Carbon Footprint of a 100 km Trip - Car vs Train vs Plane

Every kilometer generates a CO2 number - and every transport mode has a different one

A bicycle produces 0 grams of CO2 per kilometer. A bus adds 27 g. A train emits 41 g. A gasoline car at default consumption releases 173 g. A short-haul flight tops the chart at 255 g/km per passenger. These numbers determine your travel carbon footprint - and most travelers never see them side by side. This calculator places every transport mode on the same route, ranks them from cleanest to dirtiest and converts the total into kilograms, tree equivalents and flight equivalents so you can make an informed choice before every trip.

Key numbers at a glance

0 g/km

Bicycle

Zero direct emissions

27 g/km

Bus

Lowest motorized mode

41 g/km

Train

Electric rail average

173 g/km

Car - gasoline

At 7.5 l/100 km, 1 person

195 g/km

Plane - long-haul

Over 1,500 km routes

255 g/km

Plane - short-haul

Under 1,500 km routes

Atlas of transport emissions - detailed profiles

Each transport category has its own emission profile, efficiency range and context. Below is an encyclopedia-style breakdown of every mode this calculator covers.

Bicycle - 0 g CO2/km

Zero direct emissions. The only carbon cost is the manufacturing of the bicycle itself (roughly 5 kg CO2 for a basic bike, amortized over thousands of kilometers). Practical for distances up to 15-20 km in urban areas. An e-bike adds about 3-5 g/km from electricity consumption but remains far below any motorized transport. Average speed: 15-25 km/h in cities.

Range: 0 g/km (pedal) to 5 g/km (e-bike) | Best for: urban commutes under 20 km | Limitation: weather, distance, cargo capacity

Bus - 27 g CO2/km per passenger

The lowest-emission motorized transport per passenger-kilometer. A full intercity bus carrying 40-50 passengers produces roughly 1,000-1,300 g/km total, but divided among passengers that drops to just 27 g/km. Modern coaches achieve 20-25 l diesel/100 km. Electric city buses are even cleaner. The figure varies by occupancy - a half-empty bus may emit 40-50 g/km per passenger.

Range: 20-50 g/km depending on occupancy | Best for: intercity travel 100-800 km | Example: NYC to Boston by bus = 9.5 kg CO2 (350 km)

Train - 41 g CO2/km per passenger

Electric trains are highly efficient per passenger-kilometer. The 41 g/km average includes a mix of electric and diesel rail. In countries with clean electricity grids (France, Sweden), electric trains emit as low as 5-10 g/km. Diesel regional trains can reach 60-80 g/km. High-speed trains (TGV, ICE, Shinkansen) typically fall in the 20-40 g/km range due to high occupancy. A London to Edinburgh trip by train (650 km) produces about 27 kg CO2.

Range: 5-80 g/km depending on grid and train type | Best for: 200-1,500 km intercity | Example: Paris to Berlin by train = 43 kg CO2 (1,050 km)

Car - 68 to 173 g CO2/km (varies by fuel and passengers)

Car emissions depend heavily on fuel type, consumption and number of passengers. Default emissions per km (solo driver): gasoline at 7.5 l/100 km = 173 g, diesel at 6.0 l/100 km = 161 g, LPG at 9.5 l/100 km = 143 g, hybrid at 4.5 l/100 km = 104 g, EV at 17 kWh/100 km = 68 g (US/EU grid). Carpooling cuts per-person emissions proportionally: 4 passengers in a gasoline car bring it down to 43 g/km per person - below a train. Custom fuel consumption overrides the default.

Range: 0-250+ g/km depending on fuel, consumption and occupancy | Best for: flexible door-to-door travel | Carpooling makes it competitive with trains

Plane - 195 to 255 g CO2/km per passenger

Aviation is the most carbon-intensive common transport mode per passenger-kilometer. Short-haul flights (under 1,500 km) emit 255 g/km because takeoff and climb burn disproportionate fuel relative to the short cruise distance. Long-haul flights (over 1,500 km) are more efficient at 195 g/km since cruise phase dominates. A round-trip New York to London flight (about 5,600 km each way) produces roughly 500 kg CO2 per passenger. These figures do not include radiative forcing (non-CO2 climate effects at altitude), which approximately doubles the climate impact.

