Compost mix calculator (greens and browns)
Balance your compost pile: estimate the carbon-to-nitrogen ratio and moisture of your greens and browns, and what to add to fix a smelly or slow pile.
A compost pile works fastest at a carbon-to-nitrogen (C:N) ratio of about 25–35 and moisture like a wrung-out sponge. Too much nitrogen (greens) and it smells; too much carbon (browns) and it barely heats up. Enter what you’re adding, by the bucket or any equal measure.
Greens and browns
- Greens (nitrogen-rich, usually wet): grass clippings, kitchen scraps, coffee grounds, fresh garden plants, manure.
- Browns (carbon-rich, usually dry): dry leaves, straw, wood chips, sawdust, cardboard, newspaper.
Note that “parts” are by volume, and materials differ a lot in weight: a bucket of grass clippings weighs several times a bucket of dry leaves. That’s why roughly 2–3 buckets of browns to 1 of greens often balances.
Keep out: meat, dairy and oily food (attract pests), pet and human waste, diseased plants, weeds with seeds (unless your pile gets hot), and anything treated with herbicide. Some herbicides survive composting and damage vegetables.