Fly.Green is supporting you to plan a sustainable travel, but we are not responsible for your booking and your offset. We will show you, what options for travel are available and how they impact the environment – your booking and payment will be made directly with a travel provider, which you choose via our site. Since we do not have access to your travel data, we recommend to ask your travel provider in case of questions about your flight.

Offsett and payment will be handled directly from atmosfair. Please contact atmosfair directly in case of any questions concerning your offset.

Do you still have questions? Please review our FAQs or contact us via email:



What is is an online travel agency. They combine flights, trains, and buses into unique itineraries to offer you more options and better deals. Every layover which isn’t connected by the carriers can be protected by their Guarantee.’s Customer Support agents are here for you 24/7 when you’re traveling. At other times you can reach them at particular hours, depending on your level of Service.
They offer the usual extras like seats or baggage, but you can also request, e.g., special assistance, sports equipment, or a pet. With most bigger airlines, they’ll also help you to save time at the airport by checking you in online.

How many passengers are allowed per booking?

The maximum number of passengers per booking depends on the airline’s policy. If they allow more passengers than 9, then will allow it. It is not possible to link different bookings together automatically.


Why do prices at include flight AND offset?

We believe, that every flight should be compensated according to CDM Gold Standard, until innovation allows CO₂ neutral flights. In order to give you full transparency at all times, we decided to provide you with total cost for your trip – flight AND offset. Often times you will find the environmentaly friendliest flight to be amongst the cheaper offers. This is in parts also due to the fact, that the offset amount for a clean flight ist lower.

Why do you have a “cheapest” option as sorting criteria? Isn’t about reducing the environmental impact?

We decided to give you full transparency and we trust in the travelers ability to make a qualified choice. But truth to be told, we did have heated discussion about this. So, should you choose to book a flight with higher emissions, you will have good reasons to do so… and you would certainly be paying the higher offset. Recent research shows, a significant adoption of “emissions-aware flight search” could encourage a real reduction in aviation emissions. It also shows a remarkable willingness-to-pay of travelers to avoid emissions, being it to choose different flight times, switch to a nearby airport or to pay a higher ticket price. This is very encouraging for us!

Are flights offered by cheaper than other offers on the market?

It depends. We made a lot of comparisions of prices from with flights offered directly from airlines or on other search platforms. It looks like it is very much depending on the route and amount of transfers you are going to make. Feel free to compare!

Search results

How do you create the “qualified choice”?

The qualified choice consideres 50% emissions (so the cleanest flight will be ranked highest), 30% total travel time (the faster, the higher in the ranking) and 20% price. We decided to provide you with this option, as sometimes the cleanest flight of your search might have a very long travel time or will be very expensive. So this sorting is to support your decision making.

How do we calculate CO₂ amount saved and % to average?

The amount of CO₂ saved is the difference between the AVERAGE OF ALL FLIGHTS WE FOUND FOR YOUR SEARCH and THE FLIGHT OF YOUR CHOICE.

Any %-measures we display do also relate to the AVERAGE and a specific flight. The AVERAGE is based on all flight results of your specific search and does include flights with overnights and long stopovers.

Why and how do you come up with CO₂ usage of a light bulb, a washing machine and a car?

Flying is a big contributor to global warming. We are not against travel at all, but we believe flying should be planned carefully and under consideration of its environmental impact. This is why we choose simplistic, everyday measures to illustrate the potential of savings in emission by making a qualified choice.

Our calculation is based on these parameters :

Low energy light (18W) is causing 66kg CO₂ per year with a 24/7 usage.

Washing mashine (EU energy label A-rated gives an average consumption at 40°C using a 2kg load to be 0.63 kWh) is causing 51kg CO₂ per year with 187 washes per year.

Small family car produces 175kg CO₂ per 1000 km.

In order to keep the effects of climate change within sustainable limits, the participating parties agreed at the UN Climate Conference in 2015 in Paris to limit average global warming to well below 2° C compared to pre-industrial levels.

Most scientists argue that it is necessary to limit global warming to 1.5° C because, if the temperature rises above this, dangerous tipping points in the global climate system can no longer be avoided.

In a special report at the end of 2018, the Intergovernmental Panel on Climate Change (IPCC) calculated a global emissions budget of around 420 billion t CO₂ for a 1.5° C target from 2018 onwards. This amount applies to a scenario in which the 1.5° C target is reached with a probability of 67%. Unfortunately, an IPCC calculation for a higher probability of reaching the target (e.g. 95%) does not exist.

