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About this tool
Estimate finished compost yield, the browns needed to balance the C:N ratio and the waste you divert from landfill each year.
Composting kitchen waste is a mass balance: water evaporates, roughly half the dry organic matter is respired away as CO2 by the microbes, and what remains is finished compost at around 40% moisture. This estimator runs that balance on your weekly waste, and first solves the carbon-to-nitrogen blend — kitchen scraps sit near 20:1 and a pile works best near 30:1, so it calculates exactly how much dry brown material to add by weight.
Open Kitchen Waste Compost Estimator on AltFTool — it loads instantly in your browser.
Enter the values you already know.
Fine-tune the options to match your scenario.
Read the result and use it in your planning or reporting.
Balances greens and browns on dry weight, the way the chemistry actually works.
Models water loss and carbon respiration separately instead of applying a flat percentage.
Reports the nitrogen in your compost and what that is worth as urea equivalent.
Around 25 to 35% of the wet weight you put in, once the browns are included. Most of the loss is water evaporating, with roughly half the dry organic matter respired away as carbon dioxide, so 60 kg of mixed feedstock a year yields something like 20 kg of finished compost.
About 25:1 to 30:1 at the start. Below that the pile goes anaerobic and smells of ammonia because there is surplus nitrogen; much above it the pile stays cold because the microbes run short of nitrogen to build cells with. Kitchen scraps are around 20:1, dry leaves 60:1 and cardboard 350:1.
It depends entirely on the brown. Balancing dry leaves at 60:1 against kitchen scraps at 20:1 needs about one part browns to one part greens by dry weight, but cardboard at 350:1 needs only about half a part. Because browns are dry and greens are three-quarters water, the volumes look very different from the weights.
Not in an open or passive home heap. They attract rodents and flies and rarely reach the temperature needed to break down safely. Vegetable and fruit peel, coffee grounds, eggshells, and garden material compost cleanly; meat, dairy and cooked oily food are better handled by a sealed bokashi system or municipal collection.
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