Range: 195-255 g/km depending on distance | Best for: distances over 1,500 km where time matters | Note: radiative forcing not included in base figure

Classification ranking - transport modes from cleanest to dirtiest

Rank	Transport mode	g CO2/km	Class	500 km trip (kg)
1	Bicycle	0	Zero	0
2	Bus	27	Very low	13.5
3	Train	41	Low	20.5
4	Car - EV (1 person)	68	Low	34.0
5	Car - hybrid (1 person)	104	Medium	52.0
6	Car - LPG (1 person)	143	Medium	71.7
7	Car - diesel (1 person)	161	High	80.4
8	Car - gasoline (1 person)	173	High	86.6
9	Plane - long-haul	195	Very high	97.5
10	Plane - short-haul	255	Highest	127.5

How to use this calculator - step by step

Distance (km) - enter the one-way distance of your trip in kilometers. Use great-circle distance for flights, driving distance for cars. Examples: NYC to Boston 350 km, London to Edinburgh 650 km, Paris to Berlin 1,050 km. Maximum 20,000 km.
Round trip - select "Round trip (x2)" to automatically double the distance. Most travel footprint comparisons use round-trip numbers since you typically return to your starting point.
Transport mode - pick from 10 options: five car fuel types (gasoline, diesel, LPG, hybrid, EV), train, bus, short-haul plane (under 1,500 km), long-haul plane (over 1,500 km) or bicycle. The option values stay the same internally but labels are in English.
Passengers in car - this field appears only when you select a car type. Choose 1-5. The total car emission is divided by the number of passengers to give per-person figures. With 4 passengers, a gasoline car drops from 173 g/km to 43 g/km per person.
Fuel consumption (l/100 km) - optional field, visible only for gasoline, diesel, LPG and hybrid cars. Enter your actual consumption to override the default. Defaults: gasoline 7.5, diesel 6.0, LPG 9.5, hybrid 4.5 l/100 km. Range: 2-30 l/100 km.
Read the results - the calculator shows your total CO2 in kg, emission per km in grams, tree equivalents (22 kg CO2/tree/year), flight equivalents (500 kg CO2 per New York-London round trip) and a full comparison table ranking all transport modes on the same route.

Practical examples - real routes compared

Route	Transport	Distance	CO2 (kg)	Trees needed
NYC to Boston (round trip)	Car - gasoline (1 person)	700 km	121.3	5.5
NYC to Boston (round trip)	Train	700 km	28.7	1.3
London to Edinburgh (one way)	Plane - short-haul	650 km	165.8	7.5
London to Edinburgh (one way)	Train	650 km	26.7	1.2
Paris to Berlin (round trip)	Car - diesel (1 person)	2,100 km	337.7	15.3
Paris to Berlin (round trip)	Bus	2,100 km	56.7	2.6
New York to London (round trip)	Plane - long-haul	11,200 km	2,184.0	99.3
Daily commute 30 km (round trip, 250 days)	Car - gasoline (1 person)	15,000 km	2,598.8	118.1
Daily commute 30 km (round trip, 250 days)	Car - gasoline (3 people)	15,000 km	866.3	39.4
Daily commute 30 km (round trip, 250 days)	Car - EV (1 person)	15,000 km	1,020.0	46.4

How the calculation works

Total distance: If round trip is selected, the entered distance is multiplied by 2. Example: 500 km one way becomes 1,000 km round trip.
Public transport and planes: CO2 (kg) = total distance (km) x emission factor (g/km) / 1000. For a 500 km train trip: 500 x 41 / 1000 = 20.5 kg CO2.
Car (combustion): CO2 (kg) = (total distance / 100) x fuel consumption (l/100 km) x CO2 factor (kg/l). For 500 km gasoline at 7.5 l/100 km: (500/100) x 7.5 x 2.31 = 86.6 kg CO2.
Car (EV): CO2 (kg) = (total distance / 100) x electricity consumption (kWh/100 km) x grid factor (kg/kWh). For 500 km at 17 kWh/100 km: (500/100) x 17 x 0.400 = 34.0 kg CO2. The grid factor is 400 g CO2/kWh (US/EU average).
Per-person (car): Total car CO2 is divided by the number of passengers. 86.6 kg / 3 people = 28.9 kg/person.
CO2 factors: Gasoline 2.31 kg/l, diesel 2.68 kg/l, LPG 1.51 kg/l (IPCC). Hybrid uses the gasoline factor at lower consumption.
Default consumption: Gasoline 7.5, diesel 6.0, LPG 9.5, hybrid 4.5 l/100 km, EV 17 kWh/100 km.
Tree equivalent: Total CO2 / 22 (one mature tree absorbs about 22 kg CO2 per year).
Flight equivalent: Total CO2 / 500 (one round-trip New York to London flight produces about 500 kg CO2 per passenger).
Comparison table: All 10 transport modes are calculated for the same route and sorted from lowest to highest emission, so you can instantly see which option produces the least CO2.

