Worm Bin Size & Feed Calculator
Size a vermicomposting bin, and know how many worms to start with, from your household's weekly food scraps.
How this calculator works
The standard vermicomposting rule is 1 cubic foot of bin space and 1 pound of red wiggler worms (roughly 1,000 worms) for every pound of food scraps produced per week. Bedding (shredded newspaper, cardboard, or coir) is estimated at roughly 2–2.5 lbs per cubic foot of bin volume to start, topped up every 1–3 months as worms consume it.
Where these numbers come from
- 1 cubic foot / 1 lb worms / 1 lb food-per-week rule: Oregon State University Extension (EM-9034, "Composting with Worms")
- Bedding quantity by bin size: Butler County (PA) Extension vermicomposting guide, cross-checked against University of Idaho Extension guidance
Keep the bin between 55–77°F and the bedding as moist as a wrung-out sponge — temperature and moisture matter more to worm health than getting the exact ratio perfect.
Frequently asked questions
How do I know how many worms to start with?
Worm population is typically sized against how many food scraps you generate weekly, since that's what determines how much the worms actually need to process — this calculator works backward from your own household's scrap volume rather than a flat starting number.
What happens if I add more scraps than the worms can process?
Overfeeding a worm bin relative to its worm population can lead to rotting food, odor, and pest problems before the worms catch up — sizing the bin and worm count to your actual scrap volume avoids that lag.
Does bin size matter as much as worm count?
Yes — worms need enough surface area and bedding volume to actually live and process waste comfortably, so an undersized bin can bottleneck things even with a large enough worm population.
Explore the whole Calcs family here.
Not happy with our calculations or how it works? Let us know.
Have a suggestion for a calculator you don't see here? Let us know.
All HomesteadCalcs tools
Animal Care
Beehive Box & Frame Count Calculator Beekeeping Sugar Syrup Calculator Backyard Chicken Feed Ration Calculator Dairy Goat Feed-to-Milk-Production Calculator Goat/Sheep Dewormer Dosing Calculator Backyard Quail Housing & Feed Calculator Rabbit Gestation & Litter Due-Date Calculator Acres per Animal Calculator Chicken Coop & Run Size Calculator Honey Yield Calculator Egg Hatch Date CalculatorGardening & Food
Canning & Preserving Altitude Calculator Cider Press Yield Calculator Maple Syrup Sap-to-Syrup Yield Estimator Maple Tree Tap Count Calculator Orchard Tree Spacing & Pollination Calculator Root Cellar Sizing & Storage Planner Seed Saving Isolation Distance Calculator Worm Bin Size & Feed Calculator Garden Yield & Space Calculator Planting Date Calculator Raised Bed Soil Calculator Compost Carbon-to-Nitrogen Ratio Calculator Canning Yield Calculator: Produce per JarOff-Grid & Rural
Firewood Cord & BTU Comparator Fur/Pelt Trapping Value Calculator Rain Barrel / Cistern Sizing Calculator Sawmill Log-to-Board-Feet Calculator Septic Tank / Leach Field Sizing Calculator Tractor PTO Horsepower & Implement Sizing Calculator Water Trough De-Icer Sizing Calculator Well Pump Sizing Calculator Solar & Battery Bank Calculator Generator Size CalculatorNo calculators match your search.