🌱 Compost Calculator
Calculate the optimal green-to-brown ratio for your compost pile to ensure proper decomposition and nutrient balance
Composting Analysis:
🌱 Compost Ratio Analysis
Your mix: 10 buckets grass clippings + 30 buckets dry leaves
Current C:N Ratio: 47.5:1
Status: Too Carbon-Rich (Brown Heavy)
Target Ratio: 30:1 (Standard Composting)
📊 Recommended Adjustments
To achieve 30:1 ratio:
- Add 8 more buckets of grass clippings (greens), OR
- Remove 12 buckets of dry leaves (browns)
💡 Tip: A balanced 30:1 ratio ensures optimal decomposition speed and temperature for pathogen destruction.
Preview example - actual calculations based on your inputs
How to Use This Compost Calculator
This compost calculator helps you achieve the perfect balance of green (nitrogen-rich) and brown (carbon-rich) materials for optimal composting. Whether you're managing a small backyard bin or a large-scale composting operation, proper ratios ensure efficient decomposition and high-quality compost.
- Select your green material type from the dropdown menu. Greens provide nitrogen and include fresh grass clippings, kitchen scraps, coffee grounds, and manure. Each material has a specific carbon-to-nitrogen (C:N) ratio.
- Enter the amount of green material you plan to use. You can use any unit of measurement (buckets, pounds, cubic feet) as long as you're consistent.
- Choose your brown material type from the options provided. Browns supply carbon and include dry leaves, straw, cardboard, and wood chips. These typically have higher C:N ratios.
- Input the amount of brown material available, using the same unit of measurement as your greens for accurate ratio calculation.
- Select your target C:N ratio based on your composting goals:
- 25:1 for fast, hot composting (reaches 130-160°F)
- 30:1 for standard balanced composting (optimal for most situations)
- 35:1 for slower decomposition with less odor
- Click "Calculate Compost Ratio" to analyze your current mix and receive specific recommendations for achieving your target ratio.
- Review the results showing your current C:N ratio, whether your mix is balanced, and exact adjustments needed to reach your target.
The calculator provides detailed recommendations including how many units to add or remove of each material type. Use the "Show detailed analysis" option to see calculation breakdowns and composting tips specific to your material combination. Results can be copied for reference or downloaded as a composting guide for your records.
How It Works
This compost calculator uses scientific C:N ratio formulas to determine the optimal balance for your compost pile:
- C:N Ratio Database: Each composting material has a known carbon-to-nitrogen ratio. The calculator maintains a comprehensive database of common materials with their established C:N values.
- Weighted Average Calculation: The tool calculates your pile's overall C:N ratio using the formula: Total C:N = (Carbon₁ × Amount₁ + Carbon₂ × Amount₂) ÷ (Nitrogen₁ × Amount₁ + Nitrogen₂ × Amount₂)
- Ratio Comparison: Your calculated ratio is compared against your target (typically 30:1) to determine if the mix is balanced, too nitrogen-rich (green heavy), or too carbon-rich (brown heavy).
- Adjustment Algorithms: The calculator determines exact amounts to add or subtract using inverse ratio calculations, providing multiple options to achieve your target ratio.
- Material Conversion: All calculations account for the specific C:N ratios of your chosen materials, ensuring accurate recommendations regardless of material combinations.
- Practical Recommendations: Results include practical adjustments in your chosen units, making it easy to measure and implement changes to your compost pile.
When You Might Need This
- • Home gardeners calculating the perfect green-to-brown ratio for backyard compost bins
- • Urban composters balancing kitchen scraps with shredded newspaper in apartment vermicomposting systems
- • Farmers optimizing large-scale windrow composting operations with crop residues and manure
- • Community gardens determining material ratios for shared composting systems
- • Schools teaching students about carbon-nitrogen balance in environmental science programs
- • Landscapers converting yard waste into nutrient-rich compost for clients
- • Municipal waste facilities managing organic waste diversion programs
- • Permaculture practitioners creating hot compost piles for rapid soil amendment production
- • Restaurant owners composting food waste with cardboard and paper products
- • Greenhouse operators producing custom compost blends for specific plant requirements
Frequently Asked Questions
What is the ideal carbon-to-nitrogen (C:N) ratio for composting?
The ideal C:N ratio for composting is typically 25:1 to 30:1. A 30:1 ratio provides optimal conditions for microorganisms to break down organic matter efficiently, maintaining proper temperature and minimizing odors. Ratios below 25:1 may produce ammonia smells and decompose too quickly, while ratios above 35:1 slow decomposition significantly. This calculator helps you achieve your target ratio by adjusting the amounts of green (nitrogen-rich) and brown (carbon-rich) materials in your compost pile.
How do I know if my compost has too much green or brown material?
Signs of imbalanced compost are easy to identify. Too much green material (low C:N ratio) results in a wet, slimy pile with ammonia or rotting odors, attracting flies and pests. Too much brown material (high C:N ratio) creates a dry pile that decomposes very slowly or not at all, remaining cool to the touch. This calculator analyzes your current mix and tells you exactly how much to add or remove of each material type to achieve optimal balance for efficient decomposition.
What materials count as 'greens' versus 'browns' in composting?
Green materials are nitrogen-rich and typically moist, including fresh grass clippings (25:1), kitchen scraps (15:1), coffee grounds (20:1), and fresh manure (15:1). Brown materials are carbon-rich and usually dry, such as dried leaves (60:1), straw (75:1), cardboard (350:1), sawdust (400:1), and newspaper (175:1). The numbers represent their C:N ratios. This tool includes common materials with their specific ratios, plus a custom option for materials not listed.
How accurate is this compost calculator for different composting methods?
This calculator provides accurate ratio calculations based on established C:N values for common composting materials. It works well for hot composting (25:1 ratio), standard composting (30:1), and slower cold composting (35:1). However, actual decomposition rates also depend on factors like moisture (40-60% ideal), aeration, particle size, and temperature. The calculator's recommendations serve as an excellent starting point, but you may need minor adjustments based on your specific conditions and observations of your compost pile's behavior.
Can I use this calculator for vermicomposting (worm composting)?
While this calculator focuses on traditional composting ratios, it can provide helpful guidance for vermicomposting with some adjustments. Worm bins typically require less brown material than traditional compost, operating well at 20:1 to 25:1 ratios since worms prefer more nitrogen-rich environments. Use the calculator's 25:1 setting as a starting point, but monitor moisture levels carefully as worm bins need consistent 80% moisture. Remember that worms cannot process all materials that work in traditional composting, so avoid citrus, onions, and meat products regardless of C:N calculations.