This free compost bin size planner helps you size a compost bin from your household size and the garden waste you enter, and see how many bins a steady supply needs. A bin that is too small overflows and smells, while a bin that is too big never heats up well, so the right size matters from the first day. It runs fully in your browser, so nothing you type is sent to a server. You need no account and no sign-up to use it.
The right bin size keeps the pile hot enough to break down fast and small enough to turn with a fork. When the pile is the right size, microbes work well, smells stay low, and you get finished compost sooner instead of a cold heap that sits for a year.
To use the tool, fill in the boxes on screen and press the calculate button. You can change any number and calculate again as often as you like. The result updates at once, so you can test different plans side by side and see which one fits your garden best.
For example, take four people who make 1.75 kilograms of waste each per week, with a 300 litre bin. The tool shows 28 litres a week, 224 litres over eight weeks, and one bin needed. Raise the household to six people at 2 kilograms each and the same math asks for two 200 litre bins.
In summer a pile fills faster because grass cuttings and soft prunings arrive every week, so size the bin for your busiest month, not for a quiet winter average. A bin sized for summer still works in winter, but a bin sized for winter will overflow in June.
Tip: Weigh your waste for two normal weeks before you buy. A guess made in a busy garden week will oversize the bin for the rest of the year.
Tip: Plan for two bins if you have the space. One bin fills while the other matures, so you never have to stop composting.
Tip: Keep loose material in mind. Shredded leaves pack tighter than whole branches, so chop bulky waste before you judge the volume.
The most common mistake is buying the biggest bin in the shop and filling it only a third full. A small pile loses heat fast, so the composting slows down and the pile can smell. It is better to fill one right-sized bin well than to half-fill a giant one.
Common question: How much waste does one person make? It varies a lot, but 1 to 2 kilograms a week of kitchen and garden waste is a fair starting point for most households.
Common question: Does the tool count grass cuttings? Yes, if you include them in the weekly waste number. Cuttings are bulky, so weigh them on a mowing week too.
Common question: Is one bin ever enough? Yes, for a small household with little garden waste. The tool tells you when one bin covers eight weeks of waste.
Home gardeners, allotment holders, and families starting their first compost pile use this kind of sizing check. It also helps anyone replacing a cracked bin who wants proof of the right size before spending money.
Keep a note of your pile dates and results through the season. After a few months you will see which mixes heated fastest and which plans finished on time. That record is worth more than any guess, because it comes from your own garden and your own waste.
Before you build the pile, read your plan once as if you were doing it tomorrow. Do you have the browns, the space, and the dates clear? If anything looks unclear, fix that line before you start. A plan that needs no guesswork works far better than a bigger plan that confuses you.
This tool is free to use as often as you like. Bookmark it and come back whenever you start a new pile or plan a harvest. A clear plan helps you compost with less smell, fewer flies, and more finished compost for your beds.
Remember that every result here is an estimate for home composting, not professional advice. Your local climate, your waste mix, and your bin type all shape the real result, so use the tool as a starting point and adjust it to your own garden.