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Pick your household below, or drag the slider yourself — watch the bin grow to the exact size you need, live.
How much floor space your worms need inside the bin, based on roughly 1 sq ft per lb of weekly food waste. More surface area means faster processing and less odor risk.
A practical width × length so you can measure before you buy — or cut plywood if you're building your own.
Roughly 1 lb of red wigglers for every 3.5 lbs of weekly scraps. Starting undersized is safer than overloading a small population — they'll multiply to match your feeding rate over a few months.
An estimate of moistened coconut coir, shredded cardboard, or newspaper to fill the bin roughly a third full at setup.
It's built on widely-used vermicomposting rules of thumb (roughly 1 sq ft of surface area and 1 lb of worms per 3.5 lbs of weekly food waste), not a rigid formula. Climate, bin depth, and how finely you chop your scraps can all shift the ideal size slightly — treat this as a confident starting point, not a strict limit.
Beyond about 20-25 lbs a week, most people find it easier to run two separate bins rather than one oversized one — it's simpler to manage moisture and airflow, and if one bin ever has an issue, you're not risking your entire worm population at once.
Yes — starting a size or two smaller is usually safer than starting too big. An undersized bin just means feeding a bit less often; an oversized bin with too few worms can go anaerobic and start to smell before the worm population catches up.
Functionally, no — worms don't care about the shape as long as the surface area is right. It's purely about what fits your space. Rectangular bins tend to slide more easily under counters and into closet corners.
Not at all — use this as a minimum guideline and round up to the nearest common tote or bin size available to you. A little extra room never hurts; going meaningfully smaller is what causes problems.
If food is consistently taking longer than a week to disappear, or you're noticing odor even with light feeding, that's usually a sign your worm population (or bin size) needs to grow. Re-run this calculator with your current weekly scraps to see the updated recommendation.
