Compost Ratio Calculator
Balance greens and browns for fast compost.
Enter your values
Enter the greens in kg.
Enter the greens c:n you are working with.
Enter the browns in kg.
Enter the browns c:n you are working with.
Enter the target c:n you are working with.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Current C:N ratio
- 45:1
- Verdict
- Too much brown — add greens
- Browns for target
- 10 kg
- Total pile mass
- 60 kg
Quick answer
Compost breaks down fastest at a carbon to nitrogen ratio near 30:1.
C:N = Σ(mass × C:N) ÷ Σmass
At a glance
| What it does | Balance greens and browns for fast compost. |
|---|---|
| Category | Science |
| Inputs needed | Greens, Greens C:N, Browns, Browns C:N, Target C:N |
| Main output | Current C:N ratio |
| Formula | C:N = Σ(mass × C:N) ÷ Σmass |
| Cost | Free — no sign-up, no download |
How to use the Compost Ratio Calculator
- 1Weigh your greens and browns.
- 2Use typical C:N values or look up your materials.
- 3Adjust until the ratio sits near 30:1.
Inputs explained
- Greens(kg)
- Enter the greens in kg.
- Greens C:N
- Enter the greens c:n you are working with.
- Browns(kg)
- Enter the browns in kg.
- Browns C:N
- Enter the browns c:n you are working with.
- Target C:N
- Enter the target c:n you are working with.
Worked example
Using the values the calculator loads with:
Inputs
- Greens20 kg
- Greens C:N15
- Browns40 kg
- Browns C:N60
- Target C:N30
Results
- Current C:N ratio45:1
- VerdictToo much brown — add greens
- Browns for target10 kg
- Total pile mass60 kg
Frequently asked questions
What counts as greens?
Grass clippings, food scraps and manure.
Why does my pile smell?
Too many greens and not enough air — add browns and turn it.
What do I need to enter into the Compost Ratio Calculator?
Just 5 values: greens, greens c:n, browns, browns c:n, target c:n. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Compost Ratio Calculator work out the answer?
Compost breaks down fastest at a carbon to nitrogen ratio near 30:1. It applies the formula C:N = Σ(mass × C:N) ÷ Σmass and shows the working so you can check each step by hand.
Is the Compost Ratio Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.