Purpose – Introducing an ecolabel for aircraft according to the ISO 14025 standard allowing to compare the environmental impact of different air travel options based on the combination of aircraft type, engine type, and seating configuration. --- Methodology – The ecolabel considers resource depletion (fuel consumption), global warming (equivalent CO2 emission, including altitude-dependent NOX and aviation induced cloudiness), local air quality (NOX), and finally, noise pollution. The emissions of each impact category are normalized against a group of reference aircraft that account for over 95% of the passenger aircraft flying today. Based on the results from a life cycle assessment (LCA), the impact categories are weighted 20%, 40%, 20%, and 20%, respectively. The four impact categories are combined into one overall rating using the information from the LCA. Seating arrangements in different travel classes are considered based on the cabin floor area occupied by each passenger. Data sources are the aircraft manufacturer's documents for airport planning, the aviation emission calculator from EMEP/EEA air pollutant emission inventory guidebook 2019, the ICAO Aircraft Engine Emissions Databank, the EASA Certification Noise Levels Database, and the SeatGuru seat map database. --- Findings – Over 140 ecolabels were calculated and showed the usefulness of the concept. General conclusions were drawn about the parameters that yield environmentally friendly air travel. When combining the ecolabels of all the aircraft in an airline's fleet, even the comparison between airlines is possible. --- Research Limitations – The ecolabel cannot compare travel options that include one or more stopovers at different airports. However, different methods are proposed on how booking systems could be extended to offer a comparison based on the ecolabel approach. --- Practical Implications – Passengers understand that they should select a flight on the shortest possible route and select the best combination of aircraft and airline based on the ecolabel. Airlines that operate a modern fleet, have tight seating in a single (economy) class, and are known for their high load factor, are better for the environment. Obviously, a ticket in the economy class should be booked if the cabin features more than one class. --- Social Implications – The ecolabel gives a foundation for a general discussion about different travel options based on neutral scientific methods and data. The impact categories are defined such that a comparison between different modes of transportation is also possible. --- Originality – So far, an ecolabel has not been defined and applied to this level of detail and scientific rigor.