Compost Ratio Calculator
Balance greens and browns for fast compost.
Enter your values
ⓘ Live results
Results
- Current C:N ratio
- 45:1
- Verdict
- Too much brown — add greens
- Browns for target
- 10 kg
- Total pile mass
- 60 kg
Quick answer
Compost breaks down fastest at a carbon to nitrogen ratio near 30:1.
C:N = Σ(mass × C:N) ÷ Σmass
How to use the Compost Ratio Calculator
- 1Weigh your greens and browns.
- 2Use typical C:N values or look up your materials.
- 3Adjust until the ratio sits near 30:1.
Worked example
Using the values the calculator loads with:
Inputs
- Greens20 kg
- Greens C:N15
- Browns40 kg
- Browns C:N60
- Target C:N30
Results
- Current C:N ratio45:1
- VerdictToo much brown — add greens
- Browns for target10 kg
- Total pile mass60 kg
Frequently asked questions
What counts as greens?
Grass clippings, food scraps and manure.
Why does my pile smell?
Too many greens and not enough air — add browns and turn it.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.