BPI certification and OK Compost certification both matter, but they answer different questions: BPI (paired with ASTM D6400) confirms a bag is certified compostable in a commercial facility in the United States, while OK Compost HOME and OK Compost INDUSTRIAL (from TUV Austria) confirm compostability in backyard conditions or industrial facilities, often with European testing behind EN 13432. Understanding compostable bag certifications is less about picking a "better" label and more about knowing which certification matches where you actually plan to compost.
What Are Compostable Bag Certifications?
A compostable bag certification is an independent, third-party confirmation that a product has been laboratory-tested and meets a defined standard for breaking down into carbon dioxide, water, and organic matter, without leaving toxic residue or microplastics behind. Certification is not a marketing label a brand applies to itself. It is granted by an accredited certifying body after a manufacturer submits products for testing against a recognized standard.
The certifications most commonly seen on compostable bags are BPI (Biodegradable Products Institute), TUV Austria's OK Compost HOME and OK Compost INDUSTRIAL marks, and compliance with the ASTM D6400 standard (used in the USA) or EN 13432 (used in the EU). These are not competing claims. They often appear together on the same product, because each one verifies a different aspect of compostability, such as which composting environment the product is designed for.
How Do Compostable Bag Certifications Actually Work?
Certification works by testing a product's disintegration, biodegradation, and ecotoxicity under controlled, repeatable conditions, then comparing the results against a pass or fail threshold. A bag is not certified because a manufacturer says the material is "plant-based" or "compostable." It is certified because a lab measured how much of the material broke down, how quickly, and whether any residue was harmful to plant growth.
Two distinct composting environments are tested, and this is the most important distinction for readers to understand:
- Industrial composting uses high heat (55-60 degrees C), controlled humidity, and active microbial activity inside a commercial facility. Testing standards here are ASTM D6400 (USA) and EN 13432 (EU), with BPI and OK Compost INDUSTRIAL as the certifying marks.
- Home composting relies on ambient outdoor temperatures in a standard backyard compost pile, without the sustained heat of an industrial facility. The relevant standard here is TUV's OK Compost HOME.
Because these two environments produce very different conditions, a bag that is certified for industrial composting will not necessarily break down at the same rate, or at all, in a backyard bin. This is why checking which specific certification appears on a product matters more than simply seeing the word "compostable" on the package.
What Do BPI and OK Compost Certifications Actually Require?
This is where compostable bag certifications move from marketing language into measurable evidence. Under ASTM D6400, a certified product must demonstrate 90% disintegration within 84 days under industrial composting conditions. EN 13432 sets a similar bar, requiring 90% disintegration within 90 days. BPI certification specifically requires independent third-party laboratory testing; it is not a self-declared claim, and products must demonstrate compliance before certification is granted.
Home composting operates on a longer timeline because conditions are less controlled. TUV's OK Compost HOME standard requires 90% disintegration within 180 days under ambient backyard composting conditions.
In practical terms, this means:
- A product labeled "BPI certified" or "ASTM D6400 compliant" has been tested for industrial composting facility conditions.
- A product labeled "OK Compost HOME" has been tested and shown to break down in a standard backyard compost environment.
- A product labeled "OK Compost INDUSTRIAL" has met the same type of industrial threshold, verified through TUV Austria rather than BPI.
- EN 13432 is the European equivalent of ASTM D6400, used for industrial composting compliance in the EU.
GreeneWrap trash bags, food storage bags, and cling wrap are BPI certified, TUV Austria certified, OK Compost HOME certified, OK Compost INDUSTRIAL certified, and meet both ASTM D6400 and EN 13432 standards. That combination means the products have been independently tested for both home and industrial composting environments, rather than one or the other. GreeneWrap products are also PFAS free and fluorine free, confirmed by the manufacturer; this is a separate claim from compostability certification and applies specifically to GreeneWrap products, not the compostable bag category as a whole. Some compostable products on the market may contain PFAS, so checking certification and manufacturer confirmation directly is the only reliable way to know.
Which Compostable Bag Certifications Actually Matter?
For most readers evaluating compostable bag certifications, the honest answer is that the certification that matters is the one that matches your composting setup, not the one with the most recognizable logo. If you compost in a backyard bin or pile, OK Compost HOME is the certification that tells you the product was tested for that environment. If your bag is going into a municipal green-bin program or you're relying on a commercial composting facility, BPI certification and ASTM D6400 compliance (or EN 13432 in the EU) are the relevant marks.
A product carrying only an industrial certification should not be assumed to work in a home compost pile, and a home-certified product is not making a claim about industrial facility performance unless it also carries that separate mark. Bags that carry both sets of certifications, as GreeneWrap products do, are tested and verified for either use case, which is useful for households who aren't certain which composting path they'll use, or who use both depending on the season or type of waste.
