Compost Heat & Decay Rate Calculator

Hot composting (regular turning, proper C:N): 3-6 weeks. Cold composting (minimal turning): 6-12 months. Kitchen scraps alone: 2-4 weeks in hot system. Yard waste (leaves): 4-6 months. Mixed materials: 3-4 months typical. Hot composting requires: C:N 25-30:1, moisture 40-60%, turning every 1-3 days, pile 3+ cubic feet minimum.

Heat comes from microbial activity. Key factors: Carbon-to-nitrogen ratio (ideal 25-30:1), moisture (should feel like a wrung-out sponge), oxygen (turning provides), particle size (smaller = faster), and pile size (minimum 3ft³ for heat retention). Cold/wet/small piles won't heat. Add greens (nitrogen) and turn to generate heat. Large piles (5-10ft³) retain heat best.

Ready compost is dark, crumbly, and earthy-smelling. Temperature returns to ambient. C:N ratio has processed. You can't identify original materials. Test: Put a handful in a bag - no bad smell after 24 hours. It should look like rich soil. Screen through ½" mesh if needed. Some curing (2-4 weeks) after active decomposition improves quality. Let rest before garden use.

Cold compost causes: Too small (<3ft³), wrong C:N ratio (add more greens if smelly, more browns if not heating), too dry (add water), too wet/soggy (add browns/turn), or too much nitrogen (balance with browns). Fix: Turn, add nitrogen (grass clippings, food scraps), ensure moisture, and mound pile to 3+ feet. Can take 2-4 weeks to heat after fixes. Outdoor piles take longer in cool weather.