Emission Factors Reference Table
Quick answer: An emission factor converts an activity (driving 1 km, using 1 kWh of electricity) into CO₂ equivalent. This page provides comprehensive tables of emission factors used in carbon footprint calculations, sourced from DEFRA, IPCC, and peer-reviewed research.
Transport Emission Factors
All values in kg CO₂e per passenger-kilometer unless noted.
| Mode | Emission Factor | Notes |
|---|---|---|
| Car (gasoline, average) | 0.192 kg/km | Based on average fuel economy |
| Car (diesel, average) | 0.171 kg/km | Slightly more efficient than gasoline |
| Car (hybrid) | 0.109 kg/km | ~43% less than standard gasoline |
| Car (BEV, global average grid) | 0.053 kg/km | Varies dramatically by grid (0.01–0.12) |
| Motorcycle | 0.103 kg/km | Varies by engine size |
| Bus (diesel, city) | 0.089 kg/km | Per passenger, average occupancy |
| Coach (long distance) | 0.027 kg/km | High occupancy makes it efficient |
| Train (national, diesel) | 0.041 kg/km | UK average |
| Train (national, electric) | 0.006 kg/km | Varies by grid mix |
| Subway / Metro | 0.028 kg/km | Electric urban rail average |
| Domestic flight | 0.255 kg/km | Short haul, high LTO impact |
| Long-haul flight (economy) | 0.150 kg/km | More efficient per km |
| Long-haul flight (business) | 0.430 kg/km | ~2.9x economy due to seat space |
| Ferry | 0.115 kg/km | Per passenger |
| Bicycle / Walking | 0 kg/km | Direct emissions only |
Sources: DEFRA 2024, EEA, ICAO Carbon Emissions Calculator
Food Emission Factors
All values in kg CO₂e per kg of food product (farm to fork).
| Food | Emission Factor | Key Driver |
|---|---|---|
| Beef (herd) | 60.0 kg/kg | Methane from digestion, land use |
| Lamb & Mutton | 24.0 kg/kg | Similar to beef, lower volume |
| Cheese | 21.0 kg/kg | Dairy processing intensity |
| Pork | 7.0 kg/kg | Feed production, manure |
| Poultry (chicken) | 6.0 kg/kg | Feed, energy for housing |
| Farmed Fish (salmon) | 5.0 kg/kg | Feed, energy for operations |
| Eggs | 4.5 kg/kg | Feed production |
| Rice | 4.0 kg/kg | Methane from paddy fields |
| Milk | 3.2 kg/kg | Dairy cattle methane |
| Tofu | 2.0 kg/kg | Soy processing |
| Wheat / Bread | 1.4 kg/kg | Fertilizer, farming energy |
| Tomatoes | 1.4 kg/kg | Heated greenhouses increase it |
| Beans & Lentils | 1.0 kg/kg | Nitrogen-fixing, low input |
| Root Vegetables | 0.4 kg/kg | Low-input crops |
| Apples | 0.4 kg/kg | Seasonal variation matters |
Source: Poore & Nemecek (2018), Science — meta-analysis of 38,700 farms in 119 countries
Home Energy Emission Factors
Electricity grid emission factors by country (kg CO₂e per kWh).
| Country / Grid | Emission Factor | Primary Mix |
|---|---|---|
| Global Average | 0.475 kg/kWh | Mixed fossil and renewables |
| United States | 0.386 kg/kWh | Natural gas, coal, nuclear |
| United Kingdom | 0.233 kg/kWh | Gas, wind, nuclear |
| European Union (avg) | 0.231 kg/kWh | Mixed, growing renewables |
| Germany | 0.338 kg/kWh | Coal, wind, solar |
| France | 0.056 kg/kWh | Nuclear dominant |
| Norway | 0.020 kg/kWh | Hydroelectric |
| China | 0.555 kg/kWh | Coal dominant |
| India | 0.708 kg/kWh | Coal dominant |
| Australia | 0.540 kg/kWh | Coal, growing solar |
| Japan | 0.457 kg/kWh | Natural gas, coal |
| Brazil | 0.074 kg/kWh | Hydroelectric dominant |
Sources: IEA 2024, Ember Climate, DEFRA 2024
Home Heating Emission Factors
| Fuel / System | Emission Factor | Notes |
|---|---|---|
| Natural Gas | 0.183 kg/kWh | Most common heating fuel |
| Heating Oil | 0.246 kg/kWh | Higher than gas |
| LPG | 0.214 kg/kWh | Propane/butane |
| Coal | 0.340 kg/kWh | Highest fossil fuel |
| Electricity (resistive) | Grid factor × 1.0 | Direct electric heating |
| Heat Pump (COP 3.0) | Grid factor ÷ 3.0 | 3x efficiency vs resistive |
| Wood Pellets | 0.039 kg/kWh | Considered low-carbon renewable |
Source: DEFRA 2024, IPCC AR6
Goods & Consumption Emission Factors
Per-item and spending-based emission factors.
| Category | Emission Factor | Basis |
|---|---|---|
| Cotton T-shirt | 7 kg CO₂e | Per item |
| Pair of Jeans | 33 kg CO₂e | Per item |
| Cotton Dress | 25 kg CO₂e | Per item |
| Winter Jacket (synthetic) | 70 kg CO₂e | Per item |
| Sneakers / Trainers | 14 kg CO₂e | Per pair |
| Smartphone | 70 kg CO₂e | Lifecycle, ~80% manufacturing |
| Laptop | 300 kg CO₂e | Lifecycle |
| Desktop PC | 400 kg CO₂e | Lifecycle |
| Tablet | 130 kg CO₂e | Lifecycle |
| Washing Machine | 500 kg CO₂e | Lifecycle, ~10 year use |
| Car (new, manufacturing) | 6,000–35,000 kg CO₂e | Depends on size and powertrain |
| All goods (spending-based) | 0.30 kg per $1 spent | Global average, goods only |
| All services (spending-based) | 0.10 kg per $1 spent | Services sector average |
Sources: Poore & Nemecek (2018), Berners-Lee (2020), ADEME Base Carbone, DEFRA 2024
Waste Emission Factors
| Material | Landfill (kg CO₂e/kg) | Recycling Savings |
|---|---|---|
| Food Waste | 0.58 | Composting: −0.25 |
| Paper / Cardboard | 0.59 | 70% energy savings |
| Glass | 0.26 | 30% energy savings |
| Plastic (mixed) | 0.04 | Variable, depends on type |
| Aluminum | 0.00 (inert) | 95% energy savings |
| Steel | 0.00 (inert) | 60–74% energy savings |
| Textiles | 3.27 | Reuse significantly better |
Sources: DEFRA 2024, IPCC AR6 WGIII
How Emission Factors Are Calculated
Emission factors are derived through Life Cycle Assessment (LCA) — measuring total emissions from raw material extraction through manufacturing, use, and disposal. Key considerations:
- System boundaries matter. "Farm to fork" vs "cradle to grave" give different numbers.
- Geographic variation. Grid electricity, climate, and farming practices differ by region.
- Temporal change. Factors are updated as technology and practices improve.
- CO₂e includes all GHGs. Methane (CH₄) and nitrous oxide (N₂O) are converted to CO₂ equivalent using Global Warming Potential (GWP).
For detailed methodology, see our calculation guides: Transport, Food, Housing, and Consumption.
Sources: DEFRA UK Government Conversion Factors (2024), IPCC Sixth Assessment Report (AR6, 2021-2022), IEA Emission Factors (2024), Poore & Nemecek (2018) Science, Ember Climate Electricity Data, Berners-Lee "How Bad Are Bananas?" (2020).