Last Updated on October 9, 2026
How Many Worms Do I Need for a Worm Bin?
Start with about 1 pound of red wigglers (about 1,000 worms) for every square foot of bin surface, and give the bin 1 square foot for every pound of food scraps your household makes in a week. So 2 pounds of scraps a week means a 2 by 1 foot bin and 2 pounds of worms. Both rules come from NC State Extension. Oregon State University Extension lands on the same ratio by volume: 1 pound of worms and 1 cubic foot of bin for each pound of scraps a week, in a bin no more than 1 foot deep.
You will also see a per-day ratio. Alabama Cooperative Extension says red wigglers eat 25 to 50 percent of their body weight a day, so a bin with 2 pounds of worms can handle half a pound to a pound of scraps a day. That is what a settled bin can reach. A new bin eats much less, so size your first bin by the weekly rule.
Worms, bin size and bedding by weekly scraps
Weigh what goes into your scrap container for one week, then find that row. Worms and bin surface follow the NC State rules above. Bedding is 4 to 6 inches deep, the depth Oregon State gives, and the gallons are arithmetic: 1 square foot at 4 inches is a third of a cubic foot, about 2.5 gallons.
| Scraps per week | Worms to start | Bin surface | Example inside size | Damp bedding, 4 to 6 in deep |
|---|---|---|---|---|
| 1 lb | 1 lb (about 1,000) | 1 sq ft | 12 x 12 in | 2.5 to 3.7 gal |
| 2 lb | 2 lb (about 2,000) | 2 sq ft | 24 x 12 in | 5 to 7.5 gal |
| 3 lb | 3 lb (about 3,000) | 3 sq ft | 24 x 18 in | 7.5 to 11 gal |
| 4 lb | 4 lb (about 4,000) | 4 sq ft | 24 x 24 in | 10 to 15 gal |
| 6 lb | 6 lb (about 6,000) | 6 sq ft | 36 x 24 in | 15 to 22 gal |
Oregon State gives two household examples. A family of two or three makes about 2 pounds of kitchen scraps a week, which fits a 1 by 1 by 2 foot bin with 2 to 2 1/2 pounds of worms. A family of four to six makes about 6 pounds a week and needs a 1 by 2 by 3 foot bin with up to 6 pounds of worms. Your own week of scraps is a better guide than any average, so weigh it.
NC State says to start with at least 1 pound per square foot to give the bin a chance to sustain itself. If you start with fewer, feed less until they multiply. Oregon State says red wigglers can double their population in about 60 days.
How much does a pound of red wigglers eat?
Sources disagree on how much an established pound of worms eats in a week, from about half a pound (Penn State Extension) up to three and a half pounds (Iowa State Extension). Start on the low end, the Alabama per-day rule above, and feed more only once the last batch is gone. NC State caps a working bin at up to 2 pounds a week per pound of worms, so treat the higher figures as a ceiling, not a target.
Alabama Extension warns that worms are easy to overfeed, which brings odor and excess moisture, and says to wait until the food looks eaten before adding more. If you make more scraps than the bin can take, NC State suggests more worms, a second bin, or a backyard compost pile for the extra. My composting for beginners guide covers the pile.
Set up the bin in six steps
- Weigh a week of scraps. University of Maryland Extension says to measure what your household makes first, then estimate the worms. Use the table above.
- Pick a dark, shallow bin. Oregon State says no more than 1 foot deep, because red wigglers live near the surface. Penn State says deep, narrow containers like 5-gallon buckets do not work well. NC State drills six 1/4-inch drainage holes in the bottom and air holes high on the sides, not in the lid, which would let in light and dry the bedding.
- Add damp bedding. NC State uses torn newspaper strips (not glossy paper), cardboard, paper bags, decaying leaves or coir, soaked 5 to 10 minutes and wrung out until only two or three drops come out when you squeeze it, plus a handful of garden soil. If you collect fall leaves for leaf mold, shredded leaves work too; Iowa State lists them as bedding.
