Flying vs Driving: Which Produces Fewer Carbon Emissions?

If you have an electric car, drive.

If two or more people are sharing an average petrol or diesel car, driving will also usually produce lower emissions per person than flying.

If you are travelling alone in a petrol or diesel car, the answer depends on the journey.

Over the same distance, a solo average petrol car produces 207.51g CO₂e per kilometre. The UK Government’s short-haul economy flight figure is 148.25g CO₂e per passenger-kilometre, so on that comparison flying is lower.

A UK domestic flight between two British cities, such as London and Edinburgh, is very different. The Government figure is 262.78g CO₂e per passenger-kilometre, so over the same distance it would be better to drive.

That does not make flying low-carbon. It means only that one person driving a conventional car can sometimes be even worse. A flight still releases a substantial amount of carbon, and for genuinely long-haul journeys such as London to New York or Sydney there is no realistic driving alternative anyway. The lower per-kilometre figure for long-haul flying should not be read as a green light to fly.

The actual route can also change the result. From London to Aberdeen, one person in an average petrol car produces about 179.5kg CO₂e, compared with 170.2kg for flying. The flight is slightly lower because the road journey is much longer. Put two people in the car and the driving figure falls to 89.7kg each, so the shared car is far lower.

For someone deciding how to travel, I would reduce it to four rules:

• Electric car: drive.
• Two or more people in a petrol or diesel car: usually drive.
• One person in a petrol or diesel car: calculate the actual journey.
• A practical train is available: check the train first.

Flying vs driving emissions per passenger-kilometre

These are the UK Government’s 2026 conversion factors, with the same broad emissions boundary applied to each mode.

Travel option	2026 emissions per passenger-km	What that means
UK domestic flight, average passenger	262.78g CO₂e/passenger-km	Higher than a solo average petrol or diesel car over the same distance
UK short-haul economy flight	148.25g CO₂e/passenger-km	Lower than a solo average petrol or diesel car, but higher than the same car shared by two
UK long-haul economy flight	141.65g CO₂e/passenger-km	Lower per kilometre than a solo average petrol or diesel car, although driving is rarely a realistic alternative on a genuinely long-haul route
Average petrol car, 1 person	207.51g CO₂e/passenger-km	Higher than short-haul and long-haul economy flying
Average petrol car, 2 people	103.76g CO₂e/passenger-km	Lower than all three flight categories above
Average petrol car, 4 people	51.88g CO₂e/passenger-km	Far lower than flying
Average diesel car, 1 person	214.11g CO₂e/passenger-km	Higher than short-haul and long-haul economy flying
Average diesel car, 2 people	107.06g CO₂e/passenger-km	Lower than all three flight categories above
Average battery-electric car, 1 person	40.01g CO₂e/passenger-km	Far below flying
National rail, average passenger	39.89g CO₂e/passenger-km	The lowest figure in this table, just below an average electric car carrying one person

The table is easier to understand if you ignore most of the numbers and look at the changes that affect your decision.

A solo petrol car is 207.51g. A short-haul economy flight is 148.25g. If the two journeys were exactly the same distance, the flight would be lower.

Put a second person in the petrol car and its per-person figure falls to 103.76g. Now the car is lower.

A domestic UK flight is 262.78g. Even with one person in the average petrol or diesel car, driving is lower over the same distance.

An electric car is 40.01g with one person. It is much lower than flying.

National rail is 39.89g. If there is a sensible train for the journey, it is usually the lowest-emission choice in this comparison.

We built these figures from the UK Government’s 2026 greenhouse gas conversion factors. For petrol and diesel cars, we added the Government’s well-to-tank factor to the vehicle emissions. For electric cars, we included electricity generation, transmission and distribution losses, and upstream electricity emissions. For flights, we used the Government aviation factors including its central treatment of aviation’s non-CO₂ effects, plus well-to-tank emissions from aviation fuel. The rail figure is the national rail factor plus its own well-to-tank factor, so the train sits on the same boundary as everything else here.

