What is a #4 plastic?

What Is #4 Plastic and Where Do You Find It?

When you're sorting your recycling, you might have noticed a tiny number inside the recycling symbol on plastic items. That number tells you what type of plastic it is—and #4 plastic is known as LDPE, or Low-Density Polyethylene.

LDPE is a flexible, lightweight plastic commonly used in everyday household items. You’ve likely handled it without even realizing—think of the soft crinkle of grocery bags, the clingy feel of shrink wrap, or the thin film around a loaf of bread. It’s also found in less obvious places, like margarine tubs, some squeeze bottles, and even components in clothing and carpet fibers.

One of the benefits of LDPE is its durability and resistance to moisture, which makes it ideal for packaging. However, while it’s technically recyclable, not all curbside programs accept it due to processing limitations. Many grocery stores offer drop-off bins specifically for plastic bags and wraps—often made from LDPE—so they can be properly recycled.

Because it doesn’t break down easily in nature, reducing single-use plastics and reusing LDPE items when possible is a smarter choice. A reusable shopping tote, for instance, beats grabbing a new plastic bag—even if it’s made from #4 plastic.

Understanding what #4 plastic is and where it shows up helps you make more informed decisions. It’s not just about tossing things in the right bin; it’s about recognizing the materials we use every day and thinking critically about how we use—and reuse—them.