How to use this calculator
Start by entering how many people live in your household and selecting your yard size. Then check the boxes for everything you plan to compost, pick your preferred composting method, and choose how quickly you want finished compost. The calculator instantly shows your recommended bin volume, dimensions, weekly input estimate, and annual output.
The results also include a green to brown ratio tailored to your selected materials, plus an estimate of how many standard garden beds you could amend each year with the compost you produce.
Frequently asked questions
What size compost bin do I need for a family of four?
A family of four composting kitchen scraps and some yard waste typically needs a bin of about 12 to 18 cubic feet. That works out to roughly a 2.5 foot cube or a tumbler in the 50 to 65 gallon range. Adding a lot of leaves and grass clippings may push you toward 25 cubic feet or a three bin system.
How long does it take to get finished compost?
With active turning and good moisture, you can have finished compost in four to eight weeks. A more relaxed approach with occasional turning takes two to four months. If you prefer a hands off passive pile, expect six to twelve months before everything is fully broken down.
What is the green to brown ratio for composting?
Aim for roughly two to three parts brown (carbon rich) material to one part green (nitrogen rich) material by volume. Browns include dried leaves, straw, cardboard, and paper. Greens include kitchen scraps, coffee grounds, and fresh grass clippings. Maintaining the right balance prevents odors and speeds up decomposition.
Why does my compost smell bad?
A smelly pile usually has too much green material or not enough airflow. Add more brown materials like dried leaves, shredded cardboard, or straw to absorb excess moisture. Turn the pile to introduce oxygen and make sure the bin has adequate ventilation. Also avoid adding meat, dairy, or oily foods, as these decompose slowly and attract pests.