Weekly Food Carbon Calculator
Estimate annual CO₂ emissions from your diet based on weekly servings of meat, dairy, and vegetables, adjusted for the percentage of locally sourced food. Returns kilograms of CO₂ per year.
Last updated: May 2026
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About this calculator
The formula is Annual CO₂ (kg) = ((meat × 2.5 + dairy × 0.9 + vegetables × 0.3) × (1 − local/100 × 0.2)) × 52, where the per-serving CO₂ values are kg CO₂-equivalent per serving (meat 2.5, dairy 0.9, vegetables 0.3), 'local' is the percentage of locally sourced food (0–100), and ×52 converts weekly emissions to annual. Local sourcing reduces total food emissions by up to 20% at 100% local — the multiplier (1 − local/100 × 0.2) ranges from 1.0 at 0% local to 0.8 at 100% local. The category averages aggregate diverse foods: 'meat' covers beef (~27 kg CO₂/kg, very high), chicken (~6 kg/kg, much lower), and pork (~12 kg/kg); 'dairy' covers milk (~1.4 kg/L) through cheese (~21 kg/kg). The 2.5 kg/serving meat figure assumes mixed consumption averaging ~150 g/serving. Edge cases: the local-source reduction is conservative — peer-reviewed analyses (Poore & Nemecek 2018, Science) show transportation accounts for only ~6% of food emissions on average, with land-use change, methane from cattle, and fertiliser dominating. The formula's 20% cap may overstate the benefit of buying local for emissions specifically (though local food has other ecological and economic merits). The result excludes food waste, which adds another 20–30% to true 'consumed' emissions in most Western diets. It also doesn't model dietary substitution (a beef-heavy diet at 7 'meat servings' has dramatically higher emissions than a chicken-only diet at 7 servings).
How to use
Example 1 — typical Western omnivore diet. Meat 10 servings/week, dairy 14 servings/week, vegetables 21 servings/week, 30% local. Step 1: weekly base = 10 × 2.5 + 14 × 0.9 + 21 × 0.3 = 25 + 12.6 + 6.3 = 43.9 kg. Step 2: local adjustment = 1 − 30/100 × 0.2 = 1 − 0.06 = 0.94. Step 3: adjusted weekly = 43.9 × 0.94 = 41.27 kg. Step 4: annual = 41.27 × 52 ≈ 2,146 kg. Verify: typical Western diets emit around 2–3 tonnes CO₂/year, with meat-heavy diets at the upper end; 2.1 tonnes for moderate meat consumption is consistent ✓. Example 2 — plant-based diet. Meat 0 servings, dairy 3 servings (occasional cheese), vegetables 35 servings, 60% local. Step 1: weekly base = 0 + 3 × 0.9 + 35 × 0.3 = 0 + 2.7 + 10.5 = 13.2 kg. Step 2: local adjustment = 1 − 60/100 × 0.2 = 1 − 0.12 = 0.88. Step 3: adjusted weekly = 13.2 × 0.88 = 11.62 kg. Step 4: annual = 11.62 × 52 ≈ 604 kg. Verify: a mostly plant-based diet typically emits 0.5–1.2 tonnes CO₂/year, so 0.6 tonnes is in the realistic range ✓. Switching from the omnivore example to this plant-based pattern saves ~1.5 tonnes/year — comparable to skipping one long-haul flight or driving 7,000 km less in a typical car.
Frequently asked questions
Why is beef so much more carbon-intensive than other foods?
Beef has the highest carbon footprint of any common food at ~27 kg CO₂-equivalent per kg of meat, primarily because cattle are ruminants that produce methane (a greenhouse gas ~28× more potent than CO₂ over 100 years) through enteric fermentation in their digestive systems. Additionally, beef production requires large amounts of feed, which requires land that is often cleared from forests (releasing stored carbon) and water; the global average is about 25 kg of feed and 15,000 litres of water per kg of beef. Other meats are much lower: chicken ~6 kg CO₂/kg, pork ~12 kg/kg, fish 1–10 kg/kg depending on species (farmed salmon ~5, wild tuna higher). Plant proteins are dramatically lower: tofu ~3 kg/kg, beans ~1 kg/kg, peas ~0.5 kg/kg. The 2.5 kg/serving figure in this calculator is a mixed-meat average; if your meat consumption is mostly beef, multiply by roughly 2; if mostly chicken, multiply by roughly 0.5 for a more accurate estimate.