I would not compare a flight figure that includes producing the fuel with a car figure that quietly leaves petrol production out. Both numbers may look official, but they are not answering the same question.

Updated September 2026, using the UK Government’s 2026 greenhouse gas conversion factors. Source: Department for Energy Security and Net Zero, greenhouse gas reporting conversion factors 2026. View the publication. Comparisons built on earlier datasets can differ from these figures by a noticeable margin.

If a train works for the journey, it is normally the first alternative I would check. You can compare train and plane emissions in more detail.

Is driving greener than flying?

Sometimes. The answer changes mainly with three things: the type of flight, how many people are in the car and how much farther the road route is.

Start with a UK domestic flight. The Government average is 262.78g CO₂e per passenger-kilometre.

One person in an average petrol car is 207.51g. One person in an average diesel car is 214.11g.

So if you are deciding between driving and flying between two UK cities and the distances are broadly comparable, the car has the lower emissions even with only one person in it.

Short-haul economy flying changes the picture. The Government figure is 148.25g CO₂e per passenger-kilometre.

That is lower than a solo petrol car at 207.51g and a solo diesel car at 214.11g.

So if one person is comparing an average conventional car with a short-haul economy flight over the same number of kilometres, the flight has the lower figure.

Again, that does not make the flight low-carbon. It tells you that moving a whole petrol or diesel car for one person is also carbon-intensive.

Add a second person to the car and the conclusion changes. A petrol car falls to 103.76g per person and a diesel car to 107.06g.

With two people sharing, the car is lower than domestic, short-haul economy and long-haul economy flying.

Why the number of people in the car matters so much

The Government car figures are published per vehicle-kilometre.

The aviation figures are published per passenger-kilometre.

That difference is easy to miss and it changes the answer.

An average petrol car produces 207.51g CO₂e for each kilometre the vehicle travels. If one person is inside, that whole figure belongs to one traveller.

Put two people in the car and the vehicle does not suddenly produce twice as much. The same 207.51g is shared between two people, giving 103.76g each.

With four people it falls to 51.88g each.

The flight figure already belongs to one passenger. You do not divide it by the number of people on the aircraft.

I have seen comparisons where two emissions figures are put side by side because both are expressed in grams of CO₂e. That is not enough. If one is per vehicle and one is per passenger, the conclusion can be wrong before anyone has even started arguing about which mode is greener.

How many people need to share a car before driving is lower-carbon than flying?

For the average petrol and diesel cars used here, two people are enough.

With two people:

• average petrol car: 103.76g CO₂e per person-km
• average diesel car: 107.06g CO₂e per person-km

Both are lower than:

• UK domestic flight: 262.78g
• short-haul economy flight: 148.25g
• long-haul economy flight: 141.65g

So if two people are making the same journey in an average petrol or diesel car, driving has the lower emissions per person on an equal-distance comparison.

An electric car is already lower with one person at 40.01g.

The only reason I would not make “two people means drive” an absolute rule is that the road route can be considerably longer than the flight route. You need to compare the journey you will actually make.

When can flying produce fewer emissions than driving?

The case to watch is one person driving a petrol or diesel car for a long journey.

On an equal-distance comparison:

• solo petrol car: 207.51g CO₂e/km
• solo diesel car: 214.11g CO₂e/km
• short-haul economy flight: 148.25g CO₂e/passenger-km
• long-haul economy flight: 141.65g CO₂e/passenger-km

So against short-haul or long-haul economy flying, the solo conventional car has the higher per-kilometre figure.

I would not take the long-haul result too literally as a travel choice. Nobody is deciding whether to drive from London to New York or London to Sydney. It is useful because it shows that flying does not necessarily have the highest figure per kilometre, not because driving is a serious substitute for intercontinental travel.

And the absolute emissions still matter. A long-haul flight covers thousands of kilometres, so even a lower figure per kilometre produces a large total footprint. Flying can beat a solo petrol car in a narrow comparison and still be a high-emission way to travel.

