How Biodegradable Is Cardboard?

Cardboard is one of the most ubiquitous packaging materials in modern society. Its low cost and ease of manufacture have made it a go-to choice for everything from product packaging to moving boxes. But how biodegradable is cardboard, really? If you’re short on time, here’s a quick answer to your question: Cardboard is generally quite biodegradable, breaking down in a matter of months when exposed to the elements. However, some factors can affect how quickly it decomposes. Read on for a more in-depth look at the biodegradability of cardboard.

In this comprehensive article, we’ll explore what cardboard is made of, look at how it breaks down, discuss the factors that affect its decomposition rate, and provide tips for proper cardboard disposal and recycling.

What Is Cardboard Made Of?

Cardboard, as its name suggests, is made primarily from wood fibers. These fibers come from a variety of sources, including recycled paper and wood pulp from sustainably managed forests. The process of making cardboard involves breaking down these fibers and then reassembling them into a sturdy and versatile material.

Cellulose fibers

The main component of cardboard is cellulose, a complex carbohydrate found in plant cell walls. Cellulose fibers give cardboard its strength and durability. These fibers are extracted from trees and plants through a process called pulping. Once the fibers are separated from other materials, they are mixed together to form a pulp, which is then shaped into the desired form.

Binders and fillers

In addition to cellulose fibers, binders and fillers are added to the cardboard mixture. Binders, such as starch or glue, help hold the fibers together and improve the overall strength of the material. Fillers, such as clay or calcium carbonate, are added to improve the smoothness and printing properties of the cardboard.


To enhance the performance of cardboard, various coatings can be applied to its surface. These coatings serve different purposes, such as making the cardboard water-resistant, improving its printing capabilities, or increasing its resistance to grease and oils. Common coatings include wax, polyethylene, and mineral oil.

It’s important to note that while cardboard is primarily made from natural materials, the addition of binders, fillers, and coatings may affect its biodegradability. Some coatings, for example, may slow down the decomposition process. However, advancements in technology have led to the development of biodegradable coatings that are more environmentally friendly.

How Does Cardboard Biodegrade?

Cardboard is known for being a biodegradable material, meaning it can naturally break down and decompose over time. But how exactly does cardboard biodegrade? Let’s take a closer look.

Role of microorganisms

One of the key factors in the biodegradation of cardboard is the role of microorganisms. These tiny living organisms, such as bacteria and fungi, play a crucial role in breaking down the cellulose fibers found in cardboard. They secrete enzymes that help break down the complex structure of cellulose into simpler compounds that can be easily digested.

This process is similar to how microorganisms help decompose other organic materials, such as leaves and food waste. The presence of moisture and oxygen also contributes to the growth and activity of these microorganisms, accelerating the biodegradation process.

Cellulose breakdown process

Cellulose is the main component of cardboard and is made up of long chains of glucose molecules. Breaking down these chains into smaller units allows microorganisms to consume and digest them. The enzymatic breakdown of cellulose starts with the degradation of the outer layers, gradually working its way toward the inner layers of the cardboard.

As the cellulose fibers break down, they release carbon dioxide and water as byproducts. These byproducts are harmless and contribute to the natural carbon cycle in the environment.

Timeline for biodegradation

The timeline for cardboard biodegradation can vary depending on various factors, such as environmental conditions and the thickness of the cardboard. In general, it can take anywhere from a few weeks to a few months for cardboard to completely biodegrade.

However, it’s important to note that not all cardboard biodegrades at the same rate. Factors such as the type of cardboard (corrugated or paperboard) and the presence of coatings or laminations can affect the biodegradation process.

It’s also worth mentioning that while cardboard is biodegradable, it still requires proper disposal methods to ensure it breaks down efficiently. Recycling cardboard is an excellent way to reduce waste and promote sustainability. By recycling cardboard, we can save energy and resources that would otherwise be used to produce new cardboard.

So, the next time you’re wondering about the biodegradability of cardboard, rest assured that it is indeed a sustainable material that can break down naturally over time.

