What the numbers mean
Greens (fresh clippings, kitchen scraps) are nitrogen-rich, around 15:1 C:N. Browns (dry leaves, straw, cardboard) are carbon-rich, around 60:1. A pile near 30:1 C:N heats and breaks down well. By volume, that works out to roughly 2–3 parts browns to 1 part greens — this calculator gives that practical rule, not a false precise formula, because real materials vary.
Keep the pile moist like a wrung sponge, turn it regularly, and avoid meat, dairy and diseased plants in a home pile.