Compost C:N ratio calculator
PROWeighted C:N ratio of your compost mix. Target 25–30:1.
Inputs
Result
Mix C:N
48.8 : 1
target 25–30:1
Total weight
80 lb
% browns
75.00%
The formula
Mix C:N = Σ(weight × material C:N) ÷ total weight.
Worked example
60 lb browns (C:N 60) + 20 lb greens (C:N 15) = 48.75 : 1 (too many browns).
Frequently asked
›Why 25–30:1?
Microbes decompose fastest in that range; higher = slow, lower = smelly.