That's an excellent and very practical question! For a standard 50-gallon outdoor trash bin, the best liner size is actually a bag labeled for 55 to 60 gallons.
Here’s why this "oversizing" is the natural choice for most of us:
A "50-gallon" bag is designed to hold 50 gallons of content when filled completely. If you try to fit it into a 50-gallon can, it will be stretched taut against the interior with no slack. This makes it incredibly difficult to secure over the rim, and the slightest overfill or sharp object can cause a tear or rip.
Using a 55 or 60-gallon bag provides that crucial extra material. It allows you to easily drape the bag over the entire rim of the bin, creating a neat cuff that you can tuck or secure. This extra slack also means the bag can accommodate a full load without being under extreme stress at the seams. It makes tying the bag closed much easier and helps prevent the liner from slipping down into the can when you toss in heavy debris.
When shopping, look for keywords like "heavy-duty," "contractor grade," or "outdoor." These bags are thicker and more resistant to tears, punctures, and weather elements—essential for outdoor use. So, while it might seem counterintuitive, reaching for a liner a size up from your bin's capacity is the simple secret to a cleaner, more hassle-free trash routine.