Skip to content
Scapiera

Compost Calculator

Add your compost ingredients to estimate the overall carbon-to-nitrogen ratio. Get instant feedback on whether to add more browns or greens for the ideal 25-30:1 C:N balance. Results are approximate and intended for planning purposes only — always consult a professional for final specifications.

Calculate Your Compost Mix

Add Ingredient

lbs

Your Compost Pile

No ingredients added yet. Add materials above to estimate your C:N ratio. Results are approximate and for planning purposes only.

Carbon : Nitrogen Ratio

—

Too much NIdeal (25-30)Too much C

Balance Assessment

—

—

Total Weight

—

Estimated Volume

—

Total Carbon

—

Total Nitrogen

—

How to Balance Your Compost

  1. 1

    Add your ingredients

    Select each material you plan to add to your compost pile and enter its weight. Mix both green (nitrogen-rich) and brown (carbon-rich) materials for the best results.

  2. 2

    Review your C:N ratio

    Check the calculated carbon-to-nitrogen ratio. The ideal range is 25:1 to 30:1. A ratio in this range will decompose efficiently without odor problems.

  3. 3

    Adjust the balance

    If the ratio is too low (too much nitrogen), add more browns like dry leaves, straw, or cardboard. If the ratio is too high (too much carbon), add more greens like grass clippings or food scraps.

  4. 4

    Monitor moisture and turning

    Your compost should feel like a wrung-out sponge — moist but not dripping. Turn the pile every 1-2 weeks to add oxygen and speed decomposition.

Pro Tips

  • Aim for a C:N ratio between 25:1 and 30:1 — this is the sweet spot where microorganisms break down material fastest.
  • Your compost pile should feel like a wrung-out sponge — about 50-60% moisture. Too wet creates odor; too dry slows decomposition.
  • Turn your compost pile every 1-2 weeks to introduce oxygen. More turning means faster composting.
  • Shred or chop large materials before adding them — smaller pieces decompose much faster than whole leaves or large cardboard sheets.
  • Avoid adding meat, dairy, oils, or pet waste to home compost piles — these attract pests and can introduce pathogens.
  • Layer greens and browns like a lasagna — alternating thin layers mixes the materials evenly and jumpstarts decomposition.

Frequently Asked Questions

What is the ideal C:N ratio for compost?
The ideal carbon-to-nitrogen ratio for compost is between 25:1 and 30:1. At this ratio, microorganisms have enough nitrogen for growth and enough carbon for energy. A pile at 25-30:1 will heat up quickly and produce finished compost in 2-3 months.
What happens if there is too much nitrogen in my compost?
When the C:N ratio drops below 20:1 (too much nitrogen), the pile becomes slimy and produces a strong ammonia smell as excess nitrogen escapes as gas. Fix this by adding carbon-rich browns like dry leaves, straw, or shredded cardboard until the smell subsides.
What happens if there is too much carbon in my compost?
When the C:N ratio exceeds 40:1 (too much carbon), decomposition slows dramatically because microorganisms lack sufficient nitrogen to reproduce. A high-carbon pile can take 6-12 months or longer. Add nitrogen-rich greens like grass clippings or food scraps to speed things up.
How long does compost take to be ready?
With a proper C:N ratio (25-30:1), adequate moisture, and regular turning, hot composting produces finished compost in 2-3 months. Cold composting (no turning) takes 6-12 months. Vermicomposting (with worms) takes 3-6 months.
Can I add citrus peels to my compost?
Yes, citrus peels are fine in moderate amounts. They are acidic and contain d-limonene, which can temporarily slow decomposition, but they break down well when mixed with other materials. Chop them into smaller pieces to speed up the process.
How big should my compost bin be?
A compost pile needs to be at least 3 feet x 3 feet x 3 feet (1 cubic yard / about 0.76 cubic meters) to generate enough heat for efficient decomposition. Smaller piles won't heat up well; piles larger than 5x5x5 feet may not get enough air in the center.

Results are approximate and intended for planning purposes only. Material densities, coverage rates, and quantities are estimates that may vary based on actual conditions, product specifications, and installation methods. Always consult a professional for final specifications.

Related Tools

Soil

Estimate soil volume for raised beds, garden plots, and containers.

Mulch

Calculate how much mulch you need for any garden bed.

Plant Spacing

Find the right spacing and total plant count for any bed.