What size compost bin do I need?

For most households with a yard, a 40–80 gallon enclosed bin handles kitchen scraps and light yard waste. Add real yard waste and you want a full cubic yard (3×3×3 ft) or a bin plus a separate leaf pile. With no outdoor space at all, size stops mattering and the system changes: a worm bin or bokashi buckets instead.

How big does a compost pile have to be to get hot?

About one cubic yard — 3×3×3 ft, roughly 200 gallons. Below that a pile cannot insulate its own core, so it never holds the 130–160°F that fast composting needs. It will still compost, just slowly and cold, which is a perfectly good outcome if you are not in a hurry.

Can a compost bin be too big?

For a tumbler, yes in a practical sense — a drum you cannot turn when it is full is a drum you stop turning. Open bins are more forgiving, but a pile much wider than about 5 ft stops getting oxygen to its center, which is why large systems are built as several bays rather than one huge heap.

How much compost material does a household actually produce?

This tool plans on roughly 0.75 gallons of kitchen scraps per person per week — a volume conversion of the per-capita household food-waste figures EPA publishes (on the order of 0.6 lb per person per day). It is an average: a household that cooks from raw ingredients produces far more than one that eats out. Yard waste dwarfs it either way, which is why the yard question moves the answer most.

What if I have no outdoor space?

Vermicomposting is the standard answer — a worm bin is quiet, compact, and odorless when run correctly. Plan roughly one square foot of bin surface per pound of scraps per week. Bokashi is the other route: it ferments everything, meat and dairy included, in a sealed bucket, but the fermented material still needs somewhere to finish, such as a planter or a curbside cart.

bin size calculator

Four questions, one right-sized recommendation — from a countertop-adjacent worm bin to a three-bay backyard system.

This calculator needs JavaScript. Rules of thumb: hot composting needs at least 1 cubic yard (3×3×3 ft); an average household's food scraps suit a 40–80 gallon enclosed bin; no outdoor space means a worm bin or bokashi buckets.

how the recommendation is made

Two things decide a composting system, and only one of them is volume. The tool works out how much material you generate each week, then checks that against the constraints that override volume entirely — because if you have no outdoor space, it does not matter how much you produce; you are worm composting either way.

The volume estimate is deliberately simple. Each person in the household is counted at about 0.75 gallons of kitchen scraps per week — a volume conversion of the per-capita household food-waste figures EPA publishes, on the order of 0.6 lb per person per day. Yard waste is then added as a flat weekly volume: nothing for no yard, about 4 gallons for a small lawn, about 12 for a big lawn with trees. Those yard numbers are the ones that actually move the answer. A four-person household's food scraps are roughly 2.6 gallons a week; one autumn's leaves from a mature maple will bury that many times over, which is why "how much yard waste" changes the recommendation more than "how many people" ever does.

Then the overrides run, in order. No outdoor space always returns a worm bin, whatever the volume says. A balcony or patio returns a sealed tumbler if you picked rodent-proofing or speed, and a bokashi pair otherwise, because those are the only systems that genuinely work on a hard surface with neighbours nearby. Heavy yard waste plus a large yard goes straight to a three-bay system — that combination needs turning room more than it needs a container. Only if none of those apply does the weekly volume pick between a small tumbler, a classic enclosed bin, and a bin-plus-leaf-pile combination.

worked examples

Three runs through the same logic, so you can see where the thresholds sit:

Two people, no yard waste, a small yard, easiest to run. Weekly volume is 1.5 × 0.75 = about 1.1 gallons, and no override applies. Under the 2-gallon threshold, so the answer is a small enclosed bin or tumbler, 40–80 gallons — small households never generate the mass a big pile wants.
Four people, no yard waste, a small yard, easiest to run. Now 3.5 × 0.75 = about 2.6 gallons a week. That clears the first threshold but stays under 6, so it returns the classic enclosed backyard bin, 80 gallons to a cubic yard. Add "a little" yard waste to the same household and you are at 6.6 gallons — over the top threshold, and the answer changes to a bin plus an open leaf pile, because one container stops being enough.
Five or more people, a lot of yard waste, indoors only. The volume here is large — 5.5 × 0.75 + 12, over 16 gallons a week — and it is ignored completely. No outdoor space means a continuous-flow worm bin, with bokashi and curbside drop-off named as the realistic overflow. This is the case that shows the rule ordering: constraints beat arithmetic.

