What Does BPI Certified Compostable Mean?

BPI certified means a product has been independently tested and verified to break down in a commercial or industrial composting facility within a set time frame, leaving no toxic residue or plastic fragments behind. BPI is the Biodegradable Products Institute, the main certifier of compostable products in North America, and its logo appears on compostable trash bags, food scrap liners, cups, cutlery and takeout containers. What BPI certification does not mean is that a bag will break down in your backyard compost bin. Commercial facilities run hotter and more consistently than most home piles, so a BPI bag that disappears in a few months at a municipal site can sit half-intact in a backyard heap for far longer. Here’s what the label covers, how it compares with “biodegradable” and “home compostable,” and which bags actually belong in a home pile.

In this guide

1. What BPI Certification Covers
2. Commercial vs Home Composting
3. Biodegradable vs Compostable
4. Can You Put BPI Bags in a Backyard Compost Pile?
5. Using BPI Bags With Curbside or Drop-Off Composting
6. How to Spot a Certified Compostable Bag
7. What BPI Certification Doesn’t Tell You
8. Which Bag to Use Where
9. Storing and Using Compostable Bags
10. Frequently Asked Questions

What BPI Certification Covers

To earn BPI certification, a manufacturer submits its product for lab testing against recognized standards. For plastic products such as bags and cutlery, that’s ASTM D6400; for paper or fiber products with a plastic coating or lining, it’s ASTM D6868. The tests check that the material:

• Disintegrates: breaks into pieces small enough that they aren’t visible in finished compost within a set period under commercial composting conditions.
• Biodegrades: is converted to carbon dioxide, water and biomass by microbes at a rate comparable to known compostable materials, rather than just crumbling into microplastic.
• Leaves no harm: the resulting compost doesn’t contain heavy metals above set limits and doesn’t harm plant growth.

BPI also requires certified products to be free of intentionally added fluorinated chemicals, the PFAS family once common in grease-resistant food packaging, and sets limits on total fluorine. That’s useful if you’re spreading finished compost on a vegetable garden.

Certification applies to a specific product, not a whole brand. A company can sell BPI-certified bags alongside uncertified ones. Look for the BPI logo with a certification number on the product or box, and you can verify the listing in BPI’s public product catalog.

BPI itself is a nonprofit membership organization rather than a government agency. Its role is to confirm, through independent lab results, that a product meets the published compostability standards, and to license the logo to products that pass. That makes it different from a self-declared claim printed by a manufacturer, which is why compost facilities and city programs in the US and Canada often reference BPI certification by name in their rules.

Commercial vs Home Composting

The reason BPI bags don’t always break down at home comes down to conditions. Commercial compost facilities build large windrows or in-vessel systems that hold thermophilic temperatures, often well above 130°F, for weeks, with controlled moisture and frequent turning. Those conditions break down compostable plastics such as PLA (polylactic acid) and PBAT blends that are common in compostable bags.

Most backyard piles never reach those temperatures, or reach them only briefly in the center. Cold or slow piles may stay at ambient temperature for months. Compostable plastic in a home pile can take far longer to break down, and you may find stretched, shredded film when you harvest. Our guide to hot vs cold composting explains the difference in more detail.

Label	What it means	Backyard pile?
BPI Certified Compostable	Tested to break down in commercial or industrial composting (ASTM D6400 or D6868), PFAS limits	Not guaranteed; slow in most home piles
Home compostable certification (e.g., TÜV Austria OK compost HOME)	Tested to break down at lower, home-pile temperatures	Yes, designed for it
“Compostable” with no certification logo	Unverified claim	Unknown
“Biodegradable” or “eco-friendly”	No specific time frame or conditions; may only fragment	No
“Oxo-degradable” or “degradable”	Conventional plastic with additives that make it fragment	No; creates microplastics
Plain kraft paper bag (uncoated)	Paper fiber	Yes, shred or tear it

Biodegradable vs Compostable

These terms sound similar, but they mean very different things. Technically, almost everything biodegrades eventually; the word on its own carries no time frame and no conditions. A conventional plastic bag labeled “biodegradable” may contain additives that make it break into smaller pieces faster, which is worse for soil, not better. That’s why some states, including California, restrict or ban “biodegradable” claims on plastic products, and why compost programs typically reject bags labeled only as biodegradable.

“Compostable,” backed by a third-party certification, means the product has been tested to fully break down under specific composting conditions within a set period. That’s the claim to look for. If a box says “biodegradable trash bags” or “bio bags” without a BPI or home-compostable logo, treat it as an ordinary plastic bag for compost purposes.

