Vegan Footprint Calculator
Compare your current diet's carbon footprint against a vegan diet, and see how many vegan days a week saves how much CO2e.
🥦 What is a Vegan Footprint Calculation?
A vegan footprint calculation compares your normal diet's greenhouse gas footprint against a vegan diet, using published daily CO2e figures for six diet categories ranging from high meat-eater to vegan, and lets you model eating vegan on some days of the week rather than treating it as an all-or-nothing switch. Each diet's footprint reflects everything eaten across a standardized 2000 kcal day, based on a large-scale UK cohort study that linked real dietary survey data to greenhouse gas emissions factors for every food category.
The gap between diet categories is substantial and largest at the meat-heavy end of the scale. A high meat-eater's diet at roughly 7.19 kg CO2e a day sits well above a vegan diet's roughly 2.89 kg a day, close to a 60 percent difference. But the categories are not evenly spaced. The step from high meat to medium meat saves more per day than the step from vegetarian to vegan, since dairy and eggs, which remain in a vegetarian diet, carry a real but smaller footprint than meat.
People use this calculation to model partial changes realistically, since full dietary switches are hard to sustain for many people while a few vegan days a week is a much more common and achievable pattern. Health-conscious households, "Meatless Monday" style programs, and anyone curious what a single day's dietary choice is worth in carbon terms use this blended approach to see a number that matches how they actually plan to eat, not an idealized all-vegan scenario.
One caveat matters: this is a carbon-only comparison. Nutritional needs, food access, cost and personal preference all shape real dietary decisions, and a carbon figure alone cannot make that decision for anyone. Use this calculator to understand the scale of the carbon tradeoff, not as a complete guide to what to eat.
📐 Formula
📖 How to Use This Calculator
Steps
💡 Example Calculations
Example 1 — High Meat-Eater Going Vegan 2 Days a Week
High meat-eater diet, 2 vegan days a week
Example 2 — Medium Meat-Eater Going Fully Vegan
Medium meat-eater diet, 7 vegan days a week
Example 3 — Vegetarian Adding 3 Vegan Days
Vegetarian diet, 3 vegan days a week
❓ Frequently Asked Questions
🔗 Related Calculators
How much CO2 does a vegan diet save compared to a meat diet?
Against a high meat-eater's diet at roughly 7.19 kg CO2e a day, a vegan diet at roughly 2.89 kg CO2e a day saves about 4.3 kg a day, or around 1,569 kg CO2e a year, close to a 60% reduction, following the Scarborough et al. 2014 UK dietary emissions study.
Do I need to be fully vegan to reduce my footprint?
No. This calculator models eating a vegan diet on a chosen number of days each week, blended with your normal diet on the rest, so even 1 or 2 vegan days a week produces a proportional reduction without requiring a full switch.
What is the blended footprint formula?
Blended annual CO2e equals your current diet's daily footprint times the non-vegan days, plus the vegan diet's daily footprint times the vegan days, divided by 7, then multiplied by 365. Written out: E_blend = ((C_current times (7 minus d)) plus (C_vegan times d)) divided by 7, times 365.
What is the carbon footprint of a vegetarian diet?
A vegetarian diet averages roughly 3.81 kg CO2e a day in the Scarborough et al. dataset, close to but slightly above a fish-eater's diet at roughly 3.91 kg and meaningfully above a fully vegan diet at roughly 2.89 kg a day, since dairy and eggs still contribute a real footprint.
Which diet change gives the biggest carbon saving for the smallest sacrifice?
Moving from high meat-eating toward medium or low meat-eating typically gives a larger absolute saving per step than moving from vegetarian to vegan, since the daily footprint gaps between meat-eating categories are wider than the gap between vegetarian and vegan.
Is fish a low-carbon alternative to meat?
Relatively, yes. A fish-eater's diet averages roughly 3.91 kg CO2e a day, well below any meat-eating category and close to vegetarian, though still above a fully vegan diet. Fish footprint varies considerably by species and catch or farming method.
How was this data collected?
Scarborough et al. 2014 analysed dietary data from over 55,000 participants in the EPIC-Oxford cohort study, linking self-reported food intake to greenhouse gas emissions factors for each food category, then adjusting results to a standard 2000 kcal daily intake for fair comparison.
Does this calculator include food waste or transport?
The underlying Scarborough et al. figures are consumption-based averages that implicitly reflect typical UK food waste and supply chain patterns at the time of the study, but this calculator does not let you adjust for your own specific waste or sourcing behavior.
How much does 2 vegan days a week save over a year?
It depends on your starting diet. For a high meat-eater switching to vegan for 2 days a week, this calculator computes roughly 448 kg CO2e saved a year, about a 17% reduction, without requiring any change on the other 5 days.
Why do the diet categories differ by meat quantity rather than just meat versus no meat?
Because the footprint scales with how much meat is eaten, not simply whether any is eaten. A high meat-eater consuming over 100 g of meat a day has a substantially larger footprint than a low meat-eater under 50 g a day, even though both are technically meat-eaters.