Biodegradable and compostable are not the same thing

Biodegradable means a material will break down into natural substances — carbon dioxide, water, and biomass — when exposed to microorganisms in the environment. Compostable means it will break down into those same substances, but within a specific timeframe (usually 180 days) and in a controlled composting environment, leaving no toxic residue.

The key difference: biodegradable can happen anywhere — a landfill, the ocean, your backyard — and may take years or decades. Compostable requires the right conditions: the heat, moisture, oxygen, and microbial activity found in an active compost pile or industrial facility. A material can be biodegradable but not compostable. The reverse is rarely true.

This matters because "biodegradable" on a label often means nothing enforceable. There is no federal standard for how fast something must break down or under what conditions. "Compostable" usually means the product has been tested against a standard — either ASTM D6400 (industrial compost) or ASTM D6868 (home compost) in the United States.

Key Takeaways

  • Biodegradable materials break down eventually in any environment; compostable materials break down in 180 days or less in a compost pile or facility with no toxic residue left behind.
  • A product labeled biodegradable may take years to decompose in a landfill and offers no may provide of how long the process takes.
  • Compostable products are tested against a standard and will break down in home or industrial compost, but most require industrial heat and conditions to do so.
  • Putting a "compostable" item in a landfill defeats its purpose — it will not compost without the right environment, and it may release methane as it slowly breaks down.
  • Check the label for "certified compostable" and the standard it meets (ASTM D6400 for industrial, ASTM D6868 for home) rather than relying on the word alone.

Why "biodegradable" is often a marketing term with no teeth

The word biodegradable appears on everything from plastic bags to food packaging, but it is not regulated by the Federal Trade Commission in a way that sets a important date or a standard environment. A manufacturer can claim a product is biodegradable if it will eventually break down — even if that takes 50 years in a landfill where little oxygen or microbial activity exists.

Plastic bags labeled "biodegradable" are a common example. They may fragment into smaller pieces over time, but fragmentation is not the same as biodegradation. The pieces persist in the environment for decades, harming wildlife and entering waterways. The label gives the impression of environmental responsibility without requiring the product to actually disappear in any reasonable timeframe.

Some states have moved to restrict the use of the word biodegradable on packaging without a specific claim about timeframe and conditions. California, for instance, bans claims that a product is biodegradable unless the manufacturer can prove it will completely break down within a set period under normal environmental conditions — a standard almost no plastic meets.

What "compostable" actually requires

Compostable products are tested in a laboratory against one of two standards. ASTM D6400 is the industrial standard: the product must break down into carbon dioxide, water, and biomass within 180 days in a commercial composting facility, where temperatures reach 130 to 160 degrees Fahrenheit and conditions are carefully controlled. ASTM D6868 is the home compost standard, which uses lower temperatures (around 68 degrees Fahrenheit) and a longer timeframe (one year) to reflect backyard conditions.

Most products labeled "compostable" meet the industrial standard, not the home standard. This means they will break down in a municipal composting facility or a large-scale operation, but not reliably in a home compost bin. The label should say which standard the product meets; if it does not, the manufacturer has not had it tested.

Compostable does not mean the product will break down in a landfill. Landfills are anaerobic — they lack oxygen — so even certified compostable items will sit intact for years and eventually release methane as they slowly decompose. Putting a compostable product in the trash defeats the entire purpose.

Industrial versus home compostable: where your item actually goes

If a product says "compostable" without specifying home or industrial, assume it needs industrial conditions. Industrial composting facilities have the equipment and informed to reach the high temperatures and moisture levels required. They also monitor the process and can handle materials that break down slowly or incompletely.

Home compostable products are rarer and more expensive because they must work in a backyard pile where you cannot control temperature, moisture, or aeration as precisely. If you have an active compost bin and the label says "home compostable" or "ASTM D6868," you can add it. If the label says only "compostable" or "ASTM D6400," you will need to take it to a municipal facility or a commercial composting service.

