Rediscover Rural · Free Tool
Compost Calculator
Get your carbon-to-nitrogen ratio right instantly — add your materials, see your balance live, and find out exactly what your pile needs.
Your compost balance — live
Add materials below
C:N ratio —
Add green and brown materials below to see personalised advice for your pile.
🌿 Green Materials
Nitrogen-rich — grass, food scraps, fresh plant matter
🍂 Brown Materials
Carbon-rich — dried leaves, straw, cardboard, wood chips
🗑️ Bin / Pile Size
We use this to estimate how much material you need and your turning schedule
Your Compost Results
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Total material added
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Bin fill level
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Estimated ready time
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Recommended turning
Material Reference Guide
Carbon-to-nitrogen ratios for common homestead compost ingredients
| Material | Type | C:N Ratio | Notes |
|---|---|---|---|
| Fresh grass clippings | GREEN | 15–20:1 | Best in thin layers to avoid matting |
| Vegetable scraps | GREEN | 12–20:1 | Chop small for faster breakdown |
| Coffee grounds | GREEN | 20:1 | Excellent activator, adds nitrogen |
| Chicken manure (fresh) | GREEN | 7–10:1 | Hot — excellent activator in small amounts |
| Goat / sheep manure | GREEN | 20–25:1 | Cooler than chicken, very easy to use |
| Fresh plant trimmings | GREEN | 15–25:1 | Avoid diseased or pesticide-treated plants |
| Fruit peels and cores | GREEN | 20–35:1 | Bury to discourage pests |
| Dry autumn leaves | BROWN | 40–80:1 | Shred if possible for faster composting |
| Straw | BROWN | 80–100:1 | Excellent carbon source, good structure |
| Cardboard (plain) | BROWN | 350–500:1 | Tear into small pieces, remove tape |
| Wood chips | BROWN | 400–500:1 | Use sparingly — very high carbon |
| Sawdust | BROWN | 200–500:1 | Very high carbon — use thin layers |
| Newspaper | BROWN | 175:1 | Shred for best results, black ink only |
| Pine needles | BROWN | 60–110:1 | Break down slowly, use in moderation |
Frequently Asked Questions
The most common composting questions from homesteaders
What is the ideal carbon-to-nitrogen ratio for compost? ›
The ideal C:N ratio for active composting is between 25:1 and 30:1. At this ratio your pile will heat up properly, break down efficiently, and produce finished compost in the shortest time. Too much nitrogen (below 20:1) produces a slimy, smelly pile. Too much carbon (above 50:1) slows decomposition dramatically — the pile breaks down eventually but takes months rather than weeks.
How do I know when my compost is ready? ›
Finished compost looks dark brown, crumbles easily, smells earthy like forest floor (not rotting food), and you cannot identify any of the original materials except possibly some woody pieces. Temperature: the pile no longer heats up when you turn it. Time: most homestead piles take 2 to 6 months with regular turning and correct moisture.
My pile smells bad — what went wrong? ›
A bad smell almost always means one of two things. A rotten-egg sulphur smell means the pile is too wet and anaerobic (not enough oxygen). Fix it by adding dry brown materials, turning to introduce air, and covering during heavy rain. An ammonia smell means too much nitrogen — add more brown carbon materials like dry leaves or straw and turn well.
How often should I turn my compost pile? ›
For hot active composting, turn every 3 to 7 days to maintain heat and oxygen. The pile should reach 130 to 160°F (55 to 70°C) in the centre. For passive cold composting, turning monthly is sufficient — it just takes longer to finish. The smell test is the best guide: a pile that smells earthy and warm is working well. One that smells bad needs turning.
Can I compost chicken manure directly? ›
Yes, but with caution. Fresh chicken manure is very high in nitrogen and ammonia and can burn plants if applied directly to soil. Add it to your compost pile as a green activator in modest quantities — it dramatically speeds up decomposition. Mix with plenty of brown carbon material like straw or dry leaves. After proper hot composting (maintaining 130°F+ for several days), chicken manure compost is safe to apply to your garden.
What should I never put in my compost pile? ›
Avoid: meat, fish, and bones (attract pests, create odours), dairy products, diseased plants, weeds that have gone to seed (unless your pile gets hot enough to kill seeds), pet waste from dogs and cats (pathogen risk), plants treated with persistent herbicides, and coal ash. Wood ash in small quantities is fine. Most other organic matter composts safely.