally designed to hold about 40-50 pounds of bagged household waste safely.
The "bottom giving out" usually happens from a combination of weight and pressure points. Overfilling the can with heavy, compacted debris (like wet leaves, construction waste, or dense garden clippings) can easily push the load past 80-100 pounds. At that point, the plastic flexes and weakens, especially in extreme heat or cold. The bottom often fails along the seams or where the wheels are attached.
Metal cans, like galvanized steel, have a much higher structural weight capacity (often 200+ lbs) but can rust through from the inside out if liners aren't used. The real weak point for any can is frequently the wheels or the axle mounts.
To prevent a blowout, avoid compacting trash with force, don't overload beyond the rim, and use a liner bag. For heavy waste, consider a contractor-grade bin or make multiple trips. Investing in a can with a thick, ribbed bottom and reinforced base is worth it for longevity. Listen to your can—if the sides are bulging, it's time to lighten the load!