When people see the words “compostable” on a bag or package, many wonder what it really means. I have noticed this question often comes up in stores, online, and even in Reddit discussions. One term that appears again and again is ASTM D6400.
If you work with compostable bags, packaging films, or materials like PLA and PBAT, you will see this standard often. But what does it truly mean? And how does it connect to certifications like BPI Certification?
This guide explains ASTM D6400 in a simple and clear way. I want you to understand what it tests, how products meet it, and why businesses rely on it today.
Why Do People Search for ASTM D6400?
People search for ASTM D6400 because the term appears on many compostable products. But these same people are unsure about:
- Whether it means “biodegradable”
- Whether it is the same as BPI Certification
- How long something takes to break down
- Whether the product is safe for soil
I have seen many users on social media mix up the meanings. Some think it is a certification. Some think it guarantees home composting. Neither is correct. This article clears up these misunderstandings.
What Is ASTM D6400?
ASTM D6400 is a U.S. standard for testing industrial compostable plastics. It sets rules for how a plastic material should behave in a commercial composting facility.
This type of facility uses high heat, controlled airflow, and active microorganisms. Your home compost pile cannot reach the same conditions.
So, ASTM D6400 answers one main question: Can this plastic fully break down in an industrial composting environment without harming the compost?
It applies to plastics such as:
- PBAT blends
- PLA materials
- Compostable bags
- Compostable films
One important thing to remember is this:
ASTM does not give certifications. It provides test methods.
Some companies say they sell “ASTM D6400 certified bags.” That is not correct. The right phrase is “ASTM D6400 compliant.”
What Does ASTM D6400 Certify?
I see this confusion everywhere—especially on Reddit and LinkedIn.
Here is the truth:
- ASTM D6400 = test standard
- BPI Certification = official approval
BPI uses ASTM D6400 (and ASTM D6868) to check whether a product qualifies as industrial compostable. Only BPI can issue a certification mark for the U.S. market.
So if you want a product that is officially recognized, you look for BPI Certified Compostable, not “ASTM certified.”
Requirements of ASTM D6400
ASTM D6400 includes several scientific tests. These tests confirm whether a plastic material can break down safely in a commercial compost system.
Below are the main requirements, written in simple terms.
1. Biodegradation Test
The material must convert into:
- carbon dioxide
- water
- biomass
It cannot leave microplastic fragments.
This process must follow the biodegradation curve defined in the standard (ASTM International, 2019).
2. Disintegration Test (84 Days / 12 Weeks)
After 12 weeks in a composting system:
- The product must break into small pieces
- No large visible fragments should remain
- Most pieces must be under 2 mm
This prevents contamination of finished compost.
3. Heavy Metal Limits
The material must stay below strict limits for metals like:
- lead
- cadmium
- mercury
- hexavalent chromium
These metals harm soil and plants if levels are too high.
4. Ecotoxicity Test (Plant Safety)
Compost made from the material must support plant growth.
Plants must grow at least as well as plants grown in regular compost.
This test prevents harmful chemicals from entering the soil.
5. Ingredient Review and Safety Rules
Manufacturers must provide full ingredient disclosures.
This includes additives, colorants, and fillers.
Unsafe materials cannot be used.
Which Products Must Meet ASTM D6400?
You will find ASTM D6400 mentioned on many compostable products, including:
- food waste bags
- grocery bags
- compostable mailers
- PLA cups and cutlery
- packaging films
- compostable liners for bins
If a product claims to be “compostable plastic,” it is often referring to D6400 testing.
ASTM D6400 vs ASTM D6868
These two standards are often paired, but they apply to different things.
| Standard | Applies To | Notes |
|---|---|---|
| ASTM D6400 | Compostable plastics | Used for bags, films, resins |
| ASTM D6868 | Paper + compostable coating | Used for cups, paper trays, packaging |
ASTM D6868 is for fiber-based items with a compostable coating.
ASTM D6400 is for the plastic components themselves.
ASTM D6400 vs EN 13432
EN 13432 is Europe’s industrial compostable packaging standard.
It is similar to ASTM D6400 but used in EU markets.
| Criteria | ASTM D6400 (U.S.) | EN 13432 (EU) |
|---|---|---|
| Region | United States | European Union |
| Scope | Plastics | Packaging materials |
| Disintegration Test | 84 days | 90 days |
| Biodegradation | ~90% in 180 days | Similar requirement |
| Certification Bodies | BPI | TÜV Austria, DIN CERTCO |
If you sell products globally, you may need compliance with both.
ASTM D6400 vs BPI Certification
Here is the simplest answer:
- ASTM D6400 is the test method.
- BPI Certification is the proof that a finished product meets the test.
BPI checks:
- ingredient safety
- labeling
- product-level performance
- updated PFAS rules
So, ASTM D6400 is only one part of the full process.
How ASTM D6400 Testing Works (Step-by-Step)
Here is a simplified view of the testing process:
- A company sends product samples to an accredited lab.
- The lab runs a biodegradation test.
- The product goes through a disintegration trial for 12 weeks.
- Heavy metals and chemical safety tests follow.
- The lab issues a report.
- The company uses this report to apply for BPI Certification.
This entire process typically takes several months.
Common Misunderstandings About ASTM D6400
I’ve seen these points misunderstood the most:
1. “ASTM certified” is not a real term.
ASTM does not certify products.
2. Oxo-biodegradable plastics do not meet D6400.
They break into microplastics, not compost.
3. Home compost is not enough.
ASTM D6400 is for industrial composting only.
4. Resin certification ≠ final product certification
The finished item must be tested again.
How to Know If Something Meets ASTM D6400
Here are simple steps you can use:
1. Check the BPI Database
If a product meets ASTM D6400, it often becomes BPI certified.
Search the product or company name.
2. Ask for the ASTM D6400 compliance report
Manufacturers can request this from testing labs.
3. Look for accurate labeling
Products should say “meets ASTM D6400” or “BPI Certified Compostable.”
4. Avoid vague claims
Terms like “eco-friendly” or “biodegradable” do not mean D6400 compliant.
Why ASTM D6400 Matters to Businesses
ASTM D6400 is more than a technical document. It affects:
- waste programs
- retailer requirements
- supplier compliance
- brand credibility
- environmental claims
Many composting facilities in the United States accept only packaging that meets ASTM D6400 and is BPI certified.
This keeps their compost clean and safe.
Simple Examples of ASTM D6400-Compliant Products
Here are common items that follow this standard:
- food scrap bags
- compostable shopping bags
- PLA cup lids
- bio-based films
- paper cups with compostable coatings (D6868)
These items help reduce landfill waste when used in the right systems.
FAQ About ASTM D6400
Is ASTM D6400 the same as compostable?
No. It defines how to test compostability. It does not guarantee certification.
Does ASTM D6400 mean biodegradable?
It means industrial compostable, not general biodegradability.
Does BPI require ASTM D6400?
Yes. BPI Certification uses ASTM D6400 and ASTM D6868 as core standards.
Can ASTM D6400 products be home composted?
No. Home compost does not meet industrial temperature levels.
Does ASTM approve products?
No. Only certification bodies like BPI approve products.
Conclusion
ASTM D6400 is one of the most important standards for compostable plastics in the United States. It tells us how to test plastics for safe industrial composting. It protects soil, supports composting facilities, and helps businesses make honest claims.
If you use compostable bags or packaging, understanding this standard helps you choose products that truly break down—not just those with green labels.