a cubic yard is the number worth remembering

If you take one figure away from this page, make it that one. A cubic yard — 3×3×3 ft, about 200 gallons — is the smallest pile that reliably insulates its own core well enough to reach and hold the 130–160°F range that fast, hot composting needs. Under that, you are cold composting: still perfectly good compost, just measured in seasons rather than weeks, and without the heat that kills weed seeds and most pathogens. Nothing is wrong with cold composting — most backyard piles are cold — but it is worth knowing which one you have chosen, because it decides what you can safely put in. Anything on this site marked "careful" for pathogen or seed reasons is usually assuming a hot pile.

how much does a yard of compost weigh?

About 1,000 pounds. University of Minnesota Extension describes a typical finished compost as roughly half water by weight and puts a fresh cubic yard of it at 1,000 lb, with 800 to 1,500 lb as the spread you actually meet; UNH Extension's compost-buying tip sheet tells buyers to expect the same 1,000 lb per cubic yard, plus or minus a few hundred. Water is what moves that number, not what went into the pile — the same yard weighs noticeably more after a wet week than it does at the end of a dry August.

Half a ton sitting in a 3×3×3 ft box is worth picturing before you build one. It is why balcony and roof-deck composting is a bucket-and-tumbler business rather than a bay system, why a tumbler you cannot turn when it is full is a tumbler you stop turning, and why bays go on soil rather than on a platform. It is also the conversion to reach for when compost is sold by the yard instead of made at home: a cubic yard is 27 cubic feet, which puts one of the 1-cubic-foot bags at the garden center near 37 lb against that same 1,000.

Whatever size you land on, the mix inside it matters more than the box. Once you have a system, the browns & greens calculator balances what goes in it, and the printable cheat sheet is the fridge-door version for everything else.

common questions

What size compost bin do I need?: For most households with a yard, a 40–80 gallon enclosed bin handles kitchen scraps and light yard waste. Add real yard waste and you want a full cubic yard (3×3×3 ft) or a bin plus a separate leaf pile. With no outdoor space at all, size stops mattering and the system changes: a worm bin or bokashi buckets instead.
How big does a compost pile have to be to get hot?: About one cubic yard — 3×3×3 ft, roughly 200 gallons. Below that a pile cannot insulate its own core, so it never holds the 130–160°F that fast composting needs. It will still compost, just slowly and cold, which is a perfectly good outcome if you are not in a hurry.
Can a compost bin be too big?: For a tumbler, yes in a practical sense — a drum you cannot turn when it is full is a drum you stop turning. Open bins are more forgiving, but a pile much wider than about 5 ft stops getting oxygen to its center, which is why large systems are built as several bays rather than one huge heap.
How much compost material does a household actually produce?: This tool plans on roughly 0.75 gallons of kitchen scraps per person per week — a volume conversion of the per-capita household food-waste figures EPA publishes (on the order of 0.6 lb per person per day). It is an average: a household that cooks from raw ingredients produces far more than one that eats out. Yard waste dwarfs it either way, which is why the yard question moves the answer most.
What if I have no outdoor space?: Vermicomposting is the standard answer — a worm bin is quiet, compact, and odorless when run correctly. Plan roughly one square foot of bin surface per pound of scraps per week. Bokashi is the other route: it ferments everything, meat and dairy included, in a sealed bucket, but the fermented material still needs somewhere to finish, such as a planter or a curbside cart.