Compost Calculator

Top-dressing rates are 1/4 to 1/2 inch deep. For 1,000 sq ft at 1/4 in: 1000 x (0.25/12) = 20.8 cu ft, about 0.77 cu yd. For amending garden beds, aim for 2-3 inches incorporated into the top 6 in of soil.

No. Material C:N ratios and volumes are not enough to calculate the combined ratio. You also need the carbon and nitrogen concentration or measured mass of each ingredient. This calculator estimates the amount of finished compost needed for an area.

Browns are carbon-rich materials such as dry leaves, straw, cardboard, and wood chips. Greens are nitrogen-rich materials such as grass clippings, food scraps, coffee grounds, and fresh manure. A fixed volume recipe cannot guarantee a target C:N ratio because moisture, density, and nutrient concentration vary.

Hot, well-managed piles can finish in weeks, while cooler piles can take many months. The timing depends on temperature, moisture, particle size, turning, and the materials used. Properly managed hot compost can reduce weed seeds and pathogens, but a single temperature reading does not make every input safe. Follow local extension guidance for manure, diseased plants, or compost used on food crops.

Yes, once it is finished (dark, crumbly, earthy-smelling, no recognizable scraps). Unfinished compost can tie up nitrogen as it continues to break down and may stunt plants. If in doubt, let it cure another month or use it as mulch instead of mixing in.