Batch Ingredients

Add Ingredient to Pile

Pile Chemistry & Aerobic Simulation

Aerobic Zone
C:N Ratio 30:1 Target: 25:1 - 35:1
Moisture 54% Target: 45% - 60%
Total Mass 16.5 lbs 6.8 lbs Dry Matter
Peak Temp Est. 138°F Thermophilic active
Bin Cross-Section Volume
Airflow: 88% OK
Optimal Aerobic Decomposition: Good balance of moisture and porosity. Microorganisms will flourish without foul ammonia or sulfur off-gassing.

Est. Active Thermophilic Stage

14 – 21 Days

Turn pile every 4–5 days to sustain O2

Finished Cured Humus

8 – 12 Weeks

Yields ~7.5 lbs finished compost

Landfill Methane Emissions Avoided

In oxygen-starved municipal landfills, anaerobic bacteria digest moist food scraps (coffee grounds, carrots, peels) into raw CH4 (methane)—a greenhouse gas with 28× the 100-year warming potential of CO2. Aerobic home composting converts carbon safely into humus and biogenic CO2.

8.6 lbs
CO2e Diverted (EPA WARM)
Batch ready for aerobic composting.

The Science of Hot Composting

As highlighted in reports by The Associated Press, food scraps like coffee grounds, eggshells, and vegetable trimmings make up roughly 24% of municipal solid waste sent to landfills. When compressed into oxygen-deprived landfills, organic waste creates massive plumes of methane (CH4).

Aerobic composting relies on four foundational pillars:

  • Carbon (Browns): Provides energy and porosity for airflow (shredded cardboard, dry leaves, straw).
  • Nitrogen (Greens): Fuels rapid microbial cell division and protein synthesis (coffee grounds, vegetable peels, grass).
  • Moisture (45%–60%): Biological transport layer. Below 40%, microbial metabolism halts; above 65%, water displaces pore air pockets, triggering anaerobic rot.
  • Minerals (Eggshells): Calcium carbonate (CaCO3) neutralizes early acidic fermentation dips and fortifies soil structure.

Frequently Asked Composting Questions

Are coffee grounds considered a "Green" or a "Brown"?

Despite their brown appearance, used coffee grounds are biochemically a Green. They have a rich Carbon-to-Nitrogen ratio of roughly 20:1 and high moisture (~60%). They require balancing with high-carbon browns like dry leaves or cardboard.

Why add eggshells if they decompose slowly?

Eggshells consist of over 90% calcium carbonate. Even as slow-dissolving minerals, they act as an essential pH buffer against volatile organic acids produced during early vegetable breakdown, protecting beneficial thermophilic bacteria.

How does this calculator derive avoided methane emissions?

Using EPA Waste Reduction Model (WARM) factors: landfilling 1 lb of mixed wet food scraps produces approximately 0.52 to 0.65 lbs of CO2-equivalent in methane emissions over decay lifecycles. Diverting them into a well-turned aerobic pile averts this anaerobic methane generation entirely.

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