Compost Bin Size Calculator
Calculate ideal compost bin volume from weekly yard and kitchen waste output.
Returns cubic feet and liters needed for active hot composting or cold composting.
Compost bin sizing is based on the volume of organic waste your household or garden produces and the space needed for the composting process to generate enough heat for effective decomposition. A bin that is too small will not heat up; a bin that is too large is difficult to manage.
Minimum effective volume:
The standard recommendation is a minimum of 1 cubic yard (27 cubic feet) for a hot-composting pile. This is the smallest volume that reliably achieves the 130–160°F (55–70°C) core temperatures needed to kill weed seeds and pathogens.
Volume formula:
Bin Volume (ft³) = Length × Width × Height
Bin Volume (m³) = Length(m) × Width(m) × Height(m)
Worked example: A household of 4 people wants to compost kitchen scraps and garden waste:
- Weekly kitchen waste: ~10 lbs
- Weekly garden clippings: ~15 lbs
- Estimated weekly volume: ~2 cubic feet of loosely packed material
- 12-week batch cycle
- Volume needed: 2 ft³/week × 12 weeks = 24 ft³ — so build a 27 ft³ (1 yd³) bin minimum
Bin dimensions for common sizes:
| Volume | Dimensions (L×W×H) | Good For |
|---|---|---|
| 27 ft³ (1 yd³) | 3×3×3 ft | 1–2 person household |
| 54 ft³ | 3×3×6 ft or two 3×3×3 bins | 3–5 people + garden |
| 108 ft³ | Three 3×3×4 ft bins | Market garden / small farm |
The three-bin system: For continuous composting, use three bins: one actively filling, one decomposing, one finished and curing. This gives a constant supply of ready compost.
Carbon-to-nitrogen ratio: Effective compost needs a C:N ratio of 25:1 to 30:1.
- Browns (carbon): dry leaves, cardboard, straw — C:N ~50–100:1
- Greens (nitrogen): food scraps, grass clippings, coffee grounds — C:N ~15–20:1
- Mix roughly 3 parts brown to 1 part green by volume for the ideal balance