Food Waste Calculator
Food waste is one of the most significant and overlooked household expenses and environmental impacts. The USDA estimates that US households waste roughly 30 to 40 percent of the food they buy, which translates to hundreds of dollars per household per year in wasted grocery spending. Beyond the financial cost, food waste in landfills produces methane, a potent greenhouse gas. The EPA estimates that food waste in landfill generates approximately 2.0 kg CO2e per kilogram of food discarded, accounting for both the methane from decomposition and the embedded carbon in producing and transporting the food. This calculator takes three inputs: your weekly food waste in pounds, your weekly grocery spend in dollars, and the percentage of your grocery spend you estimate is wasted (the USDA default is 30 percent). It outputs your annual cost of wasted food, annual CO2e from that waste, and the potential savings from cutting waste by 50 percent. It also converts your CO2e to a tree-equivalent using the US Forest Service estimate of 21.7 kg CO2 absorbed per tree per year, giving you an intuitive sense of the offset required. The lbs to kg conversion is 1 lb = 0.4536 kg.
Your food waste costs approximately -- per year and produces -- kg CO2e.
How this calculator works
Weekly food waste in pounds is annualised, converted to kg, and multiplied by the EPA CO2e factor. The cost of wasted food is calculated from your grocery spend and waste percentage.
Annual waste (lbs) = weekly waste lbs × 52
Annual waste (kg) = annual waste lbs × 0.4536
Annual CO2e (kg) = annual waste kg × 2.0
Annual wasted cost ($) = weekly spend × (waste pct / 100) × 52
50% reduction savings (cost) = annual wasted cost × 0.5
50% reduction CO2e saved (kg) = annual CO2e × 0.5
Tree-years = annual CO2e / 21.7 kg CO2 per tree per year
Worked example (default inputs)
- Annual waste: 4 lbs/wk × 52 = 208.00 lbs/year
- Annual waste in kg: 208.00 × 0.4536 = 94.35 kg/year
- Annual CO2e: 94.35 × 2.0 = 188.70 kg CO2e/year
- Annual wasted cost: $200/wk × 30% × 52 = $3,120.00/year
- 50% reduction saves: $3,120.00 × 0.5 = $1,560.00/year and 94.35 kg CO2e
- Tree-years to offset: 188.70 / 21.7 = 8.70 trees/year
Why food waste matters
| Statistic | Figure | Source |
|---|---|---|
| Share of US food supply wasted | 30 to 40% | USDA Economic Research Service |
| Annual US food waste by weight | ~133 billion lbs | USDA Economic Research Service |
| Annual US food waste value | ~$161 billion | USDA Economic Research Service |
| CO2e from food waste in landfill | 2.0 kg CO2e per kg waste | EPA Sustainable Management of Food |
| CO2 absorbed per tree per year (US avg) | 21.7 kg CO2/tree/year | US Forest Service |
Food waste is the single largest category of material entering US landfills and represents the largest source of US methane emissions from the waste sector. Reducing food waste by 50 percent is a joint USDA/EPA goal under the US Food Waste Challenge.
How to reduce food waste at home
- Meal plan before shopping. Buying only what you need and will use within a week is the most direct way to reduce waste.
- Store food correctly. Many foods last significantly longer with proper storage: whole fruits on the counter, cut fruit in airtight containers, herbs stored upright in water in the fridge.
- Use the FIFO method. Place newly bought food behind older food in the fridge and pantry so older items get used first.
- Understand date labels. "Best by" and "sell by" dates indicate peak quality, not safety. Most foods are safe to eat past these dates if stored correctly. "Use by" on perishables like meat is a safety date.
- Compost scraps. Food scraps that cannot be consumed (vegetable peels, coffee grounds, eggshells) can be composted rather than landfilled, eliminating the methane contribution.
- Donate surplus food. Unexpired non-perishables and fresh food that you will not use can be donated to local food banks. Visit Feeding America to find your nearest food bank.
Food waste calculator: frequently asked questions
How much food does the average US household waste?
The USDA Economic Research Service estimates that American households waste approximately 30 to 40 percent of the food supply, representing about 133 billion pounds and $161 billion worth of food annually. At the household level, this translates to roughly 20 to 30 percent of groceries purchased being thrown away. The USDA and EPA's joint food waste reduction goal calls for a 50 percent reduction in US food loss and waste by 2030 compared to 2010 levels.
What are the environmental impacts of food waste in landfills?
When food decomposes in a landfill, it produces methane, a greenhouse gas approximately 28 times more potent than CO2 over 100 years. The EPA estimates that food in US landfills produces the equivalent of about 2.0 kg CO2e per kg of food waste, accounting for both direct methane emissions and the upstream emissions embedded in producing and transporting the food that was wasted. Food waste is the single largest category of material entering US landfills, making it a significant target for both climate and cost reduction.
How does the waste percentage of grocery spend work?
The waste percentage input represents the share of your grocery spending that goes to food you ultimately throw away (or that spoils before use). The USDA average estimate is about 30 percent. If you spend $200 per week on groceries and waste 30 percent, that is $60 per week or $3,120 per year in food that was purchased but not consumed. You can lower this estimate if you meal-plan carefully, or raise it if you regularly throw away significant quantities of fresh produce, leftovers, or prepared food.
What is the tree equivalent for CO2 absorption?
The US Forest Service estimates that an average US tree absorbs approximately 21.7 kg of CO2 per year. This figure varies widely depending on tree species, age, size, and climate, but 21.7 kg/tree/year is the commonly cited US average used by the EPA for public communication purposes. In this calculator, the tree equivalent for your food waste CO2e is calculated by dividing your annual CO2e by 21.7, giving you a rough sense of how many tree-years of carbon absorption are needed to offset your food waste emissions.
What are the most effective ways to reduce food waste at home?
The EPA and USDA recommend: meal planning before grocery shopping to buy only what you will use; storing food correctly (correct temperature, airtight containers) to extend shelf life; understanding the difference between 'best by' and 'use by' dates (most foods are safe to eat past 'best by' dates, which indicate peak quality not safety); using the FIFO method (first in, first out) in your refrigerator and pantry; composting food scraps that cannot be avoided; and donating surplus non-perishable food to food banks.
Official sources
- USDA Economic Research Service, food waste: usda.gov/foodwaste/faqs.
- EPA Sustainable Management of Food: epa.gov/sustainable-management-food.
- US Forest Service, urban tree CO2 absorption: fs.usda.gov.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology. Estimates based on USDA and EPA national averages; individual results will vary.