What Is PBAT Plastic? Is It Compostable or Biodegradable?

Plant-based, biodegradable, compostable. They all sound like the same thing, and most packaging labels don't help. While compostable packaging sounds like it comes completely from the earth, a lot of people are shocked to find out that there's a good chance it's made with plastic.

That plastic is called PBAT, and once you understand PBAT, the rest of compostable packaging starts to make a lot more sense.

PBAT is a plastic that's designed to be composted. The full name is polybutylene adipate terephthalate, which is why everyone just says PBAT.

PBAT usually starts out the same way regular plastic does, from fossil fuels. The difference is how it ends. PBAT is built to break down into compost under the right conditions, which means it could be certified compostable.

If "plastic that composts" sounds like a contradiction, you're not alone.

A plastic can be compostable because where it comes from and where it ends up are two separate questions. "Plant-based" or "fossil-based" answers the first question: where did this material come from? "Compostable" answers the second question: where can it end up when you're done with it?

And those answers don't have to match. Take a regular poly mailer. It's made from fossil fuels, and it won't compost. You could make that exact same plastic from sugarcane instead, which would make it plant-based, but that doesn't automatically mean it can compost. PBAT is the flip side. It usually comes from fossil fuels, but it can end up as compost.

The European Environment Agency put it simply in 2020: plastic made from plants isn't necessarily compostable, and plastic that biodegrades can be made from fossil fuels.

Compostable mailers use PBAT because a mailer has to stretch and hold up in shipping, and PBAT adds that flexibility and toughness. It's usually blended with two other materials: PLA, which is a compostable plastic made from plant sugars, and starch. BASF, the company that introduced PBAT under the name ecoflex back in 1998, calls it an ideal blend partner for exactly those two.

One thing to know: BASF now also sells PBAT that's partly made from plants. So just seeing "PBAT" on a spec sheet doesn't tell you which kind you're getting. You have to ask.

The part that trips most people up is that "compostable" doesn't mean something breaks down anywhere. It means it passed a specific test under specific conditions, and there are two main kinds.

The first is industrial compostable. Commercial composting facilities run hot, around 58 degrees Celsius, and that's what this kind is tested for. To pass, at least 90% of the material has to break down within about six months, and the compost left behind has to be safe to grow plants in. In the US, the label you'll usually see is BPI, which certifies to a standard called ASTM D6400. In Europe, it's EN 13432.

The second is home compostable. That's tested at backyard pile temperatures, about 20 to 30 degrees Celsius, and the material gets up to 12 months to break down. The label to look for is TÜV OK compost HOME.

Why does that matter? Because, as the European Environment Agency points out, packaging that's industrially compostable won't necessarily break down fully in a backyard bin. So seeing the word "compostable" isn't enough. You want to know which kind.

EcoPackables products carry certifications for compostable packaging, including BPI, TÜV and ABA.

No. While some brands put "biodegradable" on their packaging in place of "compostable," it's an untested term. Basically, "biodegradable" means the material will break down eventually, but not where, how fast or under what conditions.

In a 2025 study in the journal Eco-Environment & Health, researchers tracked tiny PBAT particles in soil. After 150 days, only about 11 to 17% had broken down. As one of the researchers, Professor Fengxiao Zhu, put it, "Many people equate biodegradable with disappearing quickly, and that's not always the case."

That gap between what people hear and what actually happens is a big reason California has effectively banned "biodegradable" on product labels since 2022. So if a supplier calls their packaging "biodegradable" with no standard and no certificate behind it, treat that as a red flag.

Even certified compostable packaging only works if it actually gets composted. In October 2025, the Sustainable Packaging Coalition looked at composting access across the US. About 36% of people in its sample had some kind of composting program, but only 18.1% had one that takes compostable packaging, not just food scraps.

That's why the way you label it matters. When most people can't compost locally, the FTC's Green Guides say a compostable claim needs a clear note, something like "composting facilities may not exist in your area."

And if you sell in California, there's one more date to watch. A state law called AB 1201 will tie compostable claims to USDA organic program rules. That deadline is currently June 30, 2027, but the industry is asking for more time.

If you're buying or selling compostable packaging, here are five things to check.

1. Ask where it comes from. Is the PBAT fossil-based or partly plant-based? It shouldn't be called plant-based unless it is.
2. Ask for the certificate, not just the claim. Get the certificate number and look it up in the BPI or TÜV database.
3. Know which kind of compostable it is. Industrial or home? If your customers can't get to an industrial facility, home certification matters.
4. Drop "biodegradable" from your copy. Say "certified compostable," name the standard and add the qualifier.
5. Tell customers what to do with it. One line printed on the package can help make sure it ends up where it should.

Sources

• BASF, ecoflex (PBAT) product information
• European Environment Agency, briefing on biodegradable and compostable plastics (2020)
• ASTM D6400 and EN 13432 compostability standards; Biodegradable Products Institute (BPI)
• TÜV Austria, OK compost INDUSTRIAL and OK compost HOME certification schemes
• Hua et al., Eco-Environment & Health 4:100166 (2025)
• Sustainable Packaging Coalition, composting access data (October 2025)
• California Public Resources Code 42357; California AB 1201
• Federal Trade Commission, Green Guides (16 CFR 260.7)