Last updated: 2026-09-08

Compostable vs Biodegradable Bags: What’s the Real Difference?

If a supplier tells you their bags are “biodegradable,” they have told you almost nothing. If they tell you the bags are “compostable” and can hand you a certificate number, you have something you can defend to a regulator, a retail buyer, and your own customers.

That gap — between a word with no deadline and a word with a test behind it — is where most greenwashing in this category lives.

But there is a second gap, and it catches buyers who have already learned the first lesson. Compostable bags are a subset of biodegradable ones, and every compostable bag carries a certificate. Yet a certified industrial-compostable bag dropped into a backyard heap can sit there for years, largely intact, looking exactly like the plastic it was meant to replace. The certificate is real. The bag is real. The disposal route was wrong.

This guide covers both gaps: what the words mean, and what actually happens to the bag afterward.

The One-Sentence Answer

Biodegradable means a material can be broken down by microorganisms. Compostable means it breaks down under specific conditions, within a defined timeframe, leaving no toxic residue — and someone tested it to prove that.

Everything compostable is biodegradable. Almost nothing that is merely biodegradable meets the compostable bar.

Biodegradable: A Claim With No Deadline

The word describes a process, not a result. Technically, a steel shipping container biodegrades — given enough centuries. Without a standard attached, a biodegradable claim carries:

• No defined timeframe. Months or hundreds of years both qualify.
• No temperature requirement. A claim tested at 58°C says nothing about a backyard pile at 20°C.
• No residue limit. Fragmenting into microplastics and calling it degradation is, technically, still degradation.

There is a second trap underneath this one. “Biodegradable” says nothing about what the bag is made from. Bio-based bags come from renewable feedstock like corn or cassava starch. Fossil-based bags are conventional petrochemical plastic with additives — and those are legally sold as biodegradable in many markets. The claim describes the end of life, not the beginning. Our modified raw material page breaks down what actually goes into the resin.

Then there is oxo-degradable, which deserves its own warning. These are conventional plastics with additives that make them fragment faster. They do not biodegrade in any meaningful sense — they shatter into smaller plastic pieces sooner. Several jurisdictions have moved to prohibit them outright. If a supplier offers you “oxo-biodegradable,” treat it as a compliance liability, not an eco-option.

The criticism worth taking seriously here comes from people who are not trying to sell you anything. Eartheasy, a retailer that has sold reusable goods for two decades, argues that most bioplastics do not break down in home composting or landfill, that they contaminate conventional recycling streams, and that many contain a substantial share of conventional plastic anyway. They are right about the first two points when the claim is “biodegradable.” The response is not to argue — it is to buy certified compostable, match it to the disposal route, and verify the certificate.

Compostable: A Claim With a Test Behind It

Compostable flips every one of those three blanks into a number.

Requirement	What it means in practice
Timeframe	Disintegration within a defined window — commonly 12 weeks for industrial, 6 months for home
Conditions	A specified temperature and microbial environment — industrial or home
Residue	No toxic residue, no microplastics; ecotoxicity testing on the resulting compost

Which standard applies depends on where the bag will be sold and disposed of:

• ASTM D6400 — the US benchmark, administered in practice by BPI. Industrial composting.
• EN 13432 — the European equivalent, marked by the Seedling logo.
• AS 4736 (industrial) and AS 5810 (home) — Australia, via ABA. Both Australian standards add an earthworm toxicity test that ASTM D6400 and EN 13432 do not require.
• OK Compost and OK Compost Home — TÜV Austria. The “Home” variant is the only meaningful backyard-compostable credential.
• NF T51-800 — the French home-composting standard, one of the bases for OK Compost Home.

Here is the part that catches experienced buyers. Certification applies to the finished product — the resin, the ink, the adhesive, the drawstring, and the thickness — not to the pellet the resin came from. A supplier who says “PLA is compostable” has told you about a polymer, not about a bag. Ask for the certificate that matches the exact SKU you are buying, then look the number up on the issuing body’s own registry.

How a Bag Actually Breaks Down: Hydrolysis First, Microbes Second

This is the part most comparison articles skip, and it explains everything that follows.