Domestic flying is different. At 262.78g per passenger-kilometre, the domestic flight figure is above both the solo petrol and solo diesel car figures.

If you are considering a UK flight between cities such as London and Edinburgh, driving is lower over the same distance.

Real UK journeys show what actually happens

Equal-distance figures help explain the mechanics. They are not the journey you will actually make.

We therefore ran three one-way journeys from London using the 2026 factors. The road distance is the shortest practical driving route from central London using OpenStreetMap routing data. The flight distance is the great-circle distance from Heathrow to the destination airport.

Every emissions figure below is kilograms of CO₂e for one traveller.

Journey, one way	Road	Flight	Domestic flight	Petrol car, 1 person	Petrol car, 2 people	Electric car
London to Edinburgh	655km	534km	140.3kg	135.9kg	68.0kg	26.2kg
London to Glasgow	650km	555km	145.9kg	134.9kg	67.4kg	26.0kg
London to Aberdeen	865km	648km	170.2kg	179.5kg	89.7kg	34.6kg

In miles, the road routes are 407, 404 and 537. The flight routes are 332, 345 and 402.

London to Edinburgh

Flying produces 140.3kg CO₂e.

One person in the average petrol car produces 135.9kg.

Driving is lower, but only by 4.4kg.

With two people in the petrol car, the figure falls to 68.0kg each.

The shared car produces less than half the emissions per person of the flight.

The electric car produces 26.2kg.

It is much lower than either.

London to Glasgow

Flying produces 145.9kg CO₂e.

One person in the average petrol car produces 134.9kg.

Driving is lower by about 11kg.

With two people in the car, the figure falls to 67.4kg each.

The electric car produces 26.0kg.

Again, sharing the car changes the comparison substantially, and the electric car is lower by a wide margin.

London to Aberdeen

This is the journey that changes the pattern.

Flying produces 170.2kg CO₂e.

One person in the average petrol car produces 179.5kg.

Flying is lower by about 9.3kg.

That happens because the road route is much longer: 865km by road against 648km by air.

Put two people in the petrol car and the driving figure falls to 89.7kg each.

The shared car is then far lower than flying.

This is why I would not use a rule such as “under 500 miles, drive” or “driving always beats flying”. London to Aberdeen shows that the route itself can overturn an equal-distance comparison.

Getting to and from the airport is excluded from the flight examples above. Including those journeys would increase the flight figure, so leaving them out is slightly generous to flying.

How road distance changes the answer

A flight calculation normally starts with the great-circle distance between airports. A car follows roads.

Those are not the same thing.

If the flight distance is 800km and the drive is 1,000km, the car emits over 1,000km. You cannot compare both modes over 800km because that is not the journey the car makes.

This sounds obvious until you look at how many simple comparisons use one distance for both modes.

For a real decision, use:

Flight emissions = actual flight calculation for the route

Driving emissions per person = road distance × vehicle emissions per kilometre ÷ number of occupants

The extra road distance can be enough to turn a solo car from the lower-emission option into the higher one.

The UK aviation factor already includes an 8% distance uplift

There is one methodological detail I would check before trusting a flight calculator using the UK Government factors.

Aircraft do not fly a perfect great-circle route. Air traffic routing, holding and other operational effects add distance.

The Government accounts for this with an 8% uplift.

The 2026 methodology says that uplift is already incorporated into the published aviation conversion factors.

So if you calculate the great-circle distance between two airports and then apply the published factor, do not add another 8% to the distance.

You would count the same allowance twice and make the flight look worse than the Government methodology intends.

The relevant explanation is in sections 8.37 and 8.38 of the 2026 methodology.

Source: the 2026 Government conversion factors methodology paper, sections 8.37 to 8.38. View the methodology.

Why aviation’s non-CO₂ effects are included

Aircraft affect the climate through more than the carbon dioxide released by burning jet fuel. Nitrogen oxides, water vapour, contrails and associated cloud effects also contribute.

