Enter your composting method, choose your unit of measure, then add up to three materials and their weights to calculate your pile's C:N ratio. You'll get an assessment of your mix alongside total weight, total carbon, and total nitrogen — so you know exactly whether your compost is balanced or needs tweaking.
C:N Ratio
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Assessment
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Total Weight
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Total Carbon
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Total Nitrogen
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The C:N ratio is the balance between carbon-rich 'brown' materials and nitrogen-rich 'green' materials in your compost. It's essential for proper decomposition and preventing odors.
For traditional composting, aim for a C:N ratio of 25-30:1. For vermicomposting (worm bins), a slightly lower ratio of 20-25:1 works best since worms prefer less carbon-heavy mixtures.
No, you don't need to be perfectly precise. Getting roughly in the right range is sufficient. Your compost will still work with ratios between 20:1 and 40:1, though it may decompose slower or faster.
A high C:N ratio (too much carbon/browns) will slow down decomposition significantly. Your compost pile will take much longer to break down, but it won't smell bad or attract pests.
A low C:N ratio (too much nitrogen/greens) will cause your compost to become slimy, smelly, and anaerobic. You'll notice ammonia odors and possible pest problems.
Brown materials include dry leaves, cardboard, newspaper, sawdust, straw, and wood chips. These materials are typically dry and provide the carbon needed for composting.
Green materials include kitchen scraps, grass clippings, coffee grounds, and fresh manure. These materials are usually moist and provide the nitrogen needed for microbial activity.
If your ratio is too high (too much carbon), add more greens like kitchen scraps or grass clippings. If it's too low (too much nitrogen), add more browns like dry leaves or shredded paper.