Breakdown is not one process. It is two, and they must happen in this order:

1. Hydrolysis. Water molecules attack the ester bonds holding the polymer chains together, cutting them into shorter fragments. For PLA and PBAT, this needs heat and moisture. PLA in particular requires sustained temperatures above roughly 55–60°C to hydrolyse at any meaningful rate. Below that threshold, the reaction slows to near zero.

2. Microbial digestion. Once the chains are short enough, bacteria and fungi metabolise the fragments into carbon dioxide, water, and biomass.

The constraint is the order: microbes cannot digest intact long-chain polymers. Hydrolysis has to happen first. And hydrolysis is temperature-dependent.

That single dependency is why conditions are decisive rather than incidental. It is not that a bag breaks down slower in a cool pile — it is that the first step essentially does not start.

Not All Compostable Resins Behave the Same

The material decides the temperature threshold, and the thresholds are far apart:

Material	Source	Typical behaviour
PLA	Fermented plant sugars (corn)	Fast in industrial composting; very slow in home compost — often years, sometimes effectively never within a useful timeframe
PBAT	Petroleum co-polymer, genuinely biodegradable	Flexible; blended with PLA or starch. Composts under industrial conditions, slow in home
Starch blends	Potato, corn, or cassava starch	Bonds are more vulnerable to water attack at lower temperatures — viable for home composting
PHA	Produced by microbes	Broader compostability; can break down in home compost within months
Cellulose films	Plant fibre	Generally home compostable in cool piles
Polyethylene (PE)	Petroleum	Does not hydrolyse. Fragments into microplastics but never fully mineralises

Two things follow from this table. First, “compostable” is not a material — it is a performance claim that depends on the resin and the route. Second, being bio-based does not make a bag fast to compost. PLA is plant-derived and is among the slowest materials in a backyard heap.

Industrial vs Home Composting: The Gap That Decides Everything

This is where most sourcing mistakes happen.

	Industrial composting	Home composting
Temperature	Sustained 50–70°C, actively managed	Ambient, typically 20–35°C, seasonal
Management	Controlled aeration, moisture, regular turning	Whatever the owner does
Typical window	Fragments within 6–12 weeks; fully mineralises within roughly 3–6 months	Home-certified products: 6–12 months. Industrial-certified products: unpredictable, often years
Certification	ASTM D6400, EN 13432, AS 4736	OK Compost Home, AS 5810, NF T51-800
What it handles	PLA, PBAT, starch blends, and food-contaminated packaging	Starch blends, PHA, cellulose — and only products with home certification

The practical consequence: a bag certified to EN 13432 or ASTM D6400 is certified for industrial conditions only. Putting it in a home bin is not a slower version of the same outcome. For PLA-based bags at ambient temperature, the hydrolysis step barely starts. Home-compostable bags cost more because the resin has to be formulated to break down without industrial heat — that is a material difference, not a marketing tier.

Where does industrial composting actually exist? Coverage varies enormously by municipality. Before specifying a bag, confirm what your market’s organics programme accepts — some accept certified compostable liners, some explicitly do not, and a contaminated load can be rejected at the gate regardless of what the bag is certified to.

Where the Bag Ends Up: Four Destinations, Four Outcomes

The same certified bag has four very different fates. This is the part buyers should model before committing to a spec.

Destination	What happens	Verdict
Industrial composting	Heat, oxygen, and microbial density are present. The bag fragments and mineralises within the tested window, and food-contaminated bags are an asset rather than a problem	✅ The intended route
Certified home composting	Works if the bag carries home certification. Without it, it persists	✅ With the right certification
Landfill	Anaerobic, no light, no oxygen. Degradation largely stalls. Any breakdown that does occur can release methane — a greenhouse gas far more potent than CO₂	⚠️ Honestly: no better than conventional plastic, and arguably worse on climate
Recycling stream	Compostable film is a contaminant in PE recycling. It does not belong here	❌ Never

The landfill row deserves emphasis because it is the one most marketing avoids. A compostable bag buried in landfill does not deliver its environmental benefit. It is not that the bag is bad — it is that the route determines the outcome. If your market has no organics collection, a compostable spec still reduces fossil content and persistent microplastic load, but you should not build a marketing claim on end-of-life compostability you cannot evidence.

