Our sustainable aviation fuel (SAF) program

At United, our purpose of “Connecting People. Uniting the World.” extends beyond just getting you to your next destination. Our commitment to mitigating our environmental impact means understanding our climate impact, holding ourselves accountable, and working to chart a more sustainable course for the future of air travel.

We recognize the role we play in contributing to climate change and our responsibility in solving it. That’s why we’ve embraced the goal of reducing our greenhouse gas (GHG) emissions 100% by 2050.

Reducing emissions by 100%

How you can help

Reducing emissions by 100% by 2050 starts with fuel

Sustainable aviation fuel (SAF) is a lower-carbon alternative to normal jet fuel that can be used to fuel existing aircraft without making significant modications to the aircraft and its engines. SAF used by United has up to 85% lower GHG emissions than regular jet fuel when we count all of its emissions, all the way from how it’s made and delivered to the airport, to when we use it (these are called ‘lifecycle emissions’). This does not mean our current use of SAF reduces our carbon footprint by 85%, however. We still have a long way to go to reducing our emissions by 100% by 2050, as currently only 0.1% of our overall fuel is SAF.

Conventional jet fuel releases new carbon into the atmosphere

1. Extract

Crude oil is extracted from the ground

2. Refine

Crude is refined into jet fuel, a carbon-intensive process

3. Consume

Finished jet fuel is used to fly aircraft

Producing and using SAF can lower the lifecycle emissions compared to regular jet fuel a number of ways, such as by reusing a waste material so the waste doesn’t create more emissions when thrown out, by using a plant-based material that has captured GHGs, or capturing and using some of the CO₂ in the air.

Sustainable aviation fuel emits up to 85% less carbon on a lifecycle basis

1. Collect

Renewable or waste materials are collected

2. Convert

Collected materials are converted to fuel with a process using renewable energy if possible

3. Use

Finished SAF is used to power aircraft more sustainably

Using more SAF helps us not only to reach our goal to go net zero by 2050, but also our plan to decrease our carbon intensity by 50% from 2019 to 2035. We were the first airline to use SAF in regular operations on an ongoing basis, and the first U.S. airline to create a sustainability-focused venture fund to invest, in part, in SAF production.

2009
First U.S. airline to test SAF.

2015
First investment in a SAF technology.

2016
First U.S. airline to use SAF for regularly scheduled flights.

2020
Commitment to reduce emissions by 100% by 2050.

2021
First passenger flight using 100% SAF in one engine.

2022
First U.S. airline to announce expansion of SAF use at an international airport (AMS).

How you can help

Here’s how you can play a role in helping us reach our sustainability goals.

During your flight search

When you see green shading around a flight, it means we’ve estimated this to be a lower-carbon option on a per-passenger basis than other flights with carbon emissions shown for your itinerary. This is based on the share of the flight’s estimated carbon emissions for an economy seat, which can vary based on things like flight time, aircraft type/fuel efficiency, and that flight’s total passengers, bags, and cargo. The estimates displayed are not per-aircraft carbon emissions. You are not guaranteed your selection of flight(s) as operational issues may cause routing and/or equipment changes. Our FAQs have more about how United calculates your emissions and third-party validation.

Contribute to United’s sustainable flight account

We’re giving customers the option to join our efforts in helping to create a more sustainable future of air travel. Contributions to United’s sustainable flight account will be used by United to invest in Sustainable Aviation Fuel (SAF) research, technology and production and other initiatives focused on helping to reduce carbon emissions in aviation, as well as for purchases of SAF.

We believe SAF production, if brought to scale, will help to reduce carbon emissions in aviation. We currently believe that SAF is the most scalable solution to help reduce carbon emissions in air travel. Today it’s made from things you’d otherwise get rid of like used cooking oil, household trash, or forest waste. It can produce fewer greenhouse gas emissions than conventional jet fuel on a lifecycle basis. While United has invested in the future production of over 5 billion gallons of SAF – the most of any airline in the world – today, SAF production remains very limited. And it’s expensive, so every dollar counts.

Contributions made during booking to United’s sustainable flight account will be used by United to invest in SAF research, technology and production and other initiatives focused on helping to reduce carbon emissions in aviation, as well as for purchases of SAF. Customer contributions are not directly linked to fuel purchases for booked flights and will not result in emissions reductions on booked flights. Sustainable flight account and other decarbonization initiative contributions are nonrefundable and non-tax deductible. Customers will not have any interest in United’s investments made with customer contributions, and customers will not participate in any gains or losses associated with United’s investment other companies or funds. Additional terms & conditions apply. Learn more about United’s Sustainable Aviation Fuel program.

