Household → bin size
Sizing bands follow the growperma / Penn State weekly-input tiers. Defaults: ~4 lbs of kitchen scraps per person per week.
Will this size go hot or stay cold?
Enter pile or bin dimensions. The hot threshold is 27 cu ft (3×3×3 ft) uninsulated, ~12 cu ft insulated (estimate).
Pile dimensions → volume
Seasonal leaf load sizing
Fall leaves arrive all at once — size a dedicated pile or extra bin so the main bin never backs up.
3-bin system planner
K-State's ideal layout: bin 1 collects fresh material, bin 2 is the active hot pile, bin 3 cures finished compost. Each bin holds one full batch.
Tumbler vs stationary bin
Speed claims are estimates for actively managed systems (~50% moisture, balanced greens/browns, turning schedule kept).
Placement / space validator
Checks bin + clearances against your available space: 1 ft airflow each side, 2 ft working access in front, 1 ft behind.
Good to know
- Planning estimates. Sizing bands come from published guides (Penn State Extension via growperma, eartheasy, yardique, homecompostguide, K-State Extension); densities and finish times are typical values, not guarantees.
- No meat or dairy in open bins and piles — they attract pests and go rancid. Some sealed tumblers are rated for them; follow the manual.
- Moisture ~50%: the wrung-out-sponge test. Water dry piles as you build; add dry browns if a pile gets soggy.
- Check local code and HOA rules before siting a bin — setbacks and enclosure rules vary.
Compost sizing FAQs
What size compost bin do I need?
Size the bin to your weekly input. Kitchen scraps only (4-8 lbs/week) fits a 40-60 gallon tumbler; a small backyard with scraps plus clippings (10-20 lbs/week) needs a 60-100 gallon enclosed bin; a family with a normal suburban yard (20-40 lbs/week) needs 100-130 gallons; a large yard with a seasonal leaf load (200+ lbs) needs 200+ gallons or two bins. A handy rule of thumb: pick a bin 2-4x your weekly volume, and when you are between two sizes, take the larger one.
How many gallons is a 3x3x3 ft compost pile?
A 3x3x3 ft pile is 27 cubic feet, which works out to about 202 gallons (764.6 liters) - exactly 1 cubic yard. That number matters: Penn State Extension puts the minimum pile for true hot composting (140-160 F core) at 3x3x3 ft, so one cubic yard is the hot-compost threshold in a single number.
How big does a compost pile need to be to get hot?
At least 3x3x3 ft - 27 cubic feet, about 200 gallons. Penn State Extension sets this as the minimum mass that holds a 140-160 F (60-71 C) core. Below that, an uninsulated bin loses heat through its surface faster than the microbes generate it, so it cold-composts instead. An insulated bin can run hot at a smaller size (roughly 12 cu ft is a fair planning estimate), because insulation - not bulk - is doing the heat-trapping work.
Can a small compost tumbler get hot?
Usually not from bulk alone. Most backyard tumblers (40-60 gallons) are well under the 27 cu ft hot threshold, so they cold-compost over 6-12 months - still fine, just slower. Sealed, insulated tumblers are the exception: they can reach about 150 F and finish a chamber in roughly 6-8 weeks. A well-managed regular tumbler (turned every 2-3 days in warm weather) typically finishes in 4-8 weeks without ever truly going hot.
What is a 3-bin compost system?
Three side-by-side bins with a job each, recommended by K-State Extension: bin 1 collects fresh material until you have a full batch; bin 2 holds the active, hot pile that you turn; bin 3 stores finished compost while it cures. Each bin should hold at least a 3x3x3 ft mound (27 cu ft) for hot composting, and 5x5x5 ft (125 cu ft) is the practical maximum - bigger than that is too hard to turn by hand.
How long does compost take?
A hot pile (27+ cu ft, turned, balanced) finishes in 6-12 weeks. A cold pile or small uninsulated bin takes 6-12 months. A managed tumbler lands in between at roughly 4-8 weeks in warm weather. Whatever the system, the pile shrinks to about 40-60% of its starting volume - a full cubic yard of raw material yields roughly 80-120 gallons of finished compost.
Should I get a tumbler or a stationary compost bin?
Pick a tumbler for kitchen-scrap-only volumes (up to ~8 lbs/week), fastest batch turnaround, and sealed pest protection. Pick a stationary bin for yard waste and leaves, larger capacity (bins hold 2-3x the volume per footprint), and continuous adding - you can toss scraps in anytime. Remember tumblers are batch systems: you stop adding fresh material to let a batch finish, which is why dual chambers exist.
What should I not put in my compost bin?
Skip meat, dairy, fats and oils in open bins and piles - they attract rats, raccoons and flies and go rancid before they break down. (Some sealed tumblers are rated for meat and cooked food - follow your model's manual.) Also avoid pet waste, diseased plants, glossy or chemically treated paper, and charcoal ash. Check your local code and HOA rules before siting a bin.
How wet should compost be?
Aim for about 50% moisture - the classic wrung-out-sponge test: squeeze a handful hard and only a few drops should come out. Below ~40% moisture microbes go dormant and the pile stalls; above ~60% water fills the air pockets, the pile goes anaerobic, and you get slime and odor. Water dry piles as you build them, and add dry browns if a pile gets soggy.
How much space do I need for a compost bin?
Plan the bin footprint plus working clearances: about 1 ft of airflow on each side, 2 ft of working access in front (for turning and harvesting), and 1 ft behind - so a 3x3 ft bin needs roughly a 5x6 ft area (30 sq ft). The average composter itself has a 4-6 sq ft footprint. Put it on level ground in partial shade, near a water source and your kitchen door - convenience decides whether you actually use it.