This is also why compostable trash bags specified for food-waste programmes look different from bags specified for dry retail carry. Same material family, different certification, different end-of-life assumption.

What Compostable Actually Buys You — and What It Doesn’t

The environmental case, stated honestly

When the route exists, certified compostable bags deliver:

• Organics diversion. Food waste and its packaging go to compost instead of landfill, which is the single largest lever in most municipal waste strategies.
• Fossil displacement. PBAT aside, the resin is substantially plant-derived, reducing dependence on virgin petrochemical feedstock.
• No persistent microplastics. Certified compostable film mineralises. Conventional PE fragments into microplastics that persist indefinitely — it never fully breaks down; it just gets smaller.
• Soil return. The output is compost, not residue. Ecotoxicity testing is a certification requirement, not an optional extra.

The commercial case

Beyond the environmental argument, there are four reasons B2B buyers switch:

1. Regulatory risk. Single-use plastic restrictions keep tightening across multiple markets. A certified spec removes the scramble when a rule changes and removes the exposure of an unsubstantiated claim.
2. Channel access. Some retail programmes and municipal contracts require certified compostable packaging. Without the certificate, you are not in the conversation.
3. Brand differentiation. Packaging is the one part of your sustainability story the customer physically holds. It is more tangible than a webpage.
4. ESG reporting. Packaging is a visible, reportable metric in most frameworks — and one that independent certification makes defensible.

What it does not buy you

Let us be direct about the limits, because overselling here is how buyers get burned:

• Unit cost is higher. Compostable resin costs more than conventional PE. The premium moves with resin grade, thickness, certification scope, and order volume.
• Infrastructure is not guaranteed. If your market has no organics collection, the end-of-life benefit largely disappears.
• The certificate is not the whole product. It certifies the SKU as tested, not the supply chain behind it.

If you are sourcing at volume, our compostable bag manufacturing and supply team can quote against your exact market, SKU, and disposal route — which is the only way a cost comparison means anything.

Side-by-Side: 5 Differences That Decide Compliance

Dimension	Biodegradable	Compostable
Timeframe	No defined limit — “eventually”	Defined window, tested and certified
Conditions	Unspecified	Specified: industrial (50–70°C) or home (ambient)
Residue	May leave microplastics or additives	Must leave no toxic residue; ecotoxicity tested
Verification	No mandatory testing in most markets	Independent third-party certification, traceable number
Disposal route	Usually general waste	Industrial composting or certified home composting

The fifth row is the one that decides your specification. A compostable bag is only better than a conventional one if the infrastructure exists to process it.

How to Read the Certification Logos

Four marks cover most commercial markets:

Logo	Issuer	Standard	Covers
BPI (circular mark)	Biodegradable Products Institute	ASTM D6400	US industrial composting
Seedling	European Bioplastics, licensed via bodies including DIN CERTCO	EN 13432	EU industrial composting
OK Compost / OK Compost Home	TÜV Austria	EN 13432 / home variant	EU; “Home” for backyard
ABA (with AS number)	Australasian Bioplastics Association	AS 4736 / AS 5810	Australia, industrial / home

For the full standard-by-standard breakdown, see compostable bag certification.

Two habits protect you more than memorising logos. First, check the number, not the artwork — our walkthrough on how to identify compostable bags shows what valid documentation looks like and where to verify it. Second, match the standard to the destination, not to where the bag was made. A bag certified for EU industrial composting is not automatically accepted by a US municipal programme, and our certifications page lists the ones we hold.

Regulators have also started policing the language itself. Advertising standards bodies in several markets have ruled against “compostable” claims where consumers reasonably understood them to mean home compostable and the product was not. If your packaging says compostable, say which kind — and don’t let the artwork imply more than the certificate covers.