The UK Government recommends a 1.7 multiplier on the CO₂ component as a central estimate when these non-CO₂ effects are included.

It also says the estimate is uncertain and is not a simple claim that all of those effects are literally equivalent to another fixed quantity of long-lived CO₂.

I think leaving them out altogether would be the bigger mistake. It would make the aviation number look cleaner by ignoring a recognised part of the climate impact.

At the same time, I would not present 1.7 as though the scientific uncertainty has disappeared. It has not.

At C Level we use the Government’s central estimate and make that uncertainty clear. For a practical travel comparison, that is more useful than either treating the effect as zero or pretending it can be measured with false precision.

The Government methodology discusses this in sections 8.39 to 8.44 and draws on work including Lee and others, 2021.

Sources: the 2026 Government conversion factors methodology paper, sections 8.39 to 8.44. View the methodology. Lee and others, 2021, Atmospheric Environment. View the record.

Why different flying-vs-driving comparisons give different answers

The calculation boundary can change the result.

For this article we include:

• direct petrol and diesel vehicle emissions;
• upstream production and distribution of petrol and diesel;
• electricity generation, transmission and distribution losses, and upstream electricity emissions for the electric car;
• direct aviation emissions;
• upstream aviation-fuel emissions;
• the Government’s central treatment of aviation non-CO₂ effects.

We exclude vehicle manufacture, aircraft manufacture and infrastructure.

That matters because the comparison becomes misleading if one mode carries costs the other does not.

If you count producing the jet fuel but leave petrol production out, flying looks worse than it should in a like-for-like comparison.

If you add battery manufacture to the electric car but exclude aircraft manufacture, the electric car is carrying a wider lifecycle boundary than the flight.

If another article gives you very different numbers, I would check what has been counted before assuming somebody has made an arithmetic error.

For business reporting, boundaries matter even more. If travel emissions are being used in a tender or a Carbon Reduction Plan, the reader needs to know what the number includes.

Are electric cars lower-carbon than flying?

Yes. On the journey-emissions boundary used here, the difference is large.

The 2026 Government figures give an average battery-electric car approximately:

• 26.86g CO₂e/km from electricity generation;
• 2.66g CO₂e/km from transmission and distribution losses;
• 10.49g CO₂e/km from upstream electricity emissions.

The total is 40.01g CO₂e per vehicle-kilometre.

Short-haul economy flying is 148.25g.

So with one person in the car, the average electric car produces about 73% less per kilometre than short-haul economy flying on this boundary.

With two people in the electric car, the per-person figure falls to about 20g.

With four people, it is about 10g.

This is a journey-emissions comparison, not a full lifecycle assessment, but the use-phase difference is nowhere near close.

Source: the 2026 conversion factors and their methodology, Department for Energy Security and Net Zero. View the publication.

What about manufacturing the car or aircraft?

Vehicle manufacture is not included in these journey figures.

That means we do not allocate battery manufacture to the electric car, but we also do not allocate the manufacture of the petrol car, diesel car or aircraft to an individual journey.

Road construction and airport construction are outside the boundary too.

Battery manufacture is a legitimate issue if you want a full lifecycle comparison. What I would not do is add it only to the electric-car side and then call the result fair.

If you want to compare whole technologies over their lifetimes, use comparable lifecycle boundaries for all of them.

If you want to decide which mode produces fewer emissions for a particular journey, keep the journey boundary consistent.

Your own car may be very different from the average

The Government’s average-car figure is useful when you know nothing more specific.

If you know how much fuel your own car actually uses, that is better information.

A small petrol hatchback, a large SUV and an old diesel do not use the same amount of fuel. If you have reliable fuel consumption for your car, I would calculate from that rather than assume you own the Government’s average vehicle.

The Government methodology makes much the same distinction. Distance-based passenger transport factors are intended for situations where actual fuel or electricity consumption is not available.

