Worked example
This is the example in the answer above: one person in a two-person UK home. The household uses 250 kWh of electricity and 1,000 kWh of gas a month. The person drives 8,000 km a year in a petrol car, travels 500 km by bus and 1,000 km by train, takes one short-haul return flight, eats a medium amount of meat and spends £155 a month across the five shopping categories. It is an illustration, not a typical household.
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| Input | Answer | Factor | Per year (kg CO₂e) |
|---|---|---|---|
| Electricity | 250 kWh/month ÷ 2 people | 0.14395 kg/kWh (DESNZ, incl. T&D) | 216 |
| Natural gas | 1,000 kWh/month ÷ 2 people | 0.18231 kg/kWh (DESNZ) | 1,094 |
| Car, petrol | 8,000 km/year | 0.16152 kg/km (DESNZ) | 1,292 |
| Bus | 500 km/year | 0.10151 kg/km (DESNZ) | 51 |
| Train | 1,000 km/year | 0.03092 kg/km (DESNZ) | 31 |
| Short-haul flight | 1 return (2 × 1,484 km) | 0.12786 kg/pkm, with RF (DESNZ) | 379 |
| Food | Medium meat-eater, 365 days | 7.04 kg/day (Scarborough et al.) | 2,570 |
| Shopping | £155/month across 5 categories | kg per £, by category (Defra) | 1,112 |
As of Oct 2026
Total: 6,744 kg = 6.7 t CO₂e a year (home 1.3 t, travel 1.8 t, food 2.6 t, shopping 1.1 t). For comparison, UK fossil CO₂ emissions were 4.5 t per person in 2024, a narrower measure that leaves out other greenhouse gases and imported goods.
How we calculate
Each answer is multiplied by a published emission factor, and the results are added up:
- Home. Electricity and heating fuel are multiplied by DESNZ factorsSource 1 and divided by the number of people in your home. For electricity outside the UK, we use your country’s grid intensity from Ember via Our World in DataSource 6. Where a country has no figure, we use the world average.
- Travel. Car, bus, coach and train kilometres use DESNZ factorsSource 1. Flights use DESNZ’s average one-way distance for each type of flightSource 2 and its average-passenger factor including non-CO₂ effectsSource 1.
- Food. Your diet group sets a daily figure from a study of 55,504 UK adults, which we multiply by 365Source 3.
- Shopping. Monthly spending in pounds is multiplied by Defra’s spend-based multipliers for 2023, which estimate the full supply-chain emissions per pound spentSource 4.
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| Input | Factor | Unit | Source |
|---|---|---|---|
| Electricity (UK grid, generation) | 0.13096 | kg CO₂e per kWh | Department for Energy Security and Net Zero, 2026 |
| Electricity transmission and distribution losses (UK) | 0.01299 | kg CO₂e per kWh | Department for Energy Security and Net Zero, 2026 |
| Natural gas | 0.18231 | kg CO₂e per kWh (gross CV) | Department for Energy Security and Net Zero, 2026 |
| Heating oil (burning oil / kerosene) | 2.54016 | kg CO₂e per litre | Department for Energy Security and Net Zero, 2026 |
| LPG | 1.55713 | kg CO₂e per litre | Department for Energy Security and Net Zero, 2026 |
As of Oct 2026
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| Input | Factor | Unit | Source |
|---|---|---|---|
| Car, average size, petrol | 0.16152 | kg CO₂e per vehicle-km | Department for Energy Security and Net Zero, 2026 |
| Car, average size, diesel | 0.17265 | kg CO₂e per vehicle-km | Department for Energy Security and Net Zero, 2026 |
| Car, average size, hybrid | 0.12961 | kg CO₂e per vehicle-km | Department for Energy Security and Net Zero, 2026 |
| Car, average size, plug-in hybrid (fuel part) | 0.08959 | kg CO₂e per vehicle-km | Department for Energy Security and Net Zero, 2026 |
| Car, average size, plug-in hybrid (electricity part, UK grid) | 0.00873 | kg CO₂e per vehicle-km | Department for Energy Security and Net Zero, 2026 |
| Car, average size, battery electric (UK grid electricity) | 0.02686 | kg CO₂e per vehicle-km | Department for Energy Security and Net Zero, 2026 |
