How do I calculate my carbon footprint?

Carbon footprint = sum of (activity × emission factor) for each source. Key sources: driving (km × kg CO2/km by fuel type), flights (km × kg CO2/passenger-km × cabin class), electricity (kWh × grid emission factor), and natural gas (m³ × 2.04 kg CO2/m³). Results are in kg CO2-equivalent (CO2e).

How much CO2 does a car produce per km?

Approximate emission factors: petrol/gasoline ≈ 0.19 kg CO2e/km, diesel ≈ 0.17 kg CO2e/km, hybrid ≈ 0.11 kg CO2e/km, electric (US avg grid) ≈ 0.05 kg CO2e/km. Per mile: petrol ≈ 0.31 kg/mile, diesel ≈ 0.27, EV ≈ 0.09. The actual value depends on fuel efficiency and local grid.

How much CO2 does a flight produce?

A rough guide: short-haul flight (under 3 hours) ≈ 0.255 kg CO2e/passenger-km; medium-haul ≈ 0.195 kg CO2e/passenger-km; long-haul ≈ 0.195 kg CO2e/passenger-km. Business class emits ~2–3× more than economy per seat. A London–New York economy round trip emits ~1.6 tonnes CO2e per passenger.

How many trees offset 1 tonne of CO2?

One mature tree absorbs approximately 21 kg of CO2 per year (US Forest Service). To offset 1 tonne (1,000 kg) of CO2 per year, you need about 48 trees. Note that trees take years to grow to full absorption capacity, so tree-planting offsets are a long-term strategy.

Carbon Emission Calculator

Understanding your carbon footprint is the first step to reducing it. This Carbon Emission Calculator covers three of the biggest personal emissions sources: Transport (driving by distance and fuel type, or by fuel consumption), Flights (short, medium, and long-haul with cabin class multipliers), and Home Energy (electricity and natural gas). All emission factors are based on published EPA and IPCC data. Results are shown in kg CO2e (CO2-equivalent, which accounts for all greenhouse gases), with a tree-offset estimate to put the numbers in perspective. Add multiple categories to build up a full personal carbon budget.

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calendar_today Updated: April 2026

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Driving Distance

Distance

Unit

Fuel / Vehicle Type

Period

co2

Enter activity data to calculate emissions

co2 Emission Factors

Car (kg CO₂e/km)

Petrol / Gasoline 0.192

Diesel 0.171

Hybrid 0.110

Electric (US avg) 0.053

Flight (kg CO₂e/pax-km)

Short-haul (<1,500 km) 0.255

Medium-haul 0.195

Long-haul (>4,000 km) 0.147

Home Energy

Electricity (US avg) 0.386 kg/kWh

Natural gas 2.04 kg/m³

forest Global Benchmarks

US avg per person/yr 16,000 kg

Global avg per person/yr 4,700 kg

Paris target per person/yr 2,300 kg

1 tree absorbs/yr 21 kg CO₂

lightbulb Reduce Your Footprint

•Switch to EV: cuts driving emissions ~70% on US avg grid
•Fly economy: business class emits ~2.9× more per seat
•Choose non-stop: layovers add takeoff/landing emissions
•Home heating is often the #1 household emissions source

How to Use This Calculator

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Choose Emission Source

Select Transport (car/driving), Flight, or Home Energy. You can calculate each category separately or combine them for a total footprint.

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Enter Activity Data

For driving: enter distance and fuel type. For flights: enter distance or route and cabin class. For home: enter monthly kWh and/or gas usage.

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Review Your CO2e

See your emissions in kg CO2-equivalent with a breakdown by source and a tree-offset equivalent.

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Compare & Reduce

See how your footprint compares to national and global averages. Use the tips to identify the highest-impact actions.

The Formula

Each activity is multiplied by its corresponding emission factor (kg CO2 per unit of activity). Cabin class multipliers account for the larger seat footprint in business/first class. The radiative forcing index (RFI) of ~1.9 is already included in flight emission factors to account for non-CO2 warming effects at altitude.

CO2e (kg) = Activity × Emission Factor | Car: (Distance × EF_car) | Flight: (Distance × EF_flight × Class multiplier × 2 for return) | Electricity: (kWh × EF_grid) | Gas: (m³ or therm × EF_gas)

lightbulb Variables Explained

EF_car Car emission factor: petrol ≈ 0.192 kg CO2e/km, diesel ≈ 0.171, EV ≈ 0.053 (US grid avg)
EF_flight Flight emission factor: short-haul ≈ 0.255 kg CO2e/km, medium ≈ 0.195, long-haul ≈ 0.195 (per passenger km)
EF_grid Electricity grid emission factor: US avg ≈ 0.386 kg CO2e/kWh (EPA 2023)
EF_gas Natural gas: ≈ 2.04 kg CO2e/m³ or ≈ 5.31 kg CO2e/therm
CO2e CO2-equivalent: accounts for CO2, methane, nitrous oxide and other GHGs
Trees One mature tree absorbs ~21 kg CO2 per year (US Forest Service estimate)

tips_and_updates Pro Tips

The average American emits about 16 tonnes (16,000 kg) of CO2 per year — the global average is ~4.7 tonnes.

Long-haul flights are one of the highest-emission single activities: a round-trip NY–London economy class emits ~1.6 tonnes CO2e.

Switching from a petrol car to an EV cuts driving emissions by ~70% on the US average grid — more on renewable energy.

Home heating (natural gas) is often the single biggest household emissions source in cold climates.

One mature tree absorbs about 21 kg CO2 per year — it takes 50+ trees to offset the average American's annual footprint.

Frequently Asked Questions

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