Carbon Footprint Calculator,
estimate your CO2 emissions.

Field guide

How to calculate your personal carbon footprint.

A carbon footprint is the total volume of greenhouse gases an individual generates through their choices and consumption, expressed in metric tons of CO2 equivalent (CO2e) per year. The global average is around 4 metric tons per person per year, but wealthy, high-consumption nations like the United States average closer to 16 metric tons. The scientific consensus suggests that reaching net-zero emissions by 2050 requires each person on Earth to reach roughly 2 metric tons per year.

This calculator covers the three categories that make up the majority of most individuals' footprints: home energy, transportation, and diet. Together, these three areas typically account for 70 to 80 percent of personal emissions.

Home energy

Electricity is generated in ways that vary enormously in carbon intensity. In the United States, the average grid emits approximately 0.4 kilograms of CO2 per kilowatt-hour (kWh), a weighted average across coal, natural gas, nuclear, and renewables. Countries with higher renewable penetration (like Norway or Iceland) have grid factors close to zero, while coal-heavy grids can exceed 0.8 kg/kWh.

Natural gas heating emits approximately 5.3 kg of CO2 per therm burned. Heating oil emits around 10.16 kg per gallon. Both are significantly higher-carbon than heat pumps powered by renewable electricity, which is why electrification of home heating is a major lever in national decarbonisation strategies.

Transportation

Driving a typical gasoline car emits around 0.35 kg of CO2 per mile, based on the US average fuel economy of approximately 28 miles per gallon. Diesel vehicles emit slightly more at 0.40 kg/mile but often achieve better fuel economy. Hybrid vehicles, which recapture braking energy, emit roughly 0.18 kg/mile. Battery electric vehicles charged on the average US grid emit around 0.10 kg/mile, less than a third of a comparable gasoline car, and this number falls further as the grid becomes cleaner.

Aviation is a high-intensity source of emissions. A short-haul flight (under 3 hours) contributes approximately 150 kg of CO2 per passenger. A long-haul flight (over 3 hours) contributes around 1,000 kg (1 metric ton) per passenger. These figures use a radiative forcing multiplier to account for the additional warming effect of water vapor and contrails at altitude, which roughly doubles the warming impact compared to CO2 alone at ground level.

Diet and food

Food production is responsible for roughly 26 percent of global greenhouse gas emissions. Of this, animal agriculture accounts for the majority, with ruminant livestock (cattle and sheep) being especially carbon-intensive due to methane produced in their digestive systems. A diet heavy in beef and lamb can generate 3,000 or more kg of CO2e per year from food alone, while a vegan diet typically falls below 1,500 kg/year.

The emission factors used in this calculator are conservative estimates: heavy meat eater: 3,000 kg/year; medium meat eater: 2,500 kg/year; vegetarian: 1,700 kg/year; vegan: 1,500 kg/year. Actual figures depend on the specific foods consumed, food waste rates, and whether food is locally sourced or transported long distances.

What this calculator does not cover

This tool focuses on the three categories that are both measurable and within most individuals' direct control. It does not capture embedded carbon in manufactured goods (clothing, electronics, appliances), services, government and public expenditure, or waste and wastewater. These indirect emissions, sometimes called Scope 3, can add another 2 to 4 metric tons for a typical consumer in a wealthy nation. Full lifecycle carbon accounting is significantly more complex.

How to reduce your footprint

Research consistently shows that the highest-impact individual actions are, in rough order of magnitude:

• Have one fewer child (if this is a life choice you are considering) is the highest-impact action cited in academic literature, though it is not applicable to most people and represents a deeply personal decision.
• Live car-free or switch to an electric vehicle. If you drive 12,000 miles per year in a gas car, switching to an EV saves roughly 3 metric tons annually. Going car-free saves the whole amount.
• Avoid long-haul flights. One transatlantic round trip contributes around 1.5 to 3 metric tons, more than some people's entire annual budget.
• Switch to a plant-based diet. Moving from a heavy-meat diet to vegan saves around 1.5 metric tons per year.
• Electrify your home heating. Replacing a gas furnace with a heat pump, especially on a renewable tariff, eliminates several hundred kg of annual heating emissions.

Disclaimer

The emission factors used in this calculator are approximations based on US-average data and published scientific literature. Actual emissions vary significantly by location, vehicle model, grid mix, and individual behaviour. This tool is intended for educational awareness, not precise carbon accounting.