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Calcimator

Compost Ratio Calculator

Calculate your compost C:N ratio from green and brown materials. Get quality assessment and adjustment suggestions for optimal decomposition.

Inputs

cu ft
cu ft

Results

C:N Ratio

48.8:1

Quality AssessmentToo Much Carbon
Adjustment SuggestionAdd more green material. Try adding 30 cu ft of green material to reach a 30:1 ratio.
Total Material Volume20 cu ft
Green:Brown Volume Ratio0.33:1
Est. Finished Compost8 cu ft
Est. Decomposition Time24 weeks
How to Use This Calculator
  1. Measure or estimate the volume of your green (nitrogen-rich) materials in cubic feet — grass clippings, kitchen scraps, or fresh manure.
  2. Select the green material type that best matches your pile contents to apply the correct C:N ratio.
  3. Enter the volume of your brown (carbon-rich) materials — dry leaves, straw, cardboard, or wood chips.
  4. Choose the brown material type so the calculator can compute the weighted average C:N ratio.
  5. Review the C:N Ratio and Quality Assessment outputs — the ideal range is 25:1 to 35:1 for fast decomposition.
  6. Follow the Adjustment Suggestion to add more greens or browns, then check the estimated decomposition time and finished compost volume.
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