Compostable VS Biodegradable – What Is The Difference And Why Should You Care?

Compostable and biodegradable are 2 words we often end up using interchangeably as we discuss recycling. However, the truth is there is a huge difference between them. In order to better understand the compostable vs biodegradable debate, we should first discuss what the terms actually mean. Then, we will highlight why it is so important to make the correct choice.

Defining Biodegradable

The term “biodegradable” is featured on several products we regularly buy, like shampoos or soap. What it means is that the material is going to safely and quickly break down into compounds that are mostly harmless.

What will make the substance biodegradable?

In most cases, everything that is natural mineral-based, animal-based, or plant-based is biodegradable. But, breaking down can happen at considerably different rates. This is based on the product’s original material and the amount of processing it went through.

The ASTM (American Society for Testing and Materials) dictates that biodegradables can be any products that will undergo a degradation process due to naturally occurring microorganisms. This includes things like algae, fungi, and bacteria.

A biodegradable product is going to break down much faster than a non-biodegradable product (for instance, plastic). Most people assume biodegradable automatically means plants-based, but this is not actually the case. Other examples of biodegradable products include bags, boxes, and papers. Practically anything created that can break down slowly until it reaches the microscopic level is most likely biodegradable.

Defining Compostable

We can define “compostable” as a product that can break down into completely natural elements when faced with a compost environment. Since it will break down right into natural elements, there is no harm that will come to the environment during the process. Usually, breaking down compostable materials takes around 90 days.

According to the ASTM, compostable materials can be anything that will undergo a degradation process through biological processes as composting happens, with the process yielding inorganic compounds, biomass, water, and CO2. This needs to happen at consistent rates and no toxic or distinguishable residue remains behind.

The Difference Between Compostable And Biodegradable

When looking at how the terms are defined, it is very easy to understand why they are confused. However, there is a big difference we should be aware of. All the compostable materials are biodegradable materials. The opposite does not apply.

Biodegradable materials will return to nature. They will completely disappear but some metal residue is left behind. With compostable materials, humus is created. This humus is very rich in nutrients and can be used for helping plants grow.

To put it as simple as possible, a compostable product is a biodegradable product, but it does have a very useful extra benefit. As it breaks down, valuable nutrients are released into the soil. This helps plants and trees grow.

Why Is It So Important To Know This Difference?

Compostable products are organic matter that will break down, with the end of the process being highly beneficial for nature since it will improve soil health and provide fertilizer. With biodegradable items, we only have the advantage that it will not hurt nature. With compostable products, they actually help nature.

Compostable items will not leave any toxic residue behind. This is because they are organic. Biodegradable products are not like compostable products. They can easily take years to fully break down. Also, in some situations, toxic waste can be left behind.

As a very simple example to understand, plastics that are plant-based do often have the biodegradable label. They do break down faster and easier than plastic. They are also much safer but when the correct factors are not a reality, breaking down biodegradable plastics will take as much time as the regular plastics.

We can say that the process of biodegrading is all about being faced with the correct amount of temperature and moisture. With compostable products, you do not need to worry about external environmental factors since they will not be relevant.

Final Thoughts

If we are to talk about recycling, the confusion created by labels with compostable and biodegradable on them is very high. The compost industry is actually the one that is mostly careful about the proper use and is working hard to create specific standards to be used. It is very important to properly label products as being either compostable or biodegradable.


Amelia Robinson is a lover of plants and gardens, as well as an educator on this topic. It’s her goal to make sure that you get the chance to learn what you need to about gardening to succeed with your own home garden at the blog You’re not going to find just a collection of basic articles about gardening here. Instead, she wants to answer the difficult questions for you. She tweets at @robinsonplants

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