- Add the worms on top. Use red wigglers (Eisenia fetida) bought by the pound from a worm grower. University of Maryland Extension says common garden worms and nightcrawlers quickly die in a worm bin.
- Wait, then feed lightly. NC State lets the worms settle for a couple of days, then adds scraps no more than 1 inch deep and covers them with 1 to 2 inches of bedding. Oregon State starts at 1/4 to 1/2 pound of scraps per pound of worms per week.
- Keep it cool, dark and topped up. Oregon State gives 55 to 77°F as the best range and says worms feed less below 50°F; NC State says never put the bin in direct sun. Oregon State keeps a 2-inch layer of fresh bedding over the worms and food, adding more as the old bedding is eaten.
If you weigh your bedding, University of Maryland Extension soaks 4 pounds of it in 1 1/2 gallons of water for its 2.2 square foot bin.
What not to feed worms
| Leave out | Why |
|---|---|
| Meat, poultry, fish, bones | They develop odors and draw other pests (Oregon State) |
| Dairy | Can cause anaerobic conditions and odors (Oregon State) |
| Citrus fruit and peels | Citric acid and limonene can be toxic to worms (UF/IFAS) |
| Onions and garlic | Sulfur compounds can harm worms; the papery skins are generally fine (UF/IFAS) |
| Grease, oil, fat, dressings | On the never list (NC State, UF/IFAS) |
| Salty foods like chips and pretzels | On the never list (Iowa State) |
| Pet waste and other feces | Waste from carnivorous pets can carry disease (UF/IFAS) |
| Tobacco | On the never list (NC State, Alabama Extension) |
NC State’s feed list is vegetables, fruits, crushed eggshells, tea bags, coffee grounds and shredded paper coffee filters, chopped small. UF/IFAS says to feed coffee grounds, plain grains and pasta, potatoes and eggshells in moderation. Go easy on cabbage-family scraps too: a Penn State Master Gardener found that too much cabbage, broccoli, cauliflower and kale made the bin smell. NC State sends citrus, onions and garlic to a backyard compost pile instead. NC State says many people keep scraps for a few days in a lidded container under the sink or in the freezer; my composting guide lists an indoor collection scrap bin for that.
Using the castings
NC State says castings start to show at the bottom of the bin after a few weeks and are ready to harvest in about four months: feed only one side for several weeks, let the worms move over, and scoop the finished side. Work the castings into a bed and keep them out of direct sun, or cover them with mulch. For how much to mix into a bed, the raised bed soil calculator does the volume.
Quick questions
How many worms are in a pound?
About 1,000 red wigglers, the figure NC State and Oregon State use. Oregon State notes that a pound you order may hold fewer, because some bedding ships in the mix.
Can I use earthworms from my garden in a worm bin?
No. University of Maryland Extension says common garden worms and nightcrawlers quickly die in a worm bin. Buy red wigglers (Eisenia fetida) from a worm grower.
How much food do worms eat a day?
In a settled bin, 25 to 50 percent of their body weight a day, according to Alabama Extension, so 1 pound of worms can handle about 1/4 to 1/2 pound of scraps a day. A new bin eats much less: Oregon State starts at 1/4 to 1/2 pound per pound of worms per week.
How deep should a worm bin be?
No more than about 12 inches, the Oregon State limit. NC State’s own example bin runs 8 to 20 inches deep. NC State sizes the bin by surface area, not depth.
Do I need to add more worms later?
Usually not. Oregon State says red wigglers can double their population in about 60 days, and Alabama Extension says they limit their own reproduction in a confined space. When you harvest, move extra worms to a second bin or give them away.
Plan the beds the castings go into
Castings go into beds, so plan the beds. Plan My Garden is free to start: enter your zip code, draw your beds, pick tomatoes, lettuce and everything else you want to grow, and it places each plant at square-foot spacing and builds a planting schedule from your frost dates.
Related: How to Compost for Beginners · Compost Ratio Calculator · How to Make Leaf Mold
