That's an excellent and very practical question! For a standard 50-gallon trash bin, the most common and recommended liner bag size is actually 55 to 60 gallons.
Here’s the simple reasoning: a bag labeled for the exact bin capacity, like a "50-gallon bag," is designed to fit the bin's interior dimensions when the bin is *empty*. Once you start filling it, the bag needs extra material to gather at the top for tying. A slightly larger bag (55-60 gallons) provides that crucial overhang, making it easier to secure without tearing and preventing the bag from slipping down into the bin.
For typical kitchen or general waste, a 56-gallon tall kitchen bag is often a perfect fit for a 50-gallon bin. If you're dealing with lighter but bulkier items like recycling or packaging, a 60-gallon bag offers even more flexibility.
Pro Tip: Always check the bag's dimensions (width and length) against your bin's measurements. The bag should be several inches taller and wider than your bin's interior. A bag that's too small will be prone to rips and slips, while one excessively large is wasteful and cumbersome. For heavy, wet kitchen waste, consider bags with a higher micron thickness for extra strength.