| Car, average size, battery electric (UK grid T&D losses) | 0.00266 | kg CO₂e per vehicle-km | Department for Energy Security and Net Zero, 2026 |
| Car, average size, fuel unknown | 0.16591 | kg CO₂e per vehicle-km | Department for Energy Security and Net Zero, 2026 |
| Bus, average local bus | 0.10151 | kg CO₂e per passenger-km | Department for Energy Security and Net Zero, 2026 |
| Coach | 0.03948 | kg CO₂e per passenger-km | Department for Energy Security and Net Zero, 2026 |
| National rail | 0.03092 | kg CO₂e per passenger-km | Department for Energy Security and Net Zero, 2026 |
| Flight, domestic (average passenger, with RF; 434 km average one-way distance) | 0.22928 | kg CO₂e per passenger-km | DESNZ, 2026 |
| Flight, short-haul (average passenger, with RF; 1,484 km average one-way distance) | 0.12786 | kg CO₂e per passenger-km | DESNZ, 2026 |
| Flight, long-haul (average passenger, with RF; 6,799 km average one-way distance) | 0.15282 | kg CO₂e per passenger-km | DESNZ, 2026 |
As of Oct 2026
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| Input | Factor | Unit | Source |
|---|---|---|---|
| Vegan | 2.47 | kg CO₂e per person per day | Scarborough, Clark, Cobiac et al., Nature Food, 2023 |
| Vegetarian | 4.16 | kg CO₂e per person per day | Scarborough, Clark, Cobiac et al., Nature Food, 2023 |
| Fish-eater (pescatarian) | 4.74 | kg CO₂e per person per day | Scarborough, Clark, Cobiac et al., Nature Food, 2023 |
| Low meat-eater (under 50 g meat a day) | 5.37 | kg CO₂e per person per day | Scarborough, Clark, Cobiac et al., Nature Food, 2023 |
| Medium meat-eater (50–99 g meat a day) | 7.04 | kg CO₂e per person per day | Scarborough, Clark, Cobiac et al., Nature Food, 2023 |
| High meat-eater (100 g or more meat a day) | 10.24 | kg CO₂e per person per day | Scarborough, Clark, Cobiac et al., Nature Food, 2023 |
As of Oct 2026
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| Input | Factor | Unit | Source |
|---|---|---|---|
| Clothing (garments) | 0.3535 | kg CO₂e per £ spent (2023 prices, incl. VAT) | Department for Environment, Food & Rural Affairs, 2023 |
| Shoes and other footwear | 0.343 | kg CO₂e per £ spent (2023 prices, incl. VAT) | Department for Environment, Food & Rural Affairs, 2023 |
| Computers and IT equipment | 1.5427 | kg CO₂e per £ spent (2023 prices, incl. VAT) | Department for Environment, Food & Rural Affairs, 2023 |
| Furniture and furnishings | 0.3805 | kg CO₂e per £ spent (2023 prices, incl. VAT) | Department for Environment, Food & Rural Affairs, 2023 |
| Restaurants and cafes | 0.6797 | kg CO₂e per £ spent (2023 prices, incl. VAT) | Department for Environment, Food & Rural Affairs, 2023 |
As of Oct 2026
The country comparison uses fossil CO₂ per person from Our World in DataSource 5. It covers emissions produced within the country, and leaves out other greenhouse gases and imported goods, so treat it as a rough reference rather than a like-for-like comparison.
The three suggested actions are calculated from your own answers. For example, the saving from eating less meat is the difference between your diet group and the next one down.
Limitations
An estimate, not an audit
The factors are averages, mostly for the UK. Electric car charging uses the UK grid factor wherever you live, and the shopping multipliers are UK figures in pounds at 2023 prices, so results outside the UK are rougher. The calculator leaves out some sources, such as wood heating, district heat, motorbikes and ferries.
Once you know your biggest sources, cut what you can first. Our guide to buying carbon credits as an individual explains what to check if you then offset the rest, and the flight emissions calculator works out a specific flight. All our calculators are listed on the tools page.