Most paper is compostable, but not all of it

Plain paper — newspaper, cardboard, paper bags, office paper — breaks down in a compost bin or pile within a few months to a year, depending on how wet and warm your pile stays. The fibres are already broken down by the manufacturing process, so microbes and fungi can work through them quickly. What stops paper from composting is what has been added to it: plastic coating, ink that contains heavy metals, glossy finish, or a waterproof layer.

The question is not whether paper can compost, but whether what is on the paper will compost alongside it. A newspaper will break down. Newspaper with a plastic film laminate will not. The coating stays behind as a contaminant.

Key Takeaways

  • Uncoated paper, cardboard, and newsprint compost within months and add carbon to your pile.
  • Glossy paper, plastic-coated paper, and paper with synthetic inks should not go in compost because the coating or ink does not break down.
  • Paper with food residue on it (pizza boxes, takeout containers) can compost if the paper itself is uncoated, but grease may slow decomposition.
  • Shredded paper composts faster than whole sheets because it has more surface area for microbes to attack.
  • Coloured cardboard and kraft paper are safe to compost unless they have a plastic or wax layer on the inside.

Paper that is safe to add to compost

Newspaper is one of the fastest-composting papers. It has no coating and the ink is soy-based or mineral-based in most modern papers, which breaks down without leaving toxic residue. Shred it or tear it into strips so it does not mat down and block air flow.

Cardboard — the kind used for shipping boxes and product packaging — is uncoated and compostable. Remove tape, staples, and plastic packing materials first. Corrugated cardboard (the wavy kind) breaks down slower than flat cardboard because air pockets trap moisture, but it will still decompose. Flatten it and cut it into pieces roughly 6 inches across so it mixes into the pile instead of sitting as a solid block.

Paper bags (grocery bags, kraft paper bags) are uncoated and compostable. Shred them or crumple them to speed breakdown. Paper bags with plastic windows or plastic handles should have those parts removed first.

Office paper, printer paper, and envelopes (without plastic windows) compost, though they break down slower than newspaper because they are denser. Shredding helps. Envelopes with plastic address windows should have the window removed.

Paper towels and napkins compost if they are not bleached white. Most are, but the bleach breaks down in the compost environment and does not persist as a contaminant. Avoid paper towels that have been in contact with meat or dairy unless your compost pile reaches 140°F or higher, because cool piles may not kill pathogens.

Paper products that should not go in compost

Glossy paper — magazines, brochures, product packaging with a shiny finish — has a plastic or wax coating that does not break down. The paper underneath will compost, but the coating will remain as microplastics or wax fragments in your finished compost. Throw these in recycling or trash instead.

Plastic-coated paper includes takeout containers with a waterproof interior, frozen food boxes, and some paper cups. The plastic layer keeps the paper from touching moisture and microbes, so neither the paper nor the plastic decomposes. Check the inside of the container: if it feels slick or has a visible plastic film, do not compost it.

Wax-coated paper (deli paper, some baking parchment, cheese wrapping) does not compost because wax is a petroleum product that microbes cannot digest. Some newer products use plant-based wax, but most still do not break down in a home compost environment.

Coloured or printed paper with synthetic inks — especially if the ink is bright or metallic — may contain heavy metals like cadmium or lead. Newspaper ink is safe, but commercial printing inks vary. When in doubt, keep brightly coloured or metallic-printed paper out of compost.

Paper with food residue can go in compost if the paper itself is uncoated, but grease and oil slow decomposition and can create odour problems. Pizza boxes are a common question: the cardboard is compostable, but the grease from the pizza may prevent the paper from breaking down evenly. If the grease is light, tear out the worst-affected pieces and compost the rest. If the box is heavily oiled, throw it in trash or recycling.

How to prepare paper for faster composting

Shredding or tearing paper into pieces 2 to 4 inches across increases the surface area that microbes can access, which speeds decomposition by weeks or months. A whole sheet of newspaper may take 6 months; shredded newspaper may break down in 6 to 8 weeks.

Wet the paper as you add it to the pile. Dry paper takes longer to break down because microbes need moisture to work. If your pile is already damp, you do not need to add water, but if it is dry, spray the paper with a hose or soak it before adding it to the compost.

Mix paper with nitrogen-rich materials like food scraps, grass clippings, or manure. Paper is carbon-heavy and breaks down faster when it has nitrogen to feed the microbes. A ratio of roughly 3 parts carbon (paper, leaves, wood chips) to 1 part nitrogen (food scraps, fresh grass) keeps decomposition moving.

What happens to paper that should not be composted

If you accidentally add glossy paper or plastic-coated paper to your compost pile, the paper will eventually break down, but the coating will not. When you use the finished compost in your garden, the coating fragments will remain in the soil. Over time, these fragments accumulate and can affect soil structure and water retention.

Plastic-coated paper is the most problematic because it can fragment into microplastics that persist in soil for years. Glossy paper leaves wax or plastic particles that are less harmful but still undesirable. If you notice shiny fragments in your finished compost, sift them out before using the compost on food crops.

Frequently Asked Questions

Can I compost paper with ink on it?

Yes, if the ink is soy-based or mineral-based, which is standard for newspaper and most office printing. Avoid brightly coloured or metallic inks, which may contain heavy metals. When in doubt, keep the paper out of compost.

Is cardboard with printing on it safe to compost?

Yes, as long as the cardboard itself is uncoated. The printing ink on cardboard is usually soy-based and breaks down. Remove any plastic tape, labels, or plastic windows before adding the cardboard to your pile.

What about paper from the kitchen, like paper plates or paper towels?

Unbleached paper plates and paper towels compost. Most commercial paper towels are bleached, but the bleach breaks down in the compost environment. Avoid paper plates with plastic or wax coating on the inside.

How do I know if paper has a plastic coating?

Feel the inside of the paper or container. If it is slick or shiny and does not feel like paper, it has a coating. Bend it: uncoated paper creases easily, while coated paper may crack or feel stiff. When in doubt, throw it in recycling or trash.

Does shredded paper compost faster than whole sheets?

Yes. Shredding increases surface area, so microbes can break down the paper faster. Shredded newspaper may compost in 6 to 8 weeks, while whole sheets may take 6 months or longer.