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Compost Greens-and-Browns C:N Ratio Calculator

C:N_mix = (m_b + m_g) / (m_b/CN_b + m_g/CN_g) — target 25-30:1.

Compute the C:N ratio of a compost pile from the masses of brown carbon-rich material (CN ≈ 50:1 for dried leaves, straw, sawdust) and green nitrogen-rich material (CN ≈ 15:1 for grass clippings, kitchen scraps, manure), using the assumption of similar carbon mass-fraction in both. Target 25-30:1 for fastest decomposition.

Marcus Laurent By Marcus Laurent
Published Last reviewed 1 min read

Inputs

lb
lb

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

C:N_mix = (m_b + m_g) / (m_b / CN_b + m_g / CN_g).

In depth

Compute the C:N ratio of a compost pile from the masses of brown carbon-rich material (CN ≈ 50:1 for dried leaves, straw, sawdust) and green nitrogen-rich material (CN ≈ 15:1 for grass clippings, kitchen scraps, manure), using the assumption of similar carbon mass-fraction in both. Target 25-30:1 for fastest decomposition.