That's an excellent question! Finding the right size bag liner can be frustrating, but it's simpler than you might think. The key is to grab a tape measure and get two specific dimensions from your empty trash can.
First, measure the circumference (the distance around the top opening). If you don't have a flexible tape, you can wrap a string around the top, mark it, and then measure the string's length. This is your most important measurement.
Second, measure the height (or depth) of the can from the bottom to just below the rim.
Now, grab a box of potential liners. Look at the manufacturer's specifications on the side. They should list the "compressed circumference" or "top width" and the bag's height. Your can's circumference should be equal to or slightly *larger* than the bag's listed compressed circumference. This ensures a snug fit that won't slip down. For the height, your bag should be tall enough to fold over the rim, with a little extra to secure it.
A great pro-tip: If your can has an unusual shape, look for "drawstring" or "cinch" bags, as they often provide a more secure fit. Remember, a well-fitted liner prevents messes and makes taking the trash out so much easier