Compost C:N Ratio Calculator

Blend a pile of greens and browns and find the overall carbon-to-nitrogen ratio, the key to hot, odor-free composting. Add each ingredient with its weight and the tool sums the carbon and nitrogen by mass (using each material's C:N ratio) to give the pile's blended ratio, classifies it as too green, balanced or too brown, and suggests how much of an adjuster to add to reach the ideal ~30:1. Microbes thrive around 30:1 — too much nitrogen (green) makes a smelly, slimy pile; too much carbon (brown) stalls decomposition. Pure arithmetic — real composting also depends on moisture, aeration, particle size and temperature, so the ratio is a starting guide. Everything runs locally in your browser.