Know your ratio. Rot smarter.
CompostLab is a carbon-to-nitrogen calculator and a library of sourced guides for home composters. Blend your greens and browns by weight, land the mix in the 25–30:1 band, and fix the pile when it complains — with numbers from Cornell and university extension composting science, not folklore.
The tool: C/N ratio calculator
Enter materials and weights; get the blended C:N, an honest range, and exactly how much of any material brings the mix to 25–30:1.
Compost C/N ratio calculator
Weighted greens-and-browns blending with per-material ranges, moisture notes and an amendment solver for the 25–30:1 target.
Start hereThe carbon-nitrogen ratio, explained
Why 25–30:1 is the target, and why every published table gives slightly different numbers.
ReferenceGreens vs browns: the materials table
17 materials with typical C:N values, published ranges and sources.
All guides
Every number carries its source. Library last verified: against Cornell CWMI and CSU/OSU/UMN/NC State extension sources.
Composting methods compared: pile, bin, tumbler, bokashi, worms
Speed, space, effort and pest resistance — which vessel fits your waste stream.
ReferenceBrowns for compost: the complete list
Leaves to sawdust with C:N values, storage tactics and dosing cautions.
ReferenceGreens for compost: the complete list
Grass, scraps, coffee, manures — values plus how to keep wet greens aerobic.
TroubleshootingSmelly compost? Diagnose too-wet and too-green piles
Rotten-egg vs ammonia vs sour — diagnosis flows with the exact fixes.
TroubleshootingShort on browns? Leaf storage, cardboard and other fixes
Bank autumn leaves, build a packaging pipeline, know the emergency levers.
MethodsHot vs cold composting
130–160 °F versus the lazy bin: time, weed seeds, pathogens and effort.
VermicompostingWorm composting basics: moisture, bedding and feeding
Red wigglers at 75–85% moisture and 55–77 °F, from OSU's vermiculture guide.
BokashiBokashi basics: ferment first, then finish in soil
The indoor bucket that handles meat and dairy, and the 2-week soil finish.
Hot CompostingHow to use a compost thermometer
Temperature bands decoded: the active range, the too-hot line, when to turn.
HarvestUsing finished compost: how to know it's done
Earthy, dark, half the height — and how to spend it in beds, pots and lawns.
SeasonalWinter composting: what actually keeps working
Insulate with mass, cover against snow, and route scraps to indoor methods.
C/N RatioWhy estimates vary (and why that's fine)
Lab variability, dry-vs-wet mass, and the error bars behind every C:N table.
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