If you've searched for biodegradable bags vs compostable bags and come away more confused than when you started, you're not alone. The two words get used interchangeably on packaging, in product listings, and in casual conversation, but they describe two very different things. One is a marketing term with no required proof. The other is a certified claim backed by third-party lab testing. That distinction matters more than most shoppers realize, and it's becoming a legal one too.
Biodegradable Bags vs Compostable Bags: What's Actually Different
"Biodegradable" simply means a material will eventually break down through microbial activity. That's it. There's no required timeframe, no required testing, and no independent body checking the claim before it goes on a label. A plastic bag technically biodegrades, it just might take decades or centuries to do it, and it can leave behind microplastic fragments along the way.
"Compostable" is a different category entirely. To legally use the term in a certified context, a product has to pass third-party testing against a recognized standard, prove it breaks down into carbon dioxide, water, and organic matter within a specific timeframe, and leave no toxic residue behind. Compostable is a regulated, testable outcome. Biodegradable is a vague promise.
This is the core reason we never describe GreeneWrap products as biodegradable, even though it's technically true that compostable materials also biodegrade. We use certified compostable language instead, because that's the claim we can actually back up with testing.
Why "Biodegradable" Is a Vague Claim
Here's the problem with biodegradable as a standalone claim: it tells you nothing about how long the process takes or what's left behind. A product can call itself biodegradable and still take 500 years to break down in the wrong conditions. There's no standard timeframe attached to the word, and no requirement to prove disintegration or eliminate toxic residue.
Compostable claims solve this by requiring specific, measurable outcomes. Under ASTM D6400 in the US and EN 13432 in the EU, a product has to reach 90% disintegration within a defined window under industrial composting conditions, meaning high heat, humidity, and microbial activity in a commercial facility. That's a testable benchmark. "Eventually biodegrades" is not.
This is exactly why California prohibits the term "biodegradable" on plastic product labels. The claim can't be verified, so regulators decided it shouldn't be marketed as an environmental benefit. That's not an overreach, it's a reasonable response to a claim that was never backed by data in the first place.
What Certification Actually Requires
BPI certification, one of the standards GreeneWrap products carry, requires independent third-party laboratory testing. It is not a self-declared claim a company can slap on packaging after an internal review. Products have to demonstrate compliance with recognized standards before certification is granted, and that testing covers disintegration rate, biodegradation percentage, and absence of toxic residue in the finished compost.
There are two separate certification paths worth understanding:
- Industrial composting (ASTM D6400 / EN 13432): Requires high temperatures around 55-60°C, controlled humidity, and microbial activity found in a commercial composting facility. Products must reach 90% disintegration within 84 days under ASTM D6400 or 90 days under EN 13432.
- Home composting (TUV OK Compost HOME): Tests performance at ambient temperature in a standard backyard compost environment, with a 180-day window for 90% disintegration.
GreeneWrap's full product line, including our compostable trash bags and food storage bags, is BPI certified, TUV Austria certified, OK Compost HOME certified, and OK Compost INDUSTRIAL certified, meeting both ASTM D6400 and EN 13432 standards. That's four separate certification marks, each requiring its own testing process. A biodegradable claim requires zero.
California AB 1201 and Why This Distinction Is Now Law
This isn't just a labeling preference anymore, it's codified. California AB 1201 was signed into law specifically to address the confusion between vague biodegradable claims and genuine certified compostable products. The law requires that any product labeled compostable be third-party certified, prohibits products containing PFAS from carrying a compostable label, and bans deceptive look-alike products that visually mimic certified compostable items without meeting the actual standard.
The law exists because the industry had a real problem. Non-compostable products that looked identical to certified ones were showing up in curbside bins and backyard piles, contaminating composting systems and, in some cases, farmland soil. Consumers had no reliable way to tell the difference just by looking at a bag. AB 1201 also directs CalRecycle to develop clearer labeling requirements going forward, which should make this distinction easier to spot at a glance in the coming years.
We think this is a good law. Composting infrastructure only works if the inputs are actually compostable. A single batch of contaminated fiber or plastic can force a facility to reject an entire load, and that undermines the whole system for everyone participating in good faith.
PFAS: The Hidden Issue Behind Some "Compostable" Products
One of the reasons AB 1201 specifically targets PFAS is that some compostable fiber products, particularly molded fiber and paper-based items, have historically contained intentionally added fluorine compounds for grease or water resistance. These persist through the composting process and end up in the finished compost, which then gets applied to farmland or gardens. BPI no longer certifies compostable fiber products with intentionally added fluorine, which is a meaningful shift in the standard.
It's worth being direct here: some compostable products may contain PFAS, and certification alone doesn't automatically guarantee a fluorine-free product unless that's specifically confirmed. Always check for that confirmation rather than assuming it.
GreeneWrap products are PFAS free and fluorine free, confirmed directly by our manufacturer. That's specific to our products, not a blanket industry claim, and we'd rather state it that precisely than let anyone assume it applies more broadly than it does.
What Compostable Certification Does Not Promise
Certification is powerful, but it doesn't mean a bag will break down anywhere you put it. Compostable bags are designed for active composting environments, not landfills, not the ocean, and not sitting in a regular trash bin. Like all organic materials, compostable bags decompose more slowly in landfill conditions where oxygen and moisture are limited. That's not a flaw in the product, it's just how the certification is designed to work: active heat, moisture, and microbial activity trigger the breakdown, and a sealed landfill doesn't provide those conditions.
This is also why compostable and biodegradable get confused so often. People assume "compostable" means a bag will magically vanish wherever it ends up. It won't. It needs the right environment, whether that's a backyard bin, a curbside compost program, or an industrial facility.
How to Dispose of Compostable Bags Correctly
Getting the benefit of certification means using the right disposal path:
- Industrial composting facility: The most reliable option for bags certified under ASTM D6400 or BPI, since these facilities hit the temperature and humidity thresholds required for full breakdown.
- Curbside composting program: Most US municipal composting programs accept BPI certified bags, but policies vary by city. Always check your local guidelines and confirm they specifically require BPI certification before assuming your bag qualifies.
- Backyard compost bin: Only for bags carrying the TUV OK Compost HOME certification, since backyard conditions run cooler than industrial facilities and need a product tested for that environment specifically.
If you're using a bag for wet food scraps, that's a good fit for short-term use, but don't leave wet waste sitting in the bag for more than a day or two. Moisture accelerates breakdown, and you don't want that process starting before the bag reaches the compost pile.
Choosing Products With Real Certification Behind Them
Once you understand the difference, shopping gets a lot simpler. Skip anything labeled just "biodegradable" with no certification mark attached. Look for BPI certified, ASTM D6400 compliant, EN 13432 compliant, or OK Compost HOME language specifically. Those are testable claims, not marketing language.
Our compostable food bags and trash bag lineup carry all four certifications across every size, from 1-2 gallon kitchen bags up to 90-95 gallon yard waste bags for heavier jobs. That consistency matters if you're trying to build a household or business habit around genuinely compostable products rather than guessing based on packaging language.
The Bottom Line
Biodegradable and compostable are not interchangeable, no matter how often they appear side by side on a shelf. Biodegradable is a claim anyone can make without proof. Compostable, when properly certified, is a tested outcome backed by independent labs and specific breakdown standards. With laws like AB 1201 now putting legal weight behind that distinction, it's worth learning to spot the difference before your next purchase, not after.
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