Sustainable Aviation Fuel Program FAQs

SAF costs significantly more to produce than regular jet fuel for many reasons, including higher costs to make it and limited supplies of the ingredients that go into SAF. We call this increased cost the ‘green premium.’ While contributions today are not likely to result in widespread, immediate use of SAF, United will use your contributions to help pay for SAF in future purchase agreements, as well as towards our investments in future SAF production or other projects that we hope will help us meet our goals, including work done through United Airlines Ventures.
Yes. Because this fuel is considered a ‘drop-in’ fuel, no infrastructure or aircraft engine modifications are necessary. However, current regulations still require SAF to be blended with regular jet fuel, and United meets these requirements. It’s just as safe to fly on an aircraft using 100% regular jet fuel as it is on one using a SAF blend, as both types meet the same technical and safety requirements. In fact, we demonstrated the safety of flying with SAF when we conducted the first passenger flight using 100% SAF in one engine, and regular jet fuel in the other engine, in December 2021.
Your emissions are displayed as a standard unit in greenhouse gas (GHG) accounting measurement, which is widely used by scientists and carbon calculators. CO₂e (‘e’ for ‘equivalent’) accounts for carbon dioxide and as well as other GHGs.
United works with a variety of SAF producers, two of whom are producing SAF at a commercial scale today and providing SAF to United:
- SAF is not used on all flights. Since 2016 United has received SAF from World Energy, which produces SAF from waste fats, oils, and greases. World Energy’s SAF production facility is near Los Angeles International Airport, where the SAF is delivered to United. United flights from LAX are fueled with a blend of SAF and conventional fuel from World Energy.
- In 2022 United began buying SAF internationally, a first for a U.S. airline, from Neste. Neste’s SAF is also produced from waste fats, oils, and greases, and is delivered from Porvoo, Finland to United at Amsterdam Airport Schiphol. Certain United flights from Amsterdam, generally (but not always) one flight a day, are fueled with a blend of SAF and conventional fuel from Neste.
SAF is not used on all flights. Starting in October 2022, only United’s flights departing from LAX, and certain United flights departing from AMS, were fueled with a blend of SAF and conventional jet fuel. In 2023, United doubled the number of SAF delivery locations, bringing a blend of SAF and conventional jet fuel to United flights operated out of LHR and SFO. In 2024, United was the first U.S. carrier to bring SAF to ORD.
The International Air Transport Association (IATA) supports aviation with global standards for airline safety, security, efficiency and sustainability. We calculate emissions on a per-passenger basis for your flight using IATA’s 2022 guidelines, with actual United data at the flight level rather than company-wide or industry-wide averages for greater accuracy and to drive transparency globally. This method is not the same as the methodology used by other flight search providers, including Google, so those estimates may be different. Here’s how we do it:
1. We calculate the typical total emissions for a flight from United’s fuel use records for that flight. This value is scaled up by ~3% to include non-CO₂ emissions, fuel use at the gate, and for other emission sources like our electricity use.
2. We plug in the typical passengers, bags, and cargo on board using United’s weight and balance records for that flight.
3. We divide the emissions to individual customers based on the number of seats and amount of bags they bring.
No. The calculations provided are made by United and are not intended to be used by passengers or corporate customers in any formal GHG emissions inventory, report, or disclosure. Because these are estimates, United does not guarantee the actual carbon emissions of the actual flight will be the same. Carbon emissions may differ from the displayed estimate based on various factors such as weather, operational disruptions, air traffic control delays, actual flight time, route, aircraft type, and fuel use. In addition, carbon emissions shown are only for economy seats. The emissions are higher for premium cabin seats because they take up more space on the aircraft.
The estimated emissions for flights provided are only of CO₂ emissions. Jet fuel combustion, including the combustion of SAF/conventional jet fuel blends, also results in other emissions including nitrous oxides (NOx) and particulate matter. Some research suggests these emissions could impact climate change, although the science on this point is unclear.

Disclaimer and other important terms and conditions

*Terms and conditions provided within the flight booking tool apply to sustainable flight account contributions. United will collect all contributions in a designated account, the “sustainable flight account”. United or one of its wholly-owned subsidiaries will use 100% of the funds in this account invest, directly or indirectly, in start-ups or other ventures focused on helping to reduce carbon emissions in aviation through sustainable aviation fuel ("SAF”) research, technology and production and other initiatives focused on reducing carbon emissions in aviation, as well as for purchase of SAF. Contributions to the account may invest in entities in which United holds or may obtain an equity or other financial interest or with which United has or may in the future do business. Contributions are nonrefundable and non-tax deductible. United retains the right, in its sole discretion, to make decisions regarding the use of sustainable flight account contributions. Participants contributing retain no legal interest in the sustainable flight account or funds therein, which belongs entirely to United, or in any investments, financings, or purchases (including SAF and the environmental attributes from SAF) made by United or any of its subsidiaries with contributed funds. Participants contributing to the sustainable flight account will not participate in any gains or losses associated with United’s investment in any companies or funds. There is no assurance as to the timing of the use of sustainable flight account contributions. For example, investments or purchases may be delayed for any reason, including but not limited to because of delays in funding of United’s investments from the account, the unavailability of sufficient quantities of SAF, or the price of SAF. Our estimates of carbon emissions are estimates only. Actual carbon emissions for any flight may vary. In addition, our method of calculating carbon emissions may differ from other methods that might produce different emissions estimates. Of the flights with estimated carbon emissions shown, the results that are shaded green indicate those that have lower estimated carbon emissions on United and United Express flights only, and such estimates are based on a per-passenger basis for an economy class seat. Emissions estimates for premium seats are higher and are displayed on a per-seat type basis once a premium fare is selected. Estimated carbon emissions may change if your seat assignment changes, a substitution of aircraft occurs or the flight’s routing changes. Contributions the sustainable flight account are not directly linked to fuel purchases and will not result in emissions reductions on booked flights. Contributions are not a pre-purchase of air transportation and no travel credit or refund will be provided for such contribution in connection with a canceled or delayed flight or otherwise. For further information about our environmental impact, review United's Corporate Responsibility Report and Annual Report on Form 10-K, available at https://www.united.com/ual/en/us/fly/company/global-citizenship/environment.html and ir.united.com.

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Our sustainable aviation fuel (SAF) program

Reducing emissions by 100% by 2050 starts with fuel