FAQ - Frequently asked questions

Why does a short-haul flight emit more per km than a long-haul flight?

Takeoff and climb are the most fuel-intensive phases of a flight. On a short route (under 1,500 km), these phases account for a much larger share of total flight time. A plane burns roughly 30-40% of its fuel during takeoff, climb and landing regardless of route length. On a 500 km flight, this fixed fuel cost is spread over a short distance, resulting in 255 g CO2/km. On a 5,000 km flight, the long cruise phase (which is very fuel-efficient) brings the average down to 195 g/km. This is why trains are often recommended for routes under 800-1,000 km where they are competitive on total travel time.

How does carpooling change the emissions comparison?

Carpooling divides the total car emission by the number of passengers. A gasoline car at 7.5 l/100 km emits 173 g/km in total. With 2 people that is 87 g/km per person - comparable to a hybrid. With 3 people it drops to 58 g/km - below a train (41 g/km is per-passenger already, but the car figure per person at 3-4 occupants beats many rail scenarios). With 4 people it falls to 43 g/km per person. This makes a full gasoline car competitive with a train and far better than a plane. The bus (27 g/km) remains the most efficient motorized option, but carpooling closes the gap significantly.

What does the 400 g CO2/kWh grid mix mean for EVs?

The 400 g CO2/kWh figure is an approximate average for the US and EU electricity grid. It means that producing 1 kWh of electricity releases 400 grams of CO2 from the power plants in the mix (coal, gas, nuclear, renewables combined). For an EV using 17 kWh/100 km, this translates to 68 g CO2/km. However, this varies dramatically by country: Norway (mostly hydropower) is around 20 g/kWh, France (nuclear) about 60 g/kWh, Germany about 350 g/kWh, Poland about 670 g/kWh, and some US states using coal can exceed 700 g/kWh. If you charge from home solar panels, the grid factor is effectively 0 g/kWh and EV emissions drop to near zero.

Should I use driving distance or straight-line distance for flights?

For flights, use great-circle distance (the shortest path between two airports on the globe), not driving distance. For example, New York to London is about 5,570 km by air but there is no driving route. London to Edinburgh is about 530 km by air versus 650 km by road. For comparing a flight against a train or car on the same route, you can use the driving/rail distance for ground transport and the air distance for the flight. Online tools like Great Circle Mapper give accurate air distances. This calculator uses a single distance for all modes, so for a fair comparison enter the road distance and accept that the flight distance would be slightly shorter.

How accurate are the 22 kg CO2/tree and 500 kg CO2/flight figures?

The 22 kg CO2/tree/year is a widely cited average for a mature deciduous tree in a temperate climate. Actual absorption varies from 10 kg (small young tree) to 50 kg (large old-growth tree) per year, depending on species, age, health and climate. Tropical trees absorb more due to year-round growth. The 500 kg CO2 for a New York-London round trip is a rough per-passenger estimate based on total fuel burn divided by seat count at typical load factors. Business class passengers get roughly 2-3x more allocated emissions due to larger seat area. These are order-of-magnitude reference points, not precise values.

Why is the bus figure (27 g/km) lower than the train (41 g/km)?

This may seem counterintuitive since trains are often considered greener. The 27 g/km for buses reflects modern intercity coaches operating at high occupancy (40-50 passengers). They are diesel-powered but extremely fuel-efficient per passenger at full capacity. The 41 g/km train figure is an international average that includes both electric trains (very clean) and diesel regional services (higher emissions), as well as varying occupancy rates. In countries with clean grids and high-speed electric rail (France, Japan), trains can emit as little as 5-15 g/km per passenger, well below buses. The averages used here represent a global/international benchmark.

Related tools

Road Trip Calculator

Calculate total driving time with rest breaks, fuel stops and meals for any distance - Open calculator

Car CO2 Emissions Calculator

Calculate your car CO2 emissions in g/km and kg/year from fuel consumption with EU norm comparison - Open calculator

Fuel Consumption Calculator

Convert fuel consumption between l/100 km, MPG and km/l for any vehicle type - Open calculator

EV vs ICE Calculator

Compare total cost and emissions of an electric vehicle versus a combustion engine car over multiple years - Open calculator

Carpooling Cost Calculator

Split fuel costs among passengers and calculate savings per person for any trip - Open calculator

Commute Cost Calculator

Calculate the true monthly and annual cost of your daily commute by car - Open calculator

100 km trip - CO2 emissions by car, train, bus and plane

Parameters