Rankings / Southwest Airlines
2025 report cardSouthwest Airlines
In 2025 Southwest Airlines flew 64.3 passenger-miles per gallon of jet fuel, ranking 8 of 13. That's 6% better than the all-airline figure that year. Since 2000 its figure has risen 54%.
About Southwest Airlines
Southwest has flown only Boeing 737s, and it's one of the biggest carriers in this data by passengers. It bought AirTran in 2011 and folded that flying in over the following years, so for part of that period its fuel and traffic figures include AirTran. It has no regional partners, so every flight in its figure is its own.
- 64.3passenger-miles per gallon, 2025
- 0.152 kgCO2 per passenger-mile
- 77%of seats filled
- 161seats per flight on average
The story in the figures
Southwest Airlines' passenger-miles per gallon rose 54% between 2000 and 2025, from 41.7 to 64.3. Most of that came from the aircraft: seat-miles per gallon rose 40%, while planes ran fuller, with 70% of seat-miles filled in 2000 against 77% in 2025.
The shape of the flying changed as well: the average flight went from 134 seats to 161, and the average passenger flew 514 miles per segment in 2000 and 821 in 2025. In general, larger aircraft spread fuel over more passengers, and longer flights spend a smaller share of their fuel on takeoff and climb.
Its best year was 2024, at 65.0 passenger-miles per gallon.
In 2020 the pandemic emptied the cabins: load factor dropped from 84% to 51%, and passenger-miles per gallon fell from 63.2 to 43.7. A flight burns most of its fuel whether the seats are full or not, which is why an empty year looks so bad per passenger. By 2025 the figure was 1.7% above its 2019 level.
Against the all-airline figure for 2025 (60.6), Southwest Airlines was 6.2% better. On a 1,000 mile trip that works out to 152 kg of CO2 for one passenger, from burning jet fuel only.
What one seat costs the climate
CO2 for one passenger on Southwest Airlines, from burning jet fuel only.
- 76 kgover 500 miles
- 152 kgover 1,000 miles
- 303 kgover 2,000 miles
Southwest and AirTran began reporting jointly in January 2015. In 2012 to 2014 AirTran filed its traffic under its own code while its fuel was already reported by Southwest, so those years count AirTran with Southwest.
Year-by-year figures
| Year | Passenger-miles per gallon | kg CO2 per passenger-mile | Seat-miles per gallon | Load factor | Passengers (millions) | Fuel (million gallons) | CO2 (thousand tonnes) |
|---|---|---|---|---|---|---|---|
| 2025 | 64.3 | 0.152 | 83.0 | 77.5% | 169.8 | 2,169 | 21,145 |
| 2024 | 65.0 | 0.150 | 80.8 | 80.4% | 177.6 | 2,193 | 21,386 |
| 2023 | 63.6 | 0.153 | 79.5 | 80.0% | 176.4 | 2,143 | 20,894 |
| 2022 | 64.5 | 0.151 | 77.3 | 83.4% | 161.9 | 1,922 | 18,735 |
| 2021 | 62.1 | 0.157 | 79.1 | 78.5% | 127.1 | 1,668 | 16,266 |
| 2020 | 43.7 | 0.223 | 85.0 | 51.4% | 71.5 | 1,275 | 12,432 |
| 2019 | 63.2 | 0.154 | 75.7 | 83.5% | 166.8 | 2,077 | 20,255 |
| 2018 | 63.6 | 0.153 | 76.2 | 83.4% | 167.9 | 2,097 | 20,442 |
| 2017 | 63.0 | 0.155 | 75.1 | 83.9% | 162.4 | 2,047 | 19,961 |
| 2016 | 62.5 | 0.156 | 74.3 | 84.0% | 156.2 | 1,998 | 19,478 |
| 2015 | 61.7 | 0.158 | 73.8 | 83.6% | 149.9 | 1,903 | 18,557 |
| 2014 | 59.9 | 0.163 | 72.7 | 82.4% | 142.5 | 1,803 | 17,577 |
| 2013 | 57.3 | 0.170 | 71.6 | 80.0% | 140.2 | 1,820 | 17,749 |
| 2012 | 55.4 | 0.176 | 69.0 | 80.3% | 141.7 | 1,856 | 18,095 |
| 2011 | 55.6 | 0.175 | 68.8 | 80.8% | 119.4 | 1,508 | 14,707 |
| 2010 | 54.3 | 0.180 | 68.4 | 79.3% | 114.2 | 1,439 | 14,027 |
| 2009 | 52.0 | 0.187 | 68.5 | 76.0% | 109.6 | 1,431 | 13,949 |
| 2008 | 48.6 | 0.201 | 68.3 | 71.2% | 110.9 | 1,513 | 14,753 |
| 2007 | 48.5 | 0.201 | 66.9 | 72.6% | 110.6 | 1,490 | 14,526 |
| 2006 | 48.8 | 0.200 | 66.8 | 73.0% | 103.9 | 1,388 | 13,537 |
| 2005 | 46.8 | 0.208 | 66.3 | 70.7% | 95.7 | 1,286 | 12,536 |
| 2004 | 44.6 | 0.219 | 64.1 | 69.5% | 88.8 | 1,199 | 11,690 |
| 2003 | 42.0 | 0.232 | 62.9 | 66.8% | 81.9 | 1,141 | 11,126 |
| 2002 | 40.9 | 0.238 | 62.0 | 65.9% | 80.3 | 1,111 | 10,828 |
| 2001 | 41.0 | 0.238 | 60.3 | 68.0% | 82.2 | 1,085 | 10,582 |
| 2000 | 41.7 | 0.234 | 59.1 | 70.5% | 82.2 | 1,013 | 9,881 |
The Southwest Airlines fleet
Southwest Airlines operated 803 passenger aircraft of its own in 2025. The average age was 10.7 years: 32% of the aircraft were under five years old and 17% were twenty or older. The oldest was a Boeing 737-700 built in 2001. That's the 5th youngest of the 12 airlines ranked here.
In 2006 the average age was 8.8 years across 481 aircraft. It's older now by 1.9 years, and the fleet is bigger.
On the Boeing 737-700, Southwest Airlines fits 143 seats on average, against a median of 124 at the other airlines that fly it (120 to 124). Seats on the same aircraft are one reason fuel per seat and fuel per passenger differ between airlines: the fuel burned by a given plane is much the same, and more seats share it.
Southwest Airlines aircraft by model, 2025
| Model | Aircraft | Average seats | Other airlines, median seats | Average age |
|---|---|---|---|---|
| Boeing 737-700 | 305 | 143 | 124 | 19.1 |
| Boeing 737 MAX 8 | 300 | 175 | 172 | 2.7 |
| Boeing 737-800 | 198 | 175 | 172 | 9.8 |
All the airlines are compared on the fleets page.
Neighbours in the ranking