What People Actually Experience (and What to Do About It)

Search any zero-waste community, and you will find the same complaint in different words: I put a compostable bag in my bin months ago, and it is still there.

It is worth understanding why, because the answer is seldom “the bag was fake”:

Cause	Why it stalls
Wrong certification for the route	An industrially certified bag in a home pile. This is the most common cause by a wide margin
Pile never gets hot enough	Ambient temperature is below the resin’s hydrolysis threshold
Too dry, or too wet	Hydrolysis needs moisture; waterlogged piles go anaerobic and slow further
Bag is too thick	Thicker film has less surface area relative to mass and takes longer
Not enough oxygen	Aerobic breakdown needs airflow; compacted piles stall

What helps in practice:

• Cut the bag into strips before adding it. More surface area, faster attack.
• Match the bag to the bin. Home-certified bags for home bins; industrial-certified bags for municipal organics collection.
• No home bin? Look for community composting drop-offs, council organics programmes, or small-space options — worm bins, Bokashi, or an electric kitchen composter. If landfill is genuinely the only option, that changes which bag you should buy, and it is better to know that upfront.
• Check the certificate for the word “home.” A generic “compostable” mark without home certification means industrial only.

One more specification note that saves warranty claims: compostable resin ages on the shelf. PLA/PBAT blends lose mechanical properties over roughly 12 months in hot or humid storage, and bags start tearing. We cover storage conditions and how to check the age of a batch in the shelf life of compostable bags. Store cool and dry, and rotate stock.

Which One Should Your Business Actually Buy?

Start with the question nobody asks early enough: where will this bag end up, and who collects it?

• Municipal or commercial organics collection exists → industrial-compostable certification (BPI / EN 13432 / AS 4736). This covers most food-service, grocery, and food-waste liner applications.
• No collection; customers compost at home → home-compostable certification (OK Compost Home / AS 5810 / NF T51-800). Slower to break down, but it degrades without industrial heat.
• Neither exists → say so honestly. Compostable still reduces fossil content and persistent microplastic load, but the end-of-life story is weaker, and you should not build a marketing claim on it.

On cost: the useful comparison is per-unit landed cost against your current spec — including the compliance risk you are removing. Rather than quote a number that will be stale in a quarter, request a quote against your actual market, volume, and disposal route.

The Bottom Line

The distinction is not academic — it decides whether your packaging claim survives contact with a regulator, a retail compliance team, or a customer’s compost bin.

Three things matter, in this order:

1. Buy the tested claim, not the adjective. “Biodegradable” has no deadline, no temperature, and no residue limit. “Compostable to EN 13432, certificate number attached” has all three.
2. Match the certification to the disposal route. This is the step that most buyers skip, and it is where the money is lost. An industrial-certified bag in a home bin is not a slower outcome — for PLA-based resins, the chemistry barely starts.
3. Verify the number, not the artwork. Certification applies to the finished product. Look the certificate up on the issuing body’s registry and confirm it covers the SKU you are buying.

Get those three right and the bag does what the label says. Get the second one wrong, and you have paid a premium for a bag that behaves like the plastic it replaced.

FAQ

About ShinHigh Bio

ShinHigh Bio (Dongguan Xinhai Environment-Friendly Materials Co., Ltd.) has compounded and converted compostable materials in Dongguan since 2000. We run our own resin compounding — 10 underwater pelletising lines and 30,000 tonnes of annual capacity — which is why we can formulate for a specific disposal route rather than selling one general-purpose film. Two grades cover most applications: XH-918 (PBAT/PLA/cornstarch), certified for home composting, and SH-133 (PBAT/PLA) for general compostable use.

Holding both industrial and home compostable certifications matters commercially, because the two serve different buyers: a customer supplying a market with municipal organics collection needs EN 13432 or ASTM D6400, while a brand selling to households that compost at home needs OK Compost Home or AS 5810. Ours are certified by TÜV Austria, BPI, DIN CERTCO, and ABA, with third-party testing by OWS.

We supply OEM and ODM, and provide the extrusion parameters — screw temperature and speed — that converters need to run these resins without guessing. Free samples available.

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