Factors Affecting Cardboard’s Decomposition Rate

When it comes to the biodegradability of cardboard, several factors come into play that affect its decomposition rate. Understanding these factors can help us make informed decisions about how to properly dispose of cardboard and reduce its impact on the environment.

Exposure to air, light, and moisture

The decomposition of cardboard heavily relies on the presence of air, light, and moisture. These elements provide the necessary conditions for microorganisms to break down the cardboard fibers. When cardboard is exposed to these factors, it can decompose relatively quickly, especially in environments with high humidity. However, if cardboard is stored in dry or sealed conditions, its decomposition rate can be significantly slower.

Presence of microorganisms

Microorganisms play a crucial role in breaking down cardboard. Bacteria, fungi, and other microorganisms produce enzymes that can digest the cellulose fibers in cardboard. The presence of a diverse and active microbial community can accelerate the decomposition process. Therefore, the availability of these microorganisms, which can vary depending on the environment, can impact how quickly cardboard decomposes.

Type of cardboard

The type of cardboard also affects its decomposition rate. Cardboard made from recycled fibers tends to decompose faster compared to cardboard made from virgin fibers. This is because recycled cardboard fibers have already gone through a degradation process during the recycling stage, making them more susceptible to further decomposition. Additionally, the thickness and density of the cardboard can also influence its decomposition rate, with thinner and less dense cardboard decomposing more rapidly.


Contaminants present in cardboard, such as inks, dyes, and adhesives, can affect its biodegradability. Some of these contaminants may contain chemicals that hinder the decomposition process or introduce toxins into the environment. Therefore, it is important to consider the composition of the cardboard and its potential impact on the environment when assessing its biodegradability.

For more information on the biodegradability of cardboard, you can visit or which provide valuable resources and guidelines on proper waste management practices.

Proper Cardboard Disposal and Recycling

When it comes to the disposal and recycling of cardboard, it is important to do it properly to minimize environmental impact. Cardboard is a highly recyclable material, and recycling it not only helps reduce waste but also conserves valuable resources. Here are some ways you can dispose of cardboard responsibly:

Curbside pickup and drop-off centers

One of the most convenient ways to recycle cardboard is through curbside pickup or drop-off centers. Many municipalities have recycling programs in place that include cardboard collection. All you need to do is flatten your cardboard boxes, tie them up, and leave them by the curb or take them to the designated drop-off location. This ensures that the cardboard will be properly recycled and turned into new products.

Industrial recycling

Another option for cardboard recycling is through industrial recycling facilities. These facilities are equipped with specialized machinery that can handle large volumes of cardboard. They process the cardboard by shredding it into small pieces and then turning it into pulp, which is used to make new cardboard products. Industrial recycling is particularly effective for businesses and organizations that generate significant amounts of cardboard waste.


Did you know that cardboard can also be composted? If you have a composting system at home or access to a composting facility, you can add cardboard to your compost pile. Cardboard is considered a brown material in composting, providing carbon and helping to balance the ratio of carbon to nitrogen. Just make sure to shred the cardboard into smaller pieces before adding it to the compost to help it break down faster.

Landfill disposal

While recycling and composting are the preferred methods for cardboard disposal, sometimes it is unavoidable to dispose of cardboard in the landfill. However, it is important to note that cardboard is biodegradable and will break down over time in a landfill. Nevertheless, it is always best to explore recycling and composting options first to minimize the amount of waste sent to landfills.

For more information on proper cardboard disposal and recycling, you can visit Recycle Across America or U.S. Environmental Protection Agency.


As we’ve seen, cardboard is generally biodegradable within months when exposed to the elements. While factors like cardboard type, contaminants, and environmental conditions can affect the rate of decomposition, cardboard will break down much faster than plastics and other less-sustainable packaging options. By disposing of cardboard properly through recycling, composting, or landfills, we can allow it to return to the earth responsibly. With a basic understanding of cardboard’s biodegradability, we as consumers can make informed choices about cardboard usage and make sure this ubiquitous material doesn’t overstay its welcome in the environment.

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