If we assume, as many countries worldwide and the EU do, that the global economy has to be completely decarbonized by 2050, and with an assumed average world population of 8.8 billion people in the period from 2018 to 2050, this means that every person on this earth would be entitled to a climate-friendly budget of about 1.5 t CO₂ per year on average in order to reach the maximum warming target of 1.5° C. This average can be distributed irregularly, so that in the beginning, a person would have more than 1.5 t CO₂ annually, but later on, correspondingly less.

The industrialised countries are far from this goal. In 2005, the yearly carbon dioxide emissions in the USA were almost 16.1 tonnes per capita, in Germany 9.2 tonnes, and in China already at 8.0 tonnes (see UN Statistikbüro UNSTAT).

Emission Data

Why does every flight have a specific footprint and how is it calculated?

The calculations include the effects of the different pollutants according to the latest scientific knowledge, especially to their impact at high altitude. At the same time every calculation has its limits: one can only calculate a presumably fuel consumption of a given flight. A plane may have to take a detour because of fog, the load may be higher or lower than average. Variations like these cannot be included in the calculation.

Not all flights are the same. It is obvious that a flight from Frankfurt to Honolulu causes more environmental damage than a flight from Hamburg to Cologne. In short, a number of factors other than the distance of a flight must be taken into account to calculate the impact of one single air-passenger on the world’s climate.

For instance, flight altitude, aircraft type, the number of seats on board and how many of them are occupied all are a very important factor in the calculation of emissions.

The emissions calculator contains stored data on all relevant information. Because the calculator uses data sets of high scientific quality, the result can be considered “as precise as possible”. The data and the calculation method on which they are based have been verified by the German Federal Environmental Agency.

Detailed information on atmosfair’s emission calculator can be found here.

Why does the emissions calculator only make its calculations using carbon dioxide? Airplanes also emit other pollutants that harm the climate.

Carbon dioxide, nitrogen oxide, soot and sulphur particles as well as water vapour from aircraft engines affect the climate with different durations and intensities. But because all of these together add to the layers of greenhouse gases in the atmosphere, atmosfair calculates them approximately in terms of carbon dioxide.

In sum, the different emissions in high flight altitudes of more than nine kilometres have an effect that is about three times as strong as the carbon dioxide of a flight.

In order to appropriately represent the climate impact of all flight emissions, the atmosfair emissions calculator multiplies the CO₂ emissions emitted at altitudes over 9 km with the global average multiplicator of 3. This multiplicator results when the global warming potential of all non-CO₂ effects is integrated and discounted over 100 years (UNFCC) and (David Lee et al., “Transport impacts on atmosphere and climate: Aviation”, in atmospheric environment (44), 2010).

How exact are the results of the emissions calculator?

It is clear that only the likely climate gas emissions of a flight can be calculated. If the aircraft must circle due to icy runways or if the occupancy is exceptionally high or low, the calculator cannot take this into account. In this respect, the emissions calculator’s results cannot be as exact as directly measuring the emissions on-site. However, in general, its results should correspond well with reality due to the range and quality of the underlying data.

You can find a discussion of the methods and the accuracy of results in the 
atmosfair emissions calculator documentation.

Is it important whether I fly on a scheduled or a charter flight?

On a charter aircraft, more passengers typically fly than in a scheduled plane of the same size. Due to the higher utilisation of the charter plane, a person travelling on a packaged tour has less of an impact on the climate than an individual traveller.

You can find detailed information on the topic “capacity utilisation” in the 
atmosfair emissions calculator documentation.

Why is there a difference between business or economy class?

The seats are wider in business class. As a result, fewer people can be seated in the same amount of space as in economy class. Because the fuel consumption per person decreases when more people can be seated in an aircraft, the atmosfair contribution for a seat in business class is higher on average than the emissions contribution for a seat in economy class. Same applies for first class and premium economy. As a consequence, passengers in economy class donate somewhat less and passengers in first, business or premium economy somewhat more than average.

You can find detailed information on the topic “flight class” in the 
atmosfair emissions calculator documentation.

Do short-distance flights cause more emissions than long-­distance flights?

