Compost Calculator
Balance a compost pile by volume. Tell the calculator how much finished compost you are aiming for, and it splits the build into greens and browns at the standard 1 to 3 guidance.
Your results
Worked example
You want about 300 L of finished compost, roughly one full bin:
- Total parts: 1 part greens + 3 parts browns = 4 parts
- One part: 300 ÷ 4 = 75 L
- Greens: 1 × 75 = 75 L
- Browns: 3 × 75 = 225 L
In practice you build this in layers over weeks, not in one load: a bucket of kitchen scraps and grass clippings (greens) for every three buckets of shredded leaves, straw, or torn cardboard (browns).
How this calculator works
Greens are the nitrogen side: grass clippings, kitchen scraps, coffee grounds, fresh manure. Browns are the carbon side: dry leaves, straw, shredded paper and cardboard, wood chips. The 1 to 3 split by volume is the widely taught guidance for a pile that heats up without going slimy or smelly. Too many greens is the common failure; when in doubt, add more browns.
Common questions
My pile smells. What is wrong?
Almost always too many greens or too much water. Fork in a generous layer of browns, which restores the ratio and soaks up moisture, and the smell usually settles within days.
Why is my finished compost less than the target?
Decomposition shrinks volume a lot: much of the pile leaves as water vapour and carbon dioxide. Build above the target, or keep adding in the same 1 to 3 ratio as the pile settles, to finish where you aimed.
Estimates only. Results are provided for planning purposes and use the 1 to 3 greens to browns volume guidance stated on this page. Actual composting rates vary with materials, moisture, and temperature. Mississippi Maple accepts no liability for decisions made using this calculator.