Many communities do not have municipal composting programs, which means a certified compostable product may have nowhere to go. Check your local waste management website or call your city to find out whether your area accepts compostable items and where to drop them off.

Common materials and what they actually are

Compostable food containers and utensils are usually made from polylactic acid (PLA), a plastic derived from corn starch or sugarcane. PLA is certified compostable under ASTM D6400 but requires industrial heat to break down. It will not compost in a home bin and will persist in a landfill. Some facilities that accept compostable items do not accept PLA because it can contaminate their process if it does not fully break down.

Paper and cardboard are naturally biodegradable and will break down in a home compost pile, a landfill, or the environment, though the timeframe varies. They do not need to be certified compostable because the term is redundant — they will decompose on their own. Waxed or plastic-coated paper, however, is not compostable and should not go in your bin.

Mushroom-based packaging and other mycelium products are newer and genuinely home compostable. They break down in a backyard pile within weeks to a few months. These are less common and more expensive than PLA, but they offer a real alternative if you compost at home.

How to read a compostable label correctly

Look for the word "certified" and the standard it meets. A label that says "certified compostable ASTM D6400" tells you the product has been tested and will break down in an industrial facility. A label that says only "compostable" or "biodegradable" without a standard or certification number is a marketing claim with no enforcement behind it.

Some labels include a logo from a third-party certifier like the Biodegradable Products Institute (BPI) or the European standard EN 13432. These logos mean the product has been independently tested and verified. If you see a logo, you can look it up on the certifier's website to confirm what conditions the product requires.

If the label does not mention a standard or certifier, treat it as marketing language. The product may break down eventually, but you have no may provide of how long it will take or what conditions it needs. In that case, compost it only if you are confident it is paper, cardboard, food waste, or another material you know will decompose.

What happens if you compost something that is not actually compostable

If you put a non-compostable item in your home compost bin, it will sit there for years without breaking down. Plastic fragments, synthetic fibers, and treated materials do not decompose in a home pile. When you use the finished compost in your garden, these pieces remain and can harm soil structure and plant roots.

In a municipal composting facility, non-compostable items cause bigger problems. They can jam equipment, contaminate batches, and end up in the finished compost, which is then spread on farms and gardens. Facilities that accept compostable items often ask residents to remove any plastic bags and to rinse containers before dropping them off — not because the containers are compostable, but to prevent contamination.

If you are unsure whether something is compostable, check the label or the manufacturer's website. If there is no clear answer, put it in the recycling bin or the trash instead of risking contamination.

Frequently Asked Questions

Can I put compostable bags in my home compost bin?

Only if the label says "home compostable" or "ASTM D6868." Most compostable bags are made from PLA and require industrial heat to break down. In a home bin, they will sit intact for years. If your bag does not specify home compost, take it to a municipal facility or leave it out of your bin.

Is paper compostable?

Yes. Plain paper, cardboard, and paper bags break down naturally in a home compost pile within a few months. Waxed, plastic-coated, or glossy paper should not go in compost because the coating does not decompose. Shred paper into small pieces to speed up the process.

What is the difference between compostable and recyclable?

Recyclable means the material can be processed into a new product. Compostable means it will break down into soil. A product can be one, both, or neither. PLA containers are compostable but not widely recyclable. Aluminum is recyclable but not compostable. Check your local program to see which items go where.

If something is compostable, why can't I just throw it in the trash?

Landfills lack oxygen and moisture, so compostable items break down very slowly and release methane, a potent greenhouse gas. Composting requires the right conditions — heat, oxygen, and active microorganisms — that a landfill does not provide. Throwing compostable items in the trash wastes their environmental benefit.

How do I know if my area has composting programs?

Call your city or county waste management department, or visit their website. Search for "composting near me" or "municipal composting [your city]." Some areas offer curbside compost pickup; others have drop-off locations. If your area has no program, you can start a home compost bin or check whether local farms or gardens accept compostable items.