Composting Calculator

Determine the perfect compost bin size, estimate finished compost production, and learn optimal carbon:nitrogen ratios for your composting needs. Calculate how much waste you'll divert from landfills.

Bin Size (gallons) = Weekly Waste (lbs) × 1.5 Finished Compost Volume = Original Waste × 0.45 (45% reduction) Annual Finished Compost (lbs) = Weekly Waste × 52 × 0.45 Landfill Diversion (cubic yards) = Annual Waste / 400 Carbon:Nitrogen Ratios: - Kitchen Scraps: 15:1 to 20:1 (nitrogen-rich, needs carbon) - Yard Waste: 30:1 to 40:1 (carbon-rich, needs nitrogen) - Mixed: 25:1 to 30:1 (ideal balance)
Example: 10 lbs/week of mixed kitchen and yard waste Bin Size = 10 × 1.5 = 15 gallons minimum Annual Waste = 10 × 52 = 520 lbs Finished Compost = 520 × 0.45 = 234 lbs per year C:N Ratio Target = 25:1 to 30:1 Composting Time = 3 months Landfill Diversion = 520 / 400 = 1.3 cubic yards This means you'll produce about 20 lbs of finished compost monthly!

What size compost bin do I need for my household?

For a household generating 10 lbs of compostable waste weekly, you need a minimum 15-gallon bin. A family of 4 typically produces 15-20 lbs of compostable waste weekly and needs a 30-40 gallon bin. Choose bins with at least 1.5× your weekly waste volume to allow for proper aeration and turning. Tumbler bins work well for 10-30 gallons, while larger households benefit from 50-80 gallon stationary bins.

How long does it take to make finished compost?

Composting time varies by material type and conditions. Kitchen scraps in a well-managed hot compost system can decompose in 2-3 months. Yard waste (leaves, branches) takes 4-6 months. A balanced mix of kitchen and yard waste typically composts in 3-4 months. Hot composting (maintaining 130-160°F) is fastest, while cold composting takes 6-12 months. Turning weekly, maintaining proper moisture, and balanced carbon:nitrogen ratios accelerate decomposition.

What is the ideal carbon to nitrogen ratio for composting?

The ideal carbon to nitrogen (C:N) ratio for composting is 25:1 to 30:1. Kitchen scraps (nitrogen-rich "greens") have ratios of 15:1 to 20:1, while yard waste (carbon-rich "browns") ranges from 30:1 to 80:1. Mix 2-3 parts brown materials (dried leaves, cardboard, straw) with 1 part green materials (food scraps, grass clippings, coffee grounds). Too much nitrogen creates odors; too much carbon slows decomposition. A balanced mix heats up quickly and decomposes efficiently.

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