Composting is supposed to be simple: throw organic matter in a pile and wait. But often, gardeners end up with a slimy, smelly mess (too much Green) or a cold, dry pile that sits unchanged for years (too much Brown). The secret to “Black Gold” is balancing Carbon and Nitrogen.
The ideal compost pile hits a Carbon-to-Nitrogen (C:N) ratio of 30:1. Stop guessing with your pitchfork. Use our Compost C:N Ratio Calculator below to mix your ingredients perfectly every time.
🍂 Compost C:N Ratio Calc
How to Use This Tool
This tool helps you balance two different materials to see if they create a healthy mix:
- Select Material 1: Choose your first ingredient (e.g., a bucket of Kitchen Scraps).
- Enter Weight: Estimate the pounds. (A 5-gallon bucket of scraps weighs roughly 20-30 lbs).
- Select Material 2: Choose your second ingredient (e.g., Dry Leaves).
- Analyze Balance: The tool calculates the weighted chemical ratio. The visual gauge will tell you if you are in the “Sweet Spot” (30:1) or if you need to add more of one side.
Why We Built This (The “Secret Sauce”)
Simply mixing “half and half” doesn’t work because materials have vastly different densities.
The Density Problem: 5 lbs of Coffee Grounds is a small bag. 5 lbs of Dry Leaves is three giant garbage bags.
The Calculation: Our tool uses a “Harmonic Mean” calculation. It accounts for the fact that “Greens” (Nitrogen sources) are much heavier and denser than “Browns” (Carbon sources). This prevents the common mistake of adding too much heavy green material.
Educational Guide: Browns vs. Greens
To master composting, you only need to categorize your waste into two colors.
1. The Greens (Nitrogen)
These are wet, heavy, and rot quickly. They provide the protein for the bacteria to reproduce.
Examples: Grass clippings, vegetable peels, coffee grounds, chicken manure.
Warning: Too many greens create ammonia (stinky smell) and anaerobic slime.
2. The Browns (Carbon)
These are dry, light, and rot slowly. They provide the energy (carbohydrates) for the bacteria.
Examples: Fall leaves, cardboard, sawdust, straw, pine needles.
Warning: Too many browns result in a “cold pile” that takes 12-18 months to break down. If you want faster compost, check our guide on hot composting methods.
3. The Golden Rule
By volume, you usually need 2 to 3 times more Browns than Greens. This is because browns are fluffy and airy. Our calculator does the weight math for you, but visually, aim for a pile that looks mostly brown with green mixed in.
Frequently Asked Questions
Can I compost meat or dairy?
Generally, no. While meat and dairy are “Greens” (high nitrogen), they attract rats and pests and can harbor pathogens. Stick to plant-based scraps unless you are using a sealed, specialized digester like a Bokashi bucket.
Why does my compost smell like rotten eggs?
This means your pile has gone anaerobic (no oxygen). It is likely too wet and has too many Greens. To fix it, turn the pile with a pitchfork to let air in and mix in a large amount of Browns (cardboard or leaves) to absorb the moisture.
Is sawdust good for compost?
Yes, but use it sparingly. Sawdust has an incredibly high Carbon ratio (300:1 to 500:1). If you dump a whole bag of sawdust in, you will need a huge amount of Nitrogen (like chicken manure) to balance it out, or it will lock up nutrients for a long time.
