Browns for Compost: The Complete List With C:N Values
Browns are your pile's carbon supply — dry, woody, papery material that keeps the nitrogen in greens from rotting into a smelly slurry. Because browns span from gentle (dry leaves, ~55:1) to extreme (sawdust, up to 500:1), knowing each material's number stops you from smothering a bin with a seemingly small scoop of sawdust. Values below merge Colorado State University Extension's GardenNotes #246 table with Cornell Waste Management Institute data.
Key takeaways
- Dry leaves at 30–80:1 are the everyday brown; shredded paper at 150–200:1 is the apartment fallback.
- Sawdust and wood chips (100–500:1) are concentrated carbon — thin layers only.
- Cardboard and newspaper values span 107–560:1 across Cornell's own datasets; treat any single number as a rough flag.
- Shred everything: surface area is speed.
- Keep a dry leaf stockpile in autumn — it's next summer's browns bank (see browns-shortage fixes).
The browns, ranked gentle to extreme
| Brown | Typical C:N | Range | Best use & cautions |
|---|---|---|---|
| Autumn leaves (dry) | 55:1 | 30–80:1 | Universal brown; shred with a mower to stop matting; stockpile dry |
| Peat moss | 38:1 | 38:1 | Mild brown, holds moisture; mined product, use sparingly |
| Corn stalks | 60:1 | 60:1 | Chop; slow but abundant after fall gardens |
| Straw | 70:1 | 40–100:1 | Hollow stems add air; avoid seedy hay |
| Bark / woody prunings | 115:1 | 100–130:1 | Long-cycle piles or reuse as mulch |
| Paper (shredded) | 175:1 | 150–200:1 | Office paper, receipts, non-glossy mail; wet it to stop it blowing |
| Cardboard (shredded) | ~334:1 | 107–560:1 | Remove tape/labels; superb browns bank when dry-stored |
| Newspaper (shredded) | ~338:1 | 115–560:1 | UMN lists shredded black-and-white news as acceptable home input |
| Sawdust | 300:1 | 100–500:1 | Powerful — sprinkle in thin layers; raw sawdust can seal a pile airless |
| Wood chips | 300:1 | 100–500:1 | Great bulk browns; screen out before using the compost |
How much of each to use
Think in terms of what each brown offsets. One kilogram of coffee grounds (20:1) needs roughly its own weight in leaves (55:1) to land mid-band — check any pairing in the C/N calculator. Two density cautions from the extension literature: UMN Extension flags that sawdust demands extra nitrogen (it's nearly pure carbon), and OSU's lasagna-composting guide reminds builders that cardboard — ideal at roughly a 30:1 mix — is itself a very high-carbon sheet that must be paired with greens, not laid alone.
Storing browns so they're ready when greens appear
- Leaves: whole dry leaves keep for a year in paper yard bags or a lidded bin; keep them dry so they stay carbon-rich and mold-free.
- Cardboard & paper: tear boxes flat when they arrive; a single stack under a bed is a family's winter browns supply.
- Straw & stalks: a covered heap or old bin keeps rain from leaching and matting them.
The full seasonal playbook — including why October is your bank-deposit month — is in short on browns? autumn leaf storage, cardboard and other fixes.
Browns that need a second thought
- Glossy or heavily printed paper: skip coated inserts; plain black-and-white newsprint is the accepted material.
- Treated wood products: never — preservatives don't belong in compost. UMN also warns against wood ash in quantity (alkalinity drives ammonia loss) and against creosote- or penta-treated lumber anywhere near a pile.
- Diseased prunings: home piles may not run hot enough to decontaminate them; municipal hot composting is the safer outlet.
Don't drown in browns either
A pile that is all browns doesn't smell — it just sits there for a year. If you're brown-rich, CSU's fallback works in reverse: a modest nitrogen source restarts the biology. Diagnose a stalled pile with a compost thermometer before adding anything.