How do I know if packing peanuts are compostable?

So, you got a package in the mail, and it showed up stuffed with these weird-looking packing peanuts. They’re beige-colored cylinders, maybe a little curved, and stick to your fingers a little. Chances are, someone somewhere a while ago dared you to eat one, claiming that it was edible.

Insert mini-rant about edible versus non-toxic here…


The good news: these are starch-based peanuts, 100% biodegradable, 100% compostable, and they break down when exposed to water. They’re an excellent replacement for polystyrene-based packing peanuts since they do exactly the same job with much less post-consumer environmental footprint when disposed of properly.

The main drawback to starch-based packing peanuts is that they compress more under the same load as their polystyrene equivalent, as shown on Packability’s blog post on the topic. Rather than locking together and resisting compression through a sort of pseudo-crystalline structure the way polystyrene S-shaped peanuts do, cylindrical starch-based peanuts simply squish down. So, if you’re intending to reuse your packing peanuts rather than recycle or compost them (good for you!) we recommend saving your polystyrene peanuts for heavier items that could squish down starch-based peanuts during shipping.

It can be tricky to identify whether your packing peanuts are polystyrene- or starch-based without any prior experience, so here’s a short video showing you how. Starch-based peanuts will, as you can see, disintegrate into a sort of mush under the tap, and polystyrene peanuts won’t be affected at all. Starch-based peanuts also don’t carry a static charge like polystyrene does, so they won’t stick to your clothes unless they somehow get wet.

Another good test if you don’t have some water handy is to squish the peanut. If it compresses down easily and stays mostly squished, chances are it’s starch-based. When crushed, polystyrene peanuts will either hold their shape or fragment into little fluffy staticky chunks that cling to absolutely everything.

Once you’ve confirmed that you have starch-based packing peanuts, feel free to toss them in your compost! You can either fold them into the compost pile, or use a watering can to wet them down and help them break down first. It’s a perfect opportunity to add some moisture if your compost pile is looking a little dry.

If you don’t have a compost bin, a municipal compost service, or otherwise don’t have access to any form of composting, starch-based packing peanuts can also simply be emptied into a large bin, dissolved using warm or hot water, then once completely dissolved they can be poured down the drain. Provided the peanuts have properly dissolved, they’re both sewer and septic safe. Another option is to cut them into smaller pieces roughly the size of a pea, then mix into some potting soil to use in your garden.

Happy composting!

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