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Transport Emissions

Green Travel Emissions Comparison

Compare CO2 emissions for the same journey across car, flight, train, bus and bike, and see exactly how much switching modes saves per trip and per year.

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Green Travel Emissions Comparison
Compare CO₂ emissions for the same journey by different transport modes
Annual CO₂ Saving
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Current Mode (per trip)—
Green Alternative (per trip)—
Saving per Trip—
Annual Trips—
Annual CO₂ Saving—
Trees Equivalent—

Disclaimer. Per-km emission factors are planning-level averages by transport mode; actual emissions vary by vehicle occupancy, engine efficiency, route, and the specific carrier or grid electricity mix. Read full disclaimer →

About the Green Travel Emissions Comparison

This calculator compares your current mode of transport against a greener alternative for the exact same journey, using per-passenger-kilometre CO₂ emission factors for each mode. Emissions per trip are calculated as Distance × Emission Factor × 2 (return trip) ÷ Number of Passengers, so carpooling and full trains/buses show a lower per-person footprint than the same vehicle carrying just one or two people.

Emission Factors Used (grams CO₂ per passenger-km)

Petrol Car (solo) — 170 g/km, Car (carpooled, 3 people) — 57 g/km, Short-haul Flight — 255 g/km, Long-haul Flight — 195 g/km (long-haul is lower per-km than short-haul because a flight's highest-emission phase, takeoff and climb, is spread across more distance), Diesel Train — 41 g/km, Coach/Bus — 27 g/km, Electric Train — 14 g/km, Electric Car — 50 g/km (reflecting grid electricity emissions), and Cycling — 0 g/km direct emissions.

Annual CO₂ saved multiplies your per-trip saving by the number of return trips you take per year, and is also converted into an equivalent number of trees planted (using the standard 22 kg CO₂ per tree per year absorption rate applied across this site's environmental calculators).

Frequently Asked Questions

This calculator uses 255 g CO2/km for short-haul flights versus 195 g CO2/km for long-haul, because the most fuel-intensive phase of any flight is takeoff and climb to cruising altitude. On a short flight, that high-emission phase makes up a much larger share of the total distance flown, pulling the average g/km figure up compared to a long-haul flight where more of the journey is efficient cruising.
The calculator rates a carpooled car (3 people) at 57 g CO2 per passenger-km versus 170 g/km for a solo driver -- roughly a two-thirds reduction per person, since the same vehicle's total emissions are simply divided across more passengers. This makes carpooling one of the most accessible ways to cut travel emissions without changing your mode of transport at all.
The electric car is rated at 50 g CO2/km rather than zero because charging it still draws from the electricity grid, which in most regions includes some fossil fuel generation. This is lower than a petrol car's 170 g/km but higher than an electric train's 14 g/km, since trains benefit from much higher passenger capacity spreading the same grid electricity emissions across many more people per trip.
Your total annual CO2 savings in kilograms is divided by 22 kg CO2 per tree per year, the same average absorption rate used across this site's other environmental calculators (Carbon Footprint, Recycling Impact, Tree Planting), to give a rough sense of how many mature trees' worth of yearly absorption your travel mode switch represents.
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Related: EV vs Petrol Cost Comparison, Carbon Footprint Calculator, All Environmental Tools