Compost Calculator - Right Bin Size for Your Household and Garden

Compost bin sizing - from studio flat to large garden

A family of four with a 400 m2 garden generates roughly 800 kg of compostable waste per year. That calls for a 400-liter bin and yields about 250 liters of finished compost - enough to top-dress 25 m2 of vegetable beds at 1 cm depth. The calculator matches bin size to your household and garden, then breaks down the numbers: kitchen waste, garden waste, yield and the brown-to-green ratio that keeps the pile from turning into a smelly mess.

Composter type atlas

Open wooden bin

Capacity: 400-800 L

Price: $30-80

Maturation: 6-12 months

Cheapest option. Easy to build from pallets. Large capacity. Exposed to rain and rodents.

Plastic enclosed bin

Capacity: 200-600 L

Price: $60-150

Maturation: 4-8 months

Retains heat and moisture. Keeps rodents out. Harder to turn manually. Most popular choice.

Tumbler / drum composter

Capacity: 100-300 L

Price: $120-350

Maturation: 6-8 weeks

Fastest decomposition. Spin to mix - no fork needed. Sealed against pests. Small batches only.

Worm bin (vermicomposter)

Capacity: 30-100 L

Price: $40-120

Maturation: 2-3 months

Works indoors or on a balcony. Produces premium vermicast. Kitchen scraps only - no garden waste.

How to use the compost calculator - step by step

Household size - each person produces about 120 kg of compostable kitchen waste per year (peels, coffee grounds, eggshells, tea bags).
Garden area (m2) - bigger gardens mean more green waste from mowing, raking and pruning. A 300 m2 garden generates roughly 240 kg of trimmings per year.
Composter type - pick a size manually or let the calculator auto-select based on your inputs. Small for 1-2 people, medium for 3-4, large for 5+.
Price (optional) - enter the price of the bin you are considering for a cost comparison.
Read the results - recommended capacity, annual waste breakdown, compost yield and the 75/25 brown-to-green ratio.

Bin size reference by household

Bin size	Best for	Waste/year	Yield/year	Price range
Small (300 L)	1-2 people, garden under 200 m2	~400 kg	~188 L	$50-100
Medium (400 L)	3-4 people, garden 200-500 m2	~800 kg	~250 L	$80-150
Large (600 L)	5+ people, garden over 500 m2	~1200+ kg	~375 L	$120-250

Composter type comparison - speed, price and effort

Type	Capacity	Price	Time to compost	Pros
Open wooden	400-800 L	$30-80	6-12 months	Cheap, large, easy to build from pallets
Plastic enclosed	200-600 L	$60-150	4-8 months	Retains heat, rodent-proof, tidy
Tumbler / drum	100-300 L	$120-350	6-8 weeks	Fastest, easy mixing, pest-proof
Worm bin	30-100 L	$40-120	2-3 months	Indoor/balcony, premium vermicast

What goes in - and what stays out

YES - compost these

Vegetable and fruit peels

Coffee grounds and tea bags

Eggshells (crushed)

Grass clippings (dried 24 hours)

Leaves, small branches (chopped)

Shredded cardboard and newspaper

Sawdust (untreated wood only)

Wood ash (small amounts)

NO - keep these out

Meat, fish and bones

Dairy products and fats

Pet waste (dog, cat litter)

Diseased or pesticide-treated plants

Weed seeds (they survive)

Treated or painted wood

Plastic, glass, metal

Disposable nappies

Practical examples

Couple (2 people), 150 m2 garden: 240 kg kitchen + 120 kg garden = 360 kg/year. Recommended: Small 300 L (~$70). Yields about 188 liters of compost per year.

Family of 4, 400 m2 garden: 480 kg kitchen + 320 kg garden = 800 kg/year. Recommended: Medium 400 L (~$100). Yields about 250 liters. Mature compost in 6-12 months.

Large family (6 people), 800 m2: 720 kg + 640 kg = 1,360 kg/year. Recommended: Large 600 L or two medium bins (~$160-200). Yields about 375 liters.

Apartment, no garden (1 person): 120 kg kitchen waste only. A worm bin (50-80 L) handles this easily indoors. Yields premium vermicast for houseplants. Cost: $40-80.

Impatient gardener (3 people, 300 m2): 360 + 240 = 600 kg/year. A tumbler composter (200-300 L) turns waste into compost in 6-8 weeks instead of 6-12 months. Costs more ($150-250) but delivers faster results.

FAQ

What size compost bin for a family of 4?

A 400-liter bin ($80-150) handles about 800 kg of waste per year. That covers kitchen scraps for 4 people plus clippings from a garden up to 500 m2. If your garden is larger, go for 600 L or run two bins side by side.

How long until compost is ready?

Open bin: 6-12 months. Enclosed plastic: 4-8 months. Tumbler: 6-8 weeks. Worm bin: 2-3 months. Ready compost is dark brown, crumbly and smells like forest floor - not sour or ammonia-like.

Why does my compost smell bad?

Too much green material (wet kitchen scraps, fresh grass) and not enough air. Fix: add dry leaves or shredded cardboard (brown material) and turn the pile with a fork. The target ratio is 3 parts brown to 1 part green by volume.

Do I need to turn the compost?

Yes - every 2-3 months with a garden fork. Turning adds oxygen, speeds decomposition and prevents anaerobic pockets (the source of bad smells). Tumbler composters solve this - just spin the drum once a week.

Can I compost grass clippings?

Yes, but dry them first. Fresh grass clippings mat together into a slimy, airless layer that rots instead of composting. Spread them on the lawn for 24 hours, then add in thin layers (max 10 cm) mixed with brown material.

Open bin vs tumbler - which is better?

Open bins are cheap, hold more and handle garden waste well - but they are slow (6-12 months) and attract rodents. Tumblers are faster (6-8 weeks), pest-proof and easy to mix - but they cost 3-5x more and handle smaller batches. For large gardens with lots of yard waste: open bin. For small gardens or impatient composters: tumbler.

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