Food · emission factor
The Carbon Footprint of Eggs
450 g CO₂e / 100g
Eggs produce roughly 450 g of CO₂-equivalent per 100 g — about 4.5 kg CO₂e per kilogram, or around 25 g per medium egg's edible portion. That makes them one of the lowest-impact animal proteins available: less than a sixth of beef's footprint per 100 g and well below cheese. Understanding where those emissions come from helps explain why eggs are often recommended as a climate-friendlier protein swap.
Why eggs have a relatively low footprint
Most of an egg's climate impact comes from hen feed. Growing, processing, and transporting grain and soy for layer hens accounts for the majority of emissions, with additional contributions from manure management (which releases nitrous oxide and some methane), on-farm energy use, and land-use change linked to feed crops such as soy. Crucially, hens are not ruminants: unlike cattle and sheep, they do not produce methane through enteric fermentation, which is the main reason beef sits at 2,990 g CO₂e per 100 g while eggs sit at 450 g. Laying hens are also highly efficient converters of feed into protein — a hen can lay around 300 eggs a year — so relatively little feed and land is needed per gram of protein delivered.
How eggs compare to other proteins
At 450 g CO₂e per 100 g, eggs land in the middle-lower band of protein sources. They beat chicken meat (620 g), fish (550 g), pork (1,220 g), and are dramatically lower than cheese (1,350 g), lamb (2,420 g), and beef (2,990 g). Plant proteins still win outright: tofu comes in at 200 g and beans at just 100 g per 100 g. Per gram of protein, eggs perform respectably because they are protein-dense (about 12–13 g protein per 100 g). For context, livestock overall accounts for roughly 14–15% of global greenhouse gas emissions according to the FAO — and poultry and eggs are consistently the smallest contributors within that sector.
What changes the number
The 450 g figure, based on the global meta-analysis by Poore and Nemecek (2018, Science), is an average across production systems — individual farms vary. Feed composition matters most: soy linked to deforestation raises the footprint, while locally sourced or by-product feed lowers it. Housing systems differ less than many assume; free-range hens can have slightly higher emissions per egg because they use marginally more feed, though differences are small compared with the gap between eggs and red meat. Packaging and transport are minor contributors, since eggs are usually produced and consumed within the same region. Food waste is the lever consumers control directly — a wasted egg carries its full production footprint for nothing.
How eggs compares
How to reduce this footprint
- ✓ Swap eggs in for red meat or cheese in a few meals a week — replacing 100 g of beef with eggs saves around 2.5 kg CO₂e.
- ✓ Buy only what you'll use and store eggs properly; a wasted egg wastes its entire footprint.
- ✓ Look for eggs from farms using deforestation-free or locally sourced feed, since feed drives most emissions.
- ✓ Track your meals for a couple of weeks in an app like Decarbonr to see how protein choices actually shape your food footprint.
Frequently asked questions
Are eggs bad for the environment?
Compared with other animal proteins, no. At about 450 g CO₂e per 100 g, eggs emit less than chicken, fish, pork, cheese, lamb, and beef. Only plant proteins like beans (100 g) and tofu (200 g) do meaningfully better.
What is the carbon footprint of one egg?
A medium egg's edible portion (roughly 50 g) accounts for about 225 g CO₂e, based on the average of 450 g per 100 g. That's comparable to driving about 1 km in a petrol car (231 g CO₂e per km).
Why do eggs emit so much less CO₂ than beef?
Hens don't produce methane through digestion the way cattle do, and they convert feed into protein far more efficiently, needing much less land and grain. The result is 450 g CO₂e per 100 g for eggs versus 2,990 g for beef — more than a sixfold difference.
Track this automatically
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Sources & methodology: see Research & scientific references. Figures are averages used by the Decarbonr app; real-world values vary by production system, country, and occupancy.