Basically, it’s the case that the longer the flight is, the more detrimental its impact on the climate. This is because for each additional kilometre flown, more fuel is used and thus more greenhouse gases are emitted. However, if we consider the relative consumption per 100 kilometres of the flight route, this relationship changes.

On the one hand, aircrafts fly along short-distance routes up to around 400-600 kilometres in low atmospheric altitudes, in which no contrails or ice clouds are created. The ozone formation from nitrogen oxide is less here than in altitudes above around 9 kilometres. Finally, the kerosene tanks of an aircraft that must only cover 500 kilometres are much lighter than those of one that will cover a long-distance flight. On the other hand, the kerosene-intensive ascent of a short-distance flight carries much more weight than it does on an intercontinental flight.

You can find detailed information on the topic “distances” in the atmosfair emissions calculator documentation.

Do different airlines have different carbon efficiencies?

The atmosfair Airline Index compares and ranks the carbon efficiency of the 200 largest airlines of the world. The formula contain for every flight the aircraft type, engines, winglets, seating and freight capacity as well as load factors for both passengers and co-loaded freight. Using detailed sources from authorities and official statistics, specialised data service providers and computer models used by aircraft engineers, the CO₂ emissions of an airline can be calculated at an error margin of less than two percent.

The objective of atmosfair is, to make climate efficiency a factor of competition among the airlines. It can only benefit climate protection, if the CO₂-performance of the various airlines are brought to light and into the public.

Car drivers have long been able to inform themselves about the CO₂ emissions of a car before purchasing it; however, air passengers are left in the dark when it comes to choosing the most climate-friendly airline. The Airline Index sheds light upon this matter. In the index, every airline receives between 0 and 100 efficiency points, differentiated by flight length (short, medium and long).


How is the atmosfair offsetting contribution calculated?

For this, there are two components that come together: firstly the CO₂ emissions of a flight and secondly the costs of saving this amount in a climate protection project.

The CO₂ emissions of a flight are calculated using the atmosfair emissions calculator. With this, other pollutants like nitrogen oxide or soot particles besides pure CO₂ emissions are also included that warm the climate in addition to CO₂. For this reason, the values for a flight with atmosfair are higher than with most other emissions calculators.

The emissions calculator sets a price of 23 euros per tonne of carbon dioxide. These 23 euros are currently needed in order to save a tonne of CO₂ in high-quality climate protection projects in developing countries. An example can illustrate how the price of saving a tonne of CO₂ comes into being:

On the roofs in an outer settlement of Cape Town in South Africa, all warm water is normally heated using diesel cookers. This is emissions-intensive and moreover expensive. atmosfair arranges the installation of solar panels with a project operator in South Africa; these panels are mounted onto house roofs and heat the water directly. To implement the 50 installations, the operator receives the 23,000 € required from atmosfair. In the ten years of the contractual term, 40,000 litres of diesel will be saved each year and thus the climate will be saved 1,000 tonnes of carbon dioxide (CO₂) in total. Thus, in this project, atmosfair can save 1,000 tonnes of CO₂ with 23,000 €. atmosfair concludes a contract with the project operator, after which the operator receives 23 € from atmosfair for a demonstrably saved tonne of CO₂, and pays the first 15,000 € as an advance payment so that the project operator can begin. A UN-accredited auditor who is liable for any mistakes must complete the verification of the successful  CO₂ reduction.

The principle of saving emissions caused somewhere else underlies the economic insight that it is less expensive to avoid damage than to repair it. In other words, once a storm destroys a settlement the costs for rebuilding it are higher than the costs of climate gas avoidance that would not have allowed the storm to arise in the first place. Thus, the emissions contribution of a long-distance flight does not reflect the costs for the “repair” of the damage caused to the climate, but rather the amount that is required to avoid these emissions somewhere else.

Your choice matters

Choose a cleaner flight and save emissions of up to 15 years keeping a light on

Other information
Sustainable Travel

There are great opportunities to combine travel and sustainability. Here we provide you with insights and news around sustainable travel

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Emission Data

Airplanes emit several pollutants that harm the climate with different durations and intensities. We calculate them approximately in terms of carbon dioxide

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About Us

Find out how Fly.Green works, why we think it worth making this your preferred flight search engine, and who we are

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You can help us by providing us with an honest feedback. Our goal is to continuously improve our service to establish carbon as a part of every online search.

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