Eggs
One dozen large eggs represents approximately:
What this means
The water value above is direct water use, not a full lifecycle water footprint; the functional unit and system boundary define what the values mean. Feed-related water and water-scarcity metrics may produce different values depending on the source and boundary. For meat from the same animal, see chicken.
Formal measurement basis
| Item measured | Chicken eggs |
|---|---|
| Formal functional unit | One dozen large eggs, approximately 680 g shelled eggs |
| Literature-normalized unit | 1 kg shelled eggs where source data is reported per kg |
| Primary boundary | Cradle-to-farm-gate or cradle-to-processing-gate depending on source |
| Secondary boundary | Feed production and laying operation |
| Source review | Version 2 source review, 2026 |
Full measurement table
| Physical quantity | Working value | Literature range | Unit | Boundary note |
|---|---|---|---|---|
| GHG emissions, selected U.S. working boundary | 2.1 | 1.5–4.7 | kg CO₂e / kg egg | Selected Version 2 working range; GWP100 basis where source supports it |
| GHG emissions, broader farm-system context | Not used as working value | 2.6–8.4 | kg CO₂e / kg egg | Different farm-system or boundary context; shown only as context, not mixed into the working range |
| GHG emissions, one dozen large eggs | ~3.15 | ~2.25–7.05 | lb CO₂e / dozen large eggs | Based on 24 oz / 680 g per dozen large eggs |
| Feed input | 3.44 | Range pending hardening | lb feed / lb egg | U.S. 2010 egg production summary; data vintage should be refreshed or retained explicitly |
| Feed input, one dozen large eggs | ~5.16 | Range pending hardening | lb feed / dozen large eggs | Converted from 1.5 lb egg mass |
| Direct water use | ~4.5 | Range pending hardening | gallons / dozen eggs | Direct water only, not full lifecycle water footprint |
| Lifecycle water / water scarcity | Not selected | Boundary pending | varies | Requires source hardening |
What is included
The GHG and feed values are based on egg-production LCA literature and U.S. egg-industry summary data. The direct-water value refers only to direct water use per dozen eggs.
What is excluded
- Cooking
- Household refrigeration after purchase unless a source explicitly includes it
- Household waste
- Nutrition claims
- Dollar conversion of environmental effects
- Full lifecycle water claims based only on direct-water data
Why values vary
Egg values vary by feed composition, housing system, electricity source, hen productivity, manure management, allocation method, and whether the boundary stops at the farm, processing facility, retail, or household.
Source notes
The GHG value is a Version 2 working value based on U.S. egg-production LCA reporting and should be hardened against the original Pelletier et al. paper. The direct-water and feed values come from the Egg Industry Center summary and should remain labeled with their exact boundaries. The feed-input figure uses a 2010 production basis; either a newer source should replace it or the vintage should remain explicit.
Sources
- Pelletier, Ibarburu, and Xin, Comparison of the Environmental Footprint of the Egg Industry in the United States in 1960 and 2010, Poultry Science, 2014. Used for: U.S. egg-production LCA boundary and impact drivers.
- Egg Industry Center, A Comparative Assessment of the Environmental Footprint of the U.S. Egg Industry. Used for: feed input and direct-water values per dozen eggs.
- USDA Agricultural Marketing Service, United States Standards, Grades, and Weight Classes for Shell Eggs. Used for: one dozen large eggs equals 24 ounces minimum net weight.
- NORSUS, Life Cycle Assessment of Meat and Egg. Used for: modern egg LCA cross-check and range context.