Composting Impact Calculator
Estimate the annual fertilizer savings and landfill methane avoided by composting your food and yard waste. Use it to quantify the environmental and financial benefits before starting a backyard or vermicomposting program.
About this calculator
When organic waste goes to landfill it decomposes anaerobically, producing methane — a greenhouse gas 28× more potent than CO₂ over 100 years. Composting diverts that waste to aerobic decomposition and produces usable fertilizer. The savings formula is: Annual Fertilizer Savings ($) = round(((foodWaste + yardWaste) × 52 × compostMethod × 0.3 × fertilizerPrice / 50) × 100) / 100. Here, (foodWaste + yardWaste) × 52 gives total annual waste in pounds. Multiplying by compostMethod (an efficiency factor between 0 and 1 representing the method's diversion rate) and 0.3 accounts for the fact that roughly 30% of compostable waste converts to finished compost by weight after moisture loss. Dividing by 50 converts pounds of compost to equivalent 50-lb fertilizer bags, and multiplying by fertilizerPrice gives the annual dollar value of commercial fertilizer replaced.
How to use
Assume a household generates 5 lbs of food waste and 10 lbs of yard waste per week, uses a backyard bin (compostMethod = 0.9), and commercial fertilizer costs $18 per 50-lb bag. Total weekly waste: 5 + 10 = 15 lbs. Annual waste: 15 × 52 = 780 lbs. Apply method efficiency: 780 × 0.9 = 702 lbs diverted. Finished compost: 702 × 0.3 = 210.6 lbs. Bags equivalent: 210.6 / 50 = 4.21 bags. Annual savings: 4.21 × $18 = $75.83. You'd also avoid sending 780 lbs of organic material to a methane-generating landfill each year.
Frequently asked questions
How does composting method affect the efficiency and quality of finished compost?
Composting method determines both how quickly organic matter breaks down and how much usable compost is ultimately produced. Hot composting (actively turned backyard bins maintained at 130–160°F) is the most efficient, breaking down material in 4–8 weeks and achieving diversion efficiencies above 85%. Cold or passive composting takes 6–12 months but requires almost no effort. Vermicomposting (using red wiggler worms) is highly efficient for food scraps and produces exceptionally nutrient-rich castings but handles yard waste poorly. Bokashi fermentation is fast but produces a pre-compost that still needs to be buried or processed further.
How much methane does composting actually prevent compared to landfilling?
When food waste decomposes in a landfill, it produces landfill gas that is roughly 50% methane — a potent greenhouse gas. The EPA estimates that one ton of food waste in a landfill generates approximately 0.52 metric tons of CO₂-equivalent methane emissions over its decomposition lifetime. By composting that same ton aerobically, methane production is almost entirely eliminated; aerobic decomposition releases CO₂, which is part of the short-term biogenic carbon cycle and does not accumulate in the atmosphere the way fossil methane does. For an average household diverting 400+ lbs of food waste per year, composting can prevent the equivalent of 100–200 lbs of CO₂-equivalent emissions annually.
What types of waste can and cannot be composted in a backyard bin?
Backyard composting works well with fruit and vegetable scraps, coffee grounds, tea bags, eggshells, grass clippings, leaves, small branches, and cardboard. These 'greens' (nitrogen-rich) and 'browns' (carbon-rich) should be mixed at roughly a 1:3 ratio by volume for best results. Items that should not go in a backyard bin include meat, fish, dairy, and oily foods (which attract pests and cause odors), pet feces (which may contain pathogens), and treated or painted wood. Diseased plants should also be kept out to avoid spreading pathogens back into the garden when finished compost is applied.