Compost Calculator
Check whether your compost has the right balance of "green" and "brown" material, based on weight.
How to use the compost calculator
- Enter the amount of "green" material you have — kitchen scraps, grass clippings or fresh garden waste.
- Enter the amount of "brown" material you have — leaves, twigs, paper or cardboard.
- The calculator shows the ratio between them, and whether the balance is good.
How the balance is calculated
"Green" material is nitrogen-rich and gives the compost nutrients and moisture — examples are kitchen scraps, grass clippings and fresh garden waste. "Brown" material is carbon-rich and gives structure and airflow — examples are dried leaves, twigs, paper and cardboard.
A common rule of thumb is to aim for roughly 1 part green to 3 parts brown (by weight). The right balance gives faster breakdown and reduces the risk of the compost smelling bad or becoming soggy and anaerobic.
Frequently asked questions
What counts as "green" and "brown" in composting?
"Green" is nitrogen-rich material like kitchen scraps, grass clippings and fresh garden waste. "Brown" is carbon-rich material like dried leaves, twigs, straw, paper and cardboard.
Why does my compost smell bad?
Bad odor usually comes from too much green/wet material relative to brown, which causes poor airflow and anaerobic breakdown. Add more brown material and turn the compost to aerate it.
How long does it take for compost to be ready?
It varies a lot, but typical home composting takes about 6–12 months, depending on balance, size, temperature and how often it's turned.