Can You Put BPI Bags in a Backyard Compost Pile?

You can, but expect slow results. If you’re going to try it, these steps help:

• Tear or cut the bag. Shredding the film into strips dramatically increases surface area and exposure to microbes.
• Bury it in the hot center. Place bag pieces in the middle of an active pile, not on the surface.
• Run a hot pile. A pile at least 3 feet by 3 feet by 3 feet with a good mix of greens and browns, kept as moist as a wrung-out sponge and turned regularly, gets closest to commercial conditions. Our guide to making compost faster covers how.
• Screen finished compost. Sift out any fragments and toss them back in for another round.
• Keep plastic volume low. A few liners a month is manageable; a household’s worth every week will overwhelm a home pile.

Better options for home composting: use an uncoated paper bag, a few layers of newspaper or no liner at all in your countertop bin. Empty the scraps straight into the pile and rinse the bin. Our tips on storing food scraps for compost cover ways to keep a liner-free bin from smelling, and if you want a dedicated bin, see our roundup of countertop compost bins.

Using BPI Bags With Curbside or Drop-Off Composting

This is where BPI-certified bags make the most sense. Many municipal and private food-scrap programs accept, or even require, certified compostable liners because they keep carts cleaner and are designed to break down in the facility’s process. But policies vary widely:

• Some programs accept only BPI-certified bags and reject any other “compostable” or “biodegradable” bag.
• Some accept only paper bags because sorting equipment can’t tell certified plastic from regular plastic.
• Some don’t accept any bags and want scraps loose.
• Many accept compostable bags but not compostable cups, cutlery or takeout containers, which can look too much like conventional plastic.

Check your program’s accepted materials list before you buy. A certified bag that ends up in the wrong cart is a contaminant either way: in recycling, compostable plastic contaminates the plastic stream, and in landfill, without oxygen and microbes, it breaks down very slowly, much like regular plastic.

How to Spot a Certified Compostable Bag

• Look for the logo. A BPI mark with a certification number, or a home-compostable mark from a recognized certifier.
• Check the color and markings. Several states, including California and Washington, have laws requiring compostable products to be readily distinguishable from regular plastic, which is why many certified bags are green or brown and printed with “compostable.”
• Search the catalog. BPI publishes a list of certified products online; search by brand or product name.
• Ignore vague claims. “Earth-friendly,” “plant-based,” “green” and “biodegradable” mean nothing on their own for compost purposes.

Our roundup of the best compostable bags compares certified options by size and strength.

What BPI Certification Doesn’t Tell You

The logo answers one question well: will this break down in a properly run commercial compost facility? It leaves several others open.

• Strength and leak resistance. Certification doesn’t test how well a bag holds wet coffee grounds or melon rinds. Thickness and size vary a lot between certified brands.
• Shelf life. Certified bags can become brittle or sticky after months in a hot garage. The certification says nothing about storage.
• Where the raw materials came from. Plant-based content, recycled content and carbon footprint are separate claims, and certified compostable plastics can be made partly from fossil-based polymers that still meet the compostability standard.
• Whether your local facility accepts it. That depends entirely on your program.
• Home-pile performance. As covered above, BPI doesn’t test at backyard temperatures.

Which Bag to Use Where

Situation	Best choice
Kitchen scraps going to a backyard pile or tumbler	No liner, a paper bag, or a certified home-compostable bag
Kitchen scraps going to a curbside food-scrap cart	Whatever your program specifies, often a BPI-certified bag or paper
Kitchen scraps going to a worm bin	No liner; plastics of any kind don’t suit worm bins
Leaves and yard waste for curbside pickup	Uncoated paper lawn and leaf bags
Regular household trash headed to landfill	Ordinary trash bags; compostable bags offer little benefit there

Storing and Using Compostable Bags

Compostable bags are designed to break down, so they have a shorter shelf life than regular plastic and can weaken with heat, humidity and moisture from wet food scraps. Buy only a few months’ supply at a time, store them in a cool, dry place out of direct sun, and use them in a ventilated countertop bin rather than a sealed one so condensation doesn’t soften the film. Empty the bin every few days, and don’t pour liquids into a compostable liner.

For lawn and garden waste, uncoated paper lawn and leaf bags are almost always the better choice; many yard-waste programs require them, and they compost readily in a home pile too. For more on building and maintaining a pile, start with our composting and soil guide.