A compost pile works best near a 30:1 carbon-to-nitrogen ratio — too many browns and it sits there doing nothing, too many greens and it turns slimy and smelly. Add your materials below in any consistent unit (buckets, parts, or pounds) and this calculator estimates your pile’s ratio, then tells you exactly what to add to hit the sweet spot. Ratios are published averages, so treat the result as a guide. For the full how-to, see our composting guide.
Add your browns and greens in any consistent unit (buckets, parts, pounds — just be consistent). The calculator estimates your carbon-to-nitrogen ratio and tells you what to add to hit the sweet spot.
How the ratio is estimated
Each material has a published average C:N ratio. The pile’s ratio ≈ total carbon ÷ total nitrogen, weighting each material by its amount. Real-world ratios vary with moisture and particle size, so treat the result as a guide: aim for roughly 25–35:1. Too high (too many browns) = slow pile; too low (too many greens) = smelly, slimy pile.