Compost C:N Ratio
Balance a compost pile's carbon to nitrogen ratio.
About Compost C:N Ratio
Each feedstock contributes carbon and nitrogen in proportion to its mass and its own C:N ratio; the pile's ratio is the carbon divided by the nitrogen. A roughly 30 to 1 ratio decomposes steadily; too much nitrogen smells and too much carbon stalls the pile.
Formula
Compost C:N Ratio
C:N = total carbon ÷ total nitrogen, with each mass split by its ratio
- C:N
- Carbon to nitrogen ratio of the pile
Worked example
With the default values below, Compost C:N Ratio returns Pile C:N Ratio of 43.2. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Browns (carbon) by weightminimum 0 lbs
- 20 lbs
- Browns C:Nminimum 1
- 60
- Greens (nitrogen) by weightminimum 0 lbs
- 5 lbs
- Greens C:Nminimum 1
- 20
Results
- Pile C:N Ratio
- 43.2
- Balance
- Too much carbon
- Pile Nitrogen
- 0.566 lbs
Step by step
- 1Values used
- 2Compost C:N Ratio
- 3Pile C:N Ratio= 43.2
- 4Balance= Too much carbon
- 5Pile Nitrogen= 0.566 lbs
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Compost C:N Ratio calculated?
C:N = total carbon ÷ total nitrogen, with each mass split by its ratio Each feedstock contributes carbon and nitrogen in proportion to its mass and its own C:N ratio; the pile's ratio is the carbon divided by the nitrogen.
Why does Compost C:N Ratio matter?
A roughly 30 to 1 ratio decomposes steadily; too much nitrogen smells and too much carbon stalls the pile.
What values do I need to enter?
This calculator takes 4 inputs: Browns (carbon) by weight, Browns C:N, Greens (nitrogen) by weight, Greens C:N. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.