📦 Turns “two parts cardboard to one part coir” into exact shopping quantities
Worm Bin Bedding Ratio Calculator
Tell us your bin size and which bedding mix you’re using — we’ll work out exactly how much cardboard, coco coir, and water you actually need.
18 gal
5 gal60 gal
Total Bedding Needed45 L (12 gal)
💡 Whatever mix you use, moisten it until it feels like a wrung-out sponge before adding worms — check with our Moisture Calculator if you’re not sure.
Quantities are practical estimates based on common material densities (shredded cardboard, compressed coir bricks) — actual yield varies by how tightly you shred or compress materials, so treat these as a solid starting shopping list rather than an exact science.
How to Use This Calculator
Start with your bin’s real capacity, not a guess — check the label on your tote, or use our Bin Size Calculator first if you’re building from scratch.
Pick a fill level — two-thirds full is the standard recommendation for a new bin; go fuller only if you’re topping up an established one.
Choose the mix that matches what you have on hand — classic cardboard-and-coir is the easiest for beginners to source.
Hydrate before adding worms — dry bedding materials, especially coir bricks, need water added before they’re ready to use.
Understanding Your Results
Total Bedding Needed
Based on your bin size and fill level — this is volume, not weight, since bedding materials vary a lot in density.
Cardboard & Coir Amounts
Converted into things you’d actually buy — flattened moving boxes and compressed coir bricks — not just abstract liters.
Hydration Water
An estimate of how much water your coir bricks need to fully expand — under-hydrating is a common first-bin mistake.
Mix Ratio
Change the mix anytime to see how swapping cardboard-heavy for coir-heavy, or adding leaves, shifts your shopping list.
FAQs
Why does my bedding need to be hydrated before use?
Dry bedding — especially compressed coir bricks — can actually pull moisture away from your worms rather than holding it for them. Always fully hydrate coir before adding it to the bin, and dampen shredded cardboard until it feels like a wrung-out sponge, not just slightly damp.
Can I substitute peat moss for coco coir?
You can, at a similar ratio — but peat moss is naturally more acidic than coir, so keep an eye on your worms’ behavior and consider adding a bit of crushed eggshell to buffer the pH if you go this route. Coir is generally the easier, more forgiving option for beginners.
How often do I need to add more bedding?
Bedding breaks down gradually as worms consume it, so top up a thin layer every few weeks, or whenever the surface starts looking more like finished compost than bedding. There’s no need to redo the whole bin — just refresh what’s been consumed.
Is shredded paper a good substitute for cardboard?
Plain, non-glossy paper works fine mixed in with cardboard, though cardboard’s corrugated structure holds air pockets better, which helps with ventilation. Avoid glossy or heavily inked paper, since some coatings and inks aren’t worm-safe.
New to worm bins?
Read our full step-by-step setup guide before you buy.
