Carbon footprint calculator: your household CO₂e per year

How this carbon footprint calculator works

A personal carbon footprint is the sum of many small activities, each multiplied by an emission factor. The hard part is not the arithmetic but using factors that match where and how you live. This calculator therefore uses the latest average carbon intensity of your own country’s electricity grid (from Ember via Our World in Data), fuel-specific factors for home heating that include upstream extraction and transport, well-to-wheel factors for cars, distance-band factors for flights that include non-CO₂ warming, and peer-reviewed diet data.

The result is expressed in tonnes of CO₂-equivalent per person per year (CO₂e includes methane and nitrous oxide, weighted by their 100-year warming potential). Home electricity and heating are entered for the whole household and divided by the number of people living there; travel, diet and shopping are entered for you.

Every category then feeds a ranked list of actions. Each action is re-calculated with your inputs (a heat pump’s emissions, for example, are computed on your grid with your heat demand), so the ranking is personal, not generic advice.

The formula

Key factors: natural gas 0.203 kg CO₂e per kWh (gross calorific value, as billed, including upstream); petrol 2.69 and diesel 3.13 kg CO₂e per litre well-to-wheel; short-haul economy flights ≈ 0.15 kg and long-haul economy ≈ 0.15 kg per passenger-km including a radiative-forcing multiplier of 1.7 (business class roughly three times higher on long-haul).

Worked example: a two-person flat in Romania

Take the defaults: two people, 2,500 kWh of electricity and 9,000 kWh of gas a year, a petrol car driven 10,000 km at 6.5 L/100 km, 30 km of public transport a week, one short-haul return flight, a medium-meat diet and average shopping. The result is about 8.0 t CO₂e per person (16 t for the household):

• Electricity: 2,500 kWh × 251 g/kWh ÷ 2 = 0.31 t
• Gas heating: 9,000 kWh × 0.203 kg ÷ 2 = 0.91 t
• Car: 10,000 km × 6.5 L/100 km × 2.69 kg/L = 1.75 t
• Flights: 2 × 1,100 km × 1.08 × 0.151 kg = 0.36 t
• Food 2.05 t, shopping and services 1.7 t, public services 0.8 t, public transport 0.1 t

The top three actions would cut about 2.7 t, a third of the footprint: switching the car to an EV on the Romanian grid (−1.3 t), buying less new stuff (−0.8 t) and going vegetarian (−0.7 t).

How to read the results

• Your footprint is per person. Compare it with the world average of ≈6.6 t CO₂e (all greenhouse gases, EDGAR) and with the 1.5 °C-compatible target of 2.5 t in 2030.
• National fossil CO₂ per person is shown for context. It is territorial (emissions inside the country, excluding imports and methane), so for rich importers the real consumption footprint is higher.
• The doughnut shows which categories dominate; the action chart shows how many tonnes each change would save for you.

Typical values

Tips to cut your footprint

1. Tackle the big three first: car, heating and flights usually make up more than half of a high footprint. One avoided long-haul return flight saves more than a year of careful recycling.
2. Electrify on a clean grid. In countries with grids below ≈400 g/kWh, a heat pump beats a gas boiler and an EV beats a petrol car from the first year.
3. Generate your own power. A rooftop solar system can cover most of a household’s electricity on an annual basis.
4. Eat less beef and cheese. Ruminant products dominate diet emissions; halving them gets most of the benefit of a vegetarian diet.
5. Buy less, keep things longer. Most of a phone’s or laptop’s lifetime footprint is in manufacturing.

Limitations

The calculator uses averages for diet, shopping and public services, which hide large individual differences. Grid factors are annual averages; the marginal emissions of an extra kWh, especially at winter evening peaks, can be higher. Flight emissions vary with aircraft type, seat density and routing, and the size of non-CO₂ effects is still scientifically uncertain (the radiative-forcing multiplier is a convention). Biogenic CO₂ from wood and pellets is excluded, following GHG Protocol practice; this assumes the biomass is harvested sustainably.

Method & assumptions

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