If you do not know the real fuel use, use the average. An honest average is better than a supposedly precise answer built from a guess.

Source: the 2026 Government conversion factors methodology paper. View the methodology.

So should you fly or drive?

If you have an electric car, drive.

If two or more people are sharing a petrol or diesel car, driving will usually produce lower emissions per person than flying.

If you are travelling alone in a petrol or diesel car, do not assume either option wins. A domestic UK flight usually compares badly with the car, but a short-haul economy flight can have the lower per-kilometre figure. The real road distance can change the answer again.

If a practical train exists, check the train before either. National rail is 39.89g CO₂e per passenger-kilometre on the same broad boundary used here, almost identical to the average electric-car figure with one person and far below flying.

You can read how the train compares with the car for petrol, diesel, hybrid and electric cars.

There is no reliable “under 300 miles, drive” rule. The vehicle, the number of people in it, the type of flight and the actual road and air distances all affect the result.

If you still need to fly

Sometimes flying is the practical option. I fly too.

If there is a realistic lower-emission alternative that does not turn the journey into an ordeal, I would take it.

If there is not, calculate the flight properly.

You can calculate the emissions from your actual flight using the same 2026 Government factors discussed here, with your departure airport, destination and cabin class.

If you then choose to fund a climate or restoration project, keep that separate from the calculation.

The flight still happened. Its emissions do not disappear because money was spent elsewhere.

The project funding supports work afterwards.

We explain that distinction in how to offset a flight properly.

Calculate my flight emissions

Flying vs driving FAQs

Sources and methodology

This article uses government, accounting and peer-reviewed scientific sources. We have not used competitor carbon calculators or commercial comparison articles as evidence.

• Department for Energy Security and Net Zero, UK Government greenhouse gas conversion factors 2026. The primary source for the car and aviation factors used throughout this article. The relevant worksheets in the full 2026 dataset are Business travel- air, WTT- business travel- air, Business travel- land, WTT- pass vehs & travel- land, UK electricity for EVs and UK electricity T&D for EVs. The rail figures are the National rail rows in Business travel- land and in WTT- pass vehs & travel- land. View the publication.
• Department for Energy Security and Net Zero, 2026 Government greenhouse gas conversion factors methodology paper. The primary source for the passenger-car methodology, electric vehicle factors, aviation factors, the 8% distance uplift, well-to-tank emissions and aviation’s non-CO₂ effects. View the methodology.
• Lee, D. S. and others, 2021, Atmospheric Environment. Peer-reviewed research on aviation’s CO₂ and non-CO₂ climate forcing, cited within the UK Government methodology. View the record.
• GHG Protocol, category 6, business travel. Authoritative accounting guidance for business travel. Used for reporting context rather than the headline numerical factors. View the guidance.
• Journey distances. Road distances are shortest practical driving routes between city centres, from OpenStreetMap routing data, rounded to the nearest 5km. Flight distances are great-circle distances between airports, calculated by C Level using the same method as our flight carbon calculator.

Exact calculations used in the headline table:

Travel option	Published journey factor	Upstream factor	Total used
UK domestic flight, average passenger	229.28g	33.50g	262.78g CO₂e/passenger-km
UK short-haul economy flight	125.76g	22.49g	148.25g CO₂e/passenger-km
UK long-haul economy flight	117.04g	24.61g	141.65g CO₂e/passenger-km
Average petrol car	161.52g	45.99g	207.51g CO₂e/vehicle-km
Average diesel car	172.65g	41.46g	214.11g CO₂e/vehicle-km
Average battery-electric car	26.86g electricity + 2.66g transmission and distribution	10.49g upstream	40.01g CO₂e/vehicle-km
National rail, average passenger	30.92g	8.97g	39.89g CO₂e/passenger-km

For cars carrying more than one person, the vehicle figure is divided by the number of occupants. All figures are averages. Actual vehicles, routes, traffic, weather, aircraft operations and driving styles can produce different results.