Compost C:N Ratio Calculator
Estimate your compost pile's carbon-to-nitrogen ratio from greens and browns added.
Every calculation runs locally in your browser. Uses typical C:N ratios for each broad category (greens ≈15:1, browns ≈50:1) — actual ratios vary by specific material.
Estimated C:N ratio
26.7:1
Ideal range
For informational and educational purposes only — not professional advice, and not a substitute for consulting a qualified professional about your specific situation. TrueMeasureKit is not liable for decisions made based on these results. See our Terms of Service.
Why the ratio matters more than the total amount
Microbes breaking down compost need both carbon (energy) and nitrogen (protein for growth) in roughly a 25–30:1 ratio by weight to work efficiently. Too much nitrogen (too many greens) tends to produce a wet, smelly pile as excess nitrogen escapes as ammonia; too much carbon (too many browns) breaks down very slowly since the microbes don't have enough nitrogen to multiply. Balancing the mix, not just piling on more material, is what actually speeds up decomposition.
Frequently asked questions
What's the ideal carbon-to-nitrogen (C:N) ratio for compost?
A commonly cited target is around 25-30:1 (carbon to nitrogen) for efficient decomposition — too much carbon (browns) slows the process down, while too much nitrogen (greens) can cause odor and a slimy pile.
What counts as 'greens' versus 'browns'?
Greens are nitrogen-rich materials — fresh grass clippings, vegetable scraps, coffee grounds. Browns are carbon-rich materials — dry leaves, straw, cardboard, wood chips. Balancing both is what this calculator estimates from what you add.