It's worth repeating a point that applies to all compostable products regardless of brand: compostable bags are designed for active composting environments, not landfills. Like all organic materials, biodegradation occurs significantly slower in landfill conditions due to limited oxygen and moisture. Certification testing is specific to composting conditions, and no certification claims landfill performance.
How Do You Verify Compostable Bag Certifications and Spot Greenwashing?
Because "compostable" is not a legally protected term everywhere it's used, verifying a specific certification mark is the most reliable way to confirm a product's claims. A few practical checks:
- Look for the actual certification logo or number, not just the word "compostable" printed on the packaging. BPI, TUV Austria, and OK Compost logos typically include a certification number that can be checked against the certifying body's public database.
- Check which standard is cited: ASTM D6400 and EN 13432 both refer to industrial composting; OK Compost HOME refers specifically to backyard conditions. If a package only says "compostable" with no standard or certifying body named, that is a signal to look closer.
- Be cautious of the word "biodegradable" used alone. Biodegradable is a broader, less regulated term that does not guarantee a specific timeframe, environment, or lack of toxic residue the way a certified compostable claim does. A product can be technically biodegradable over an unspecified and very long period without meeting any compostability standard at all.
- Confirm claims that go beyond compostability, such as PFAS-free status, separately. Compostability certification does not automatically confirm a product is free of PFAS or other additives; that is typically a separate manufacturer confirmation.
Readers researching the difference between biodegradable and compostable claims should know that compostable is a certifiable, testable claim with defined timeframes and residue requirements, while biodegradable describes a general process that organic materials undergo without a guaranteed timeline or environmental standard attached.
What Should You Look for When Buying Compostable Bags?
In practice, matching the certification to your actual composting situation is the most useful step a buyer can take:
- If you compost at home in a backyard bin or pile, confirm the product is specifically OK Compost HOME certified, not just industrially certified.
- If you use a municipal green-bin or curbside composting program, check with your local program first. Many municipal facilities require BPI certification or ASTM D6400 compliance specifically, and some only accept bags on an approved list regardless of certification.
- If you're using bags for wet food scraps, keep in mind that compostable bags are suitable for wet waste for short-term use; waste should not sit in the bag for more than 1-2 days, since moisture accelerates the breakdown process and can compromise the bag before it reaches the compost pile.
- Sharp items such as broken glass or bones can puncture any compostable bag, a limitation common to the category and not specific to any one brand.
- Store compostable bags in a cool, dry place and use them within 12 months of purchase, since the same microbial-friendly materials that allow composting can also respond to storage conditions over time.
Checking for multiple certifications on one product, rather than a single generic "compostable" claim, is generally a stronger indicator that a manufacturer has invested in third-party testing rather than relying on self-declared language.
FAQ
Is BPI certification better than OK Compost certification?
Neither is inherently better; they test for different composting environments. BPI certification, paired with ASTM D6400, verifies industrial composting performance in the US. OK Compost INDUSTRIAL (TUV Austria) verifies the same type of industrial performance through a different certifying body, while OK Compost HOME verifies backyard composting specifically. The right certification depends on where you plan to compost the bag.
Can a bag be both BPI certified and OK Compost certified?
Yes. Many compostable products, including GreeneWrap trash bags and food storage bags, hold BPI certification, TUV Austria certification, OK Compost HOME certification, and OK Compost INDUSTRIAL certification simultaneously, along with compliance with ASTM D6400 and EN 13432. Holding multiple certifications means the product has been independently tested for more than one composting environment.
Does a compostable bag certification mean the bag will break down in my trash can or a landfill?
No. Compostable bag certifications are based on testing in active composting environments, either industrial facilities or backyard compost piles, where heat, moisture, and microbial activity are present. Compostable bags are designed for active composting environments, not landfills, and biodegradation occurs significantly slower in landfill conditions due to limited oxygen and moisture.
How do I know if a municipal compost program accepts my certified compostable bag?
Certification is necessary but not always sufficient for municipal acceptance. Many city or county composting programs maintain their own approved list, often requiring BPI certification or ASTM D6400 compliance at minimum. Checking directly with your local program before use is the most reliable way to confirm acceptance.
What's the difference between "compostable" and "biodegradable" on a bag label?
Compostable is a certifiable claim tied to a specific standard (such as ASTM D6400, EN 13432, or OK Compost HOME), a defined disintegration timeframe, and a requirement that no toxic residue remains. Biodegradable is a broader term describing that a material will eventually break down through natural processes, but without a guaranteed timeframe, environment, or residue standard attached. A product can be biodegradable without being certified compostable.