How does this calculate compost ratios?

It estimates the ideal carbon-to-nitrogen (C:N) ratio of your "brown" (carbon-rich) and "green" (nitrogen-rich) materials, targeting roughly 25-30:1 for efficient composting.

What counts as "brown" versus "green" material?

Browns include dry leaves, straw, and cardboard (high carbon); greens include fresh grass clippings, food scraps, and coffee grounds (high nitrogen).

Why does the carbon-to-nitrogen ratio matter?

Too much nitrogen makes compost smelly and slimy; too much carbon slows decomposition drastically. The right balance speeds up breakdown and reduces odor.

Compost Calculator - CalculatorLabs.net

Compost Calculator

Check whether your compost pile has a healthy green-to-brown ratio.

Green Material Volume (cu ft) — food scraps, grass

Brown Material Volume (cu ft) — leaves, straw, cardboard

Brown-to-Green Ratio -

Pile Balance -

Estimated Finished Compost Volume -

What Is the Compost Calculator?

The Compost Calculator checks whether the mix of nitrogen-rich “green” material and carbon-rich “brown” material in your compost pile is in a healthy range, which speeds up decomposition and avoids odor problems.

Formula Used

Ratio = Brown Volume ÷ Green Volume (ideal ≈ 2:1 to 4:1 by volume)

Greens (food scraps, grass clippings, coffee grounds) are nitrogen-rich; browns (dry leaves, straw, cardboard) are carbon-rich. Finished compost volume is typically estimated at about half the original combined volume after breakdown.

How to Use This Calculator

Estimate the volume of green material you're adding, in cubic feet.
Estimate the volume of brown material you're adding, in cubic feet.
Click Calculate to see your ratio and whether it's balanced.

Worked Example

With 2 cu ft of greens and 6 cu ft of browns, the ratio is 6÷2 = 3:1, which is right in the healthy 2:1 to 4:1 range. The combined 8 cu ft of raw material will shrink to roughly 4 cu ft of finished compost.