What’s ASTM D6400 and Why Should I Care?

If you’ve spent any time evaluating compostable products in the US, you’ve seen the line on a hundred spec sheets: “Meets ASTM D6400.” It’s printed on packaging, listed on supplier websites, and used as the answer to almost every “is this actually compostable?” question. For most buyers, that line gets a nod and the conversation moves on.

It’s worth slowing down. ASTM D6400 is the technical specification underneath nearly every claim of “compostable” made about a product sold in the US. It backs the BPI Compostable Logo. It’s referenced in state laws across at least eight US states. It’s the standard the Federal Trade Commission’s Green Guides point to when defining defensible compostability claims. The way the standard is written — what it requires, what it doesn’t require, where it’s strict, where it’s flexible — shapes what “compostable” actually means in practice.

For a B2B buyer, foodservice operator, or sustainability program manager, knowing what’s in the standard, who tests for it, and how to verify a supplier actually meets it is the difference between specifying packaging that holds up to a real audit and specifying packaging that gets you in trouble at the worst possible moment.

The Short Definition

ASTM D6400 is the standard published by ASTM International (formerly the American Society for Testing and Materials) titled “Standard Specification for Labeling of Plastics Designed to be Aerobically Composted in Municipal or Industrial Facilities.”

The version most current at time of writing is D6400-23, indicating a 2023 revision of the standard originally published in 1999. ASTM standards get revisited every five to ten years; the substance has been stable since the early 2000s with minor methodological refinements.

The standard sets four substantive requirements that a product must meet to be labeled compostable in industrial conditions:

1. Biodegradation: at least 90% conversion of the test material’s organic carbon to CO2 within 180 days. For homopolymers and copolymers, the threshold is 60% with the rest of the carbon required to be in the form of biomass that is itself non-toxic.
2. Disintegration: at least 90% of the original mass must pass through a 2mm sieve after 84 days in a controlled composting test.
3. Ecotoxicity: the resulting compost must not negatively affect plant growth when tested per OECD 208 with two plant species.
4. Heavy metals: concentrations capped at 50% of the EPA Class A biosolid limits for arsenic, cadmium, chromium, copper, lead, mercury, molybdenum, nickel, selenium, and zinc.

The four pillars are tested independently. Failing any one means the product doesn’t meet the standard. There’s no partial credit.

Why the Standard Was Written

The 1999 publication of ASTM D6400 came at the tail end of a decade where “biodegradable” had become a marketing term with no defined meaning. Products carrying biodegradable claims included plastic bags that fragmented into microplastics rather than fully decomposed, food packaging that broke down only in lab conditions never actually achieved in the field, and items that biodegraded in technical sense but produced toxic residue.

ASTM convened a committee — D20 on Plastics, with subcommittee D20.96 on Environmentally Degradable Plastics — to develop a defensible standard for what “compostable” should actually mean. The result was D6400, defining a specific testing protocol and pass thresholds tied to actual composting facility conditions.

The standard’s authority grew because it was written collaboratively with input from compost facility operators, packaging manufacturers, and regulators. It reflects what compost facilities can actually process rather than what’s theoretically possible in a lab. This grounded design is part of why state laws and the FTC anchor to D6400 rather than to broader “biodegradability” claims.

Who Actually Tests for It

ASTM D6400 testing happens at accredited laboratories that follow the standard’s protocols. The US-based labs most commonly used by manufacturers include:

• Eden Research Laboratories (Pennsylvania)
• OWS (Belgium-based but conducts US-relevant testing)
• Intertek
• NSF International
• Specialized compostability labs operated by certifying bodies

The testing takes 6-12 months minimum because of the 180-day biodegradation window plus disintegration and ecotoxicity testing. Costs range from $20,000 to $50,000 for a full certification suite, depending on lab and product complexity.

The lab tests don’t certify products themselves. They produce test reports demonstrating compliance with D6400 thresholds. The certification step happens through programs like:

• BPI Compostable Logo (Biodegradable Products Institute): the most widely-recognized US compostability certification. Uses ASTM D6400 (and D6868 for paper products with bioplastic coatings) as the test specification basis.
• CMA (Compost Manufacturing Alliance): tests products under field conditions at actual composting facilities, providing field-validation on top of the lab-based ASTM compliance.

A product carrying the BPI logo has gone through D6400-conforming testing and is in BPI’s ongoing certification program with renewal cycles, audits, and annual fees.

State Laws That Reference It

This is where ASTM D6400 stops being just a technical specification and starts shaping commercial reality.

Washington (HB 1818, 2019): one of the first state laws restricting unsubstantiated compostable claims. Products labeled “compostable” in Washington must meet ASTM D6400 or D6868.

California (SB 1335 plus subsequent legislation): products labeled compostable must meet ASTM standards. California has been particularly active on PFAS bans that complement the compostability legal framework.

New York (S07382, 2022): restricts compostable claims to ASTM D6400 / D6868 compliant products.

Maryland: restricts compostable claims similarly.

Connecticut, Maine, Minnesota, Vermont: similar restrictions in various forms.

Most states with these laws empower the state attorney general or environmental agency to take enforcement action against products carrying false compostable claims. Penalties can include fines, recall orders, and stop-sale notices.

For a foodservice operator or product brand selling into multiple US states, the practical implication is that ASTM D6400 isn’t optional. A product without D6400 backing that carries a “compostable” label is at legal risk in any of these states.

What the FTC Says

The Federal Trade Commission’s Green Guides — published in 2012 and currently under revision — set the federal framework for environmental marketing claims. The FTC’s specific guidance on compostable claims:

• A product can only be marketed as compostable if all materials in the product break down into usable compost.
• The compostability claim must be qualified if the product cannot be composted in home compost (i.e., if it requires industrial composting).
• The qualifier must specify the type of facility required.
• Test data demonstrating compliance with a recognized standard (such as ASTM D6400) must support the claim.

In practice, FTC enforcement has been modest, but the agency has the authority to pursue cases against deceptive compostable claims. Companies marketing their products as compostable without D6400 backing operate in a vulnerable legal position.

D6400 vs D6868: What’s the Difference?

A frequent confusion point. Both are ASTM compostability standards but they cover different product categories.

D6400 applies to plastics (including bioplastics like PLA and PHA) and products made entirely from these materials.

D6868 applies to “single-use, plastic-coated paper” — products like coated paper cups, paper plates with bioplastic linings, and paper food containers with PLA or PHA coatings.

The substantive testing requirements are similar. The standards differ primarily in scope: D6400 governs the plastic itself; D6868 governs paper products with plastic components.

For a buyer evaluating a fiber-based product (like a paper cup or bagasse plate), D6868 may be the relevant standard rather than D6400. Reputable suppliers will specify which standard their product meets.

The Testing Reality

A few things buyers should know about how D6400 testing actually works:

Pilot-scale, not full-scale. D6400 testing happens in controlled lab conditions designed to simulate industrial composting facility conditions. Real facilities vary. A product that passes D6400 may underperform at a specific facility with different temperatures, retention times, or feedstock blend — or may overperform.

Test material matters. The certification covers the specific tested material formulation. A manufacturer that changes a coating chemistry, switches resin suppliers, or modifies the product structure may need re-testing. Some manufacturers play loose with this — selling a “D6400 compliant” product that has changed since certification.

Ongoing certification cycles. BPI requires annual renewal. Lapsed certification means the product no longer carries valid certification, even if the underlying material is unchanged.

No D6400 testing for home compost. D6400 covers industrial compost specifically. Home compost certification is a separate program (OK Compost HOME, DIN-Geprüft Home Compostable) with stricter requirements at lower temperatures.

How to Verify a Supplier’s D6400 Claim

A practical due-diligence checklist:

1. Ask for the certification number. Reputable certified products have a BPI certificate number that can be looked up in BPI’s product database. CMA-approved products have similar lookup.

2. Check the certification database directly. BPI maintains a searchable database at bpiworld.org. The product, brand, and certificate number should match what the supplier claims.

3. Request the test report. Suppliers should be able to produce the actual D6400 test report on request. The report should be from an accredited lab and dated within the certification cycle.

4. Verify the certification is current. Certifications expire. A certificate dated 2019 with no renewal evidence is not currently valid even if the product is unchanged.

5. Check for material consistency. Ask if the tested material matches the product currently being sold. Material substitutions that should have triggered re-testing are a red flag.

6. Cross-reference against state law databases. California’s CalRecycle and Washington’s Department of Ecology maintain public databases of compostable products meeting state requirements. A product not on these lists may have a paper certification but lack state-level compliance.

For a B2B buyer placing a meaningful order, doing this verification once on a new supplier prevents most of the surprises that come up in audits, regulatory inquiries, or customer complaints.

What ASTM D6400 Doesn’t Cover

Worth being clear about the standard’s limits.

It doesn’t certify home compost. Home composting is a separate certification.

It doesn’t certify marine biodegradability. A product that breaks down in industrial compost may persist in marine environments. Marine biodegradability has separate standards (ASTM D7081 for some applications).

It doesn’t certify environmental benefit. A D6400-compliant product still requires industrial composting infrastructure to actually compost. Without that infrastructure, the product ends up in landfill regardless of certification.

It doesn’t certify food safety. Food contact safety is governed by FDA regulations separately.

It doesn’t certify carbon footprint or lifecycle benefit. A compostable product may have a higher overall lifecycle impact than a non-compostable alternative depending on manufacturing inputs and end-of-life handling.

The standard answers one question — “will this break down in an industrial composting facility under defined conditions?” — and answers it well. It doesn’t answer the broader environmental questions.

The Common Misunderstandings

A few patterns that recur in buyer conversations:

Confusing compostable and biodegradable. Biodegradable means it will eventually break down under some conditions. Compostable means it meets a specific standard with defined thresholds and a defined facility type. ASTM D6400 certifies the second; it does not certify the first.

Treating “ASTM compliant” as the same as “BPI certified.” A product can claim ASTM compliance based on a one-off lab test without being in an ongoing certification program. BPI certification adds the ongoing audit, renewal, and database listing that lab compliance alone doesn’t include.

Assuming D6400 means home compostable. It doesn’t. A D6400 product is industrial-only unless additionally certified.

Confusing “compostable” with “recyclable.” They’re different end-of-life pathways requiring different infrastructure and different consumer behavior. A compostable product is generally not recyclable through plastic recycling streams.

Believing the certification is permanent. It isn’t. Certifications expire and require renewal.

How D6400 Connects to Procurement

For a foodservice operator or sustainability manager building a compostable program, ASTM D6400 is the technical anchor for almost every product specification. A working procurement spec includes:

• Required: ASTM D6400 or D6868 compliance, current BPI certification, certificate number provided, supplier audit acceptance
• Strong preference: PFAS-free documentation (testing below detection limits per EPA Method 1633), state-database listing for primary sales states
• Optional: home compost certification, CMA field validation, marine biodegradability if relevant to use case

For B2B operators sourcing across categories — compostable food containers, compostable cups and straws, compostable utensils — having the same procurement spec across SKUs simplifies audits and reduces the risk of inconsistent compliance across the catalog. A coordinated supplier relationship that documents D6400 / D6868 status across the full product range is more reliable than mixing-and-matching across multiple suppliers with varying documentation discipline.

When You Don’t Need D6400

For some applications, the standard isn’t strictly necessary.

Internal company use without compostability claims: a company using compostable-style products internally without marketing them as compostable doesn’t need certification. The products may still be useful for waste-stream sorting, but the absence of a public compostability claim removes the legal exposure.

Markets without state laws: some US states don’t regulate compostable claims as tightly. Selling exclusively into those markets reduces the legal pressure for D6400 backing — though customer expectations may still demand it.

Internal sustainability tracking: lifecycle tools and reporting frameworks may accept evidence of compostability beyond formal D6400 certification. For internal accounting, less formal documentation can be sufficient.

For most commercial applications selling into US markets, D6400 backing is the working baseline.

The Quiet Anchor

ASTM D6400 isn’t the most visible piece of the compostable packaging conversation. It’s a technical specification most consumers will never read. But it’s the anchor underneath almost every compostable claim made in the US market, and it shapes both what the products actually do and what the regulators will accept.

For a buyer, the practical takeaway is small but consistent: when a supplier says compostable, ask about ASTM D6400. Get the certificate number. Check the database. Verify the certification is current. Document the answer in the procurement file. The five-minute due diligence prevents the much-larger headaches that come from an audit, a state attorney general inquiry, or a customer complaint.

The standard does its work quietly. It enforces a definition of compostable that’s testable, defensible, and tied to actual industrial composting facility conditions. The compostable products that meet it really do break down where the infrastructure exists. The ones that don’t, don’t.

That’s why a buyer should care. The line on the spec sheet — “meets ASTM D6400” — translates directly to the product behaving the way the marketing implies. When the line is real, the rest of the compostable program works. When the line is missing or unverifiable, the whole program is on shaky ground.

Get the standard right, and the rest of the compostable conversation gets simpler.