How much does buying local actually reduce food emissions?
Less than most people expect. Peer-reviewed analyses (most notably Poore & Nemecek 2018, Science) show that transportation accounts for only ~6% of total food emissions on average, with the biggest impacts being land-use change, methane from livestock, and fertiliser production. For most foods, what you eat matters far more than how far it travelled. The exceptions are air-freighted foods (fresh out-of-season berries, asparagus, some seafood) which can have 10× the transport emissions of sea-freighted equivalents — air freight is rare for food, but when it happens it dominates. Hothouse-grown local vegetables (greenhouse tomatoes in winter in northern Europe) can also have higher emissions than out-of-season imports from regions with milder climates. The 20% cap this calculator uses for 100% local sourcing is generous and includes broader effects like reduced packaging, freshness, and seasonal eating. Local food has other genuine merits — supporting local farms, food security, freshness, ecosystem services — but for raw carbon accounting, switching from beef to chicken outweighs going 100% local many times over.
Does this calculator account for food waste?
No — the formula counts only the emissions of food you eat, not food that is purchased and discarded. In typical Western households, 20–30% of food bought ends up wasted, either at home (forgotten in fridges, plate scraping) or in the supply chain. Including waste would mean multiplying total food emissions by roughly 1.25–1.4, depending on country. Reducing waste is one of the most impactful actions an individual can take: a UK household that wastes typical amounts could save ~600 kg CO₂/year by simply eating what they buy. Best-by date confusion is a major contributor — dates on packaging are mostly conservative quality estimates, not safety cutoffs, and using your senses to evaluate food is usually safe. To account for waste manually, multiply this calculator's output by 1 + (waste percentage / 100); for the average Western household, multiplying by 1.25 gives a more accurate true-impact figure.
What are the common mistakes when estimating food emissions?
The biggest mistake is treating all 'meat' as equivalent — beef has 4–5× the emissions of chicken, so a 'reduce meat' goal that just swaps beef for chicken saves more than 'reduce overall calories'. The second is overestimating the impact of local sourcing — see the dedicated FAQ above; what you eat matters more than where it came from. The third is ignoring dairy: cheese (~21 kg CO₂/kg) and butter (~12 kg/kg) are among the highest-emission foods, comparable to pork; the 0.9 kg/serving average in this calculator covers milk-heavy dairy patterns, but cheese-heavy diets are much higher. People also forget that highly processed foods (snacks, soft drinks, ready meals) have additional emissions from manufacturing, refrigeration, and packaging not captured here — roughly 10–30% beyond raw-ingredient emissions. Drinking water from the tap rather than bottled saves several hundred kg/year. Finally, eating-out emissions tend to be 20–40% higher per equivalent meal than home cooking due to portion size, kitchen energy use, and waste — restaurant meals aren't trivially equivalent to home meals.
When should I not use this calculator?
Do not use it for detailed nutritional or environmental life-cycle assessments — this is a coarse heuristic with three food categories, while real diets span dozens of foods with widely varying emission profiles (beef vs chicken vs fish vs tofu all collapsed into 'meat'). Use a tool like Eat-Lancet or a peer-reviewed LCA database (Poore & Nemecek 2018, IPCC AR6 food chapter) for serious analysis. It is not appropriate for children, athletes, or anyone with non-standard caloric requirements; serving counts mean different things for different bodies. Do not use it for restaurant or catering operations — those have additional waste, refrigeration, and energy overhead that residential averages don't capture. It is not suitable for vegan diets without modification — the formula assumes some animal products and may overestimate emissions for fully plant-based eaters. Finally, do not use it to claim carbon neutrality from dietary changes without including the offsetting actions (rewilding land you'd previously support, etc.) and verifying with a more rigorous tool; this calculator is a starting point for awareness, not an audit-grade emissions report.