Compost Ratio Calculator
Green/Brown Ratio
Calculate the right mix of greens and browns for composting
Compost Pile Size
Calculate if your compost pile is big enough for hot composting
Formula
Weighted C:N = (Green Volume × Green C:N + Brown Volume × Brown C:N) / (Green + Brown Volume) | Ideal: 25-35:1
Frequently Asked Questions
What is the ideal carbon to nitrogen ratio for compost?
The ideal C:N ratio is 25:1 to 35:1, with 30:1 being optimal. This is roughly achieved by mixing 3 parts brown materials (carbon) to 1 part green materials (nitrogen) by volume. The correct ratio ensures fast decomposition without odors.
What are examples of green and brown compost materials?
Greens (nitrogen): grass clippings, kitchen scraps, coffee grounds, fresh manure, green plant trimmings. Browns (carbon): dry leaves, straw, cardboard, newspaper, wood chips, sawdust. Avoid meat, dairy, and pet waste.
Why does my compost smell bad?
Bad odor usually means too much nitrogen (greens) or too much moisture. Add brown materials like dry leaves or shredded cardboard, and turn the pile to add oxygen. A well-balanced compost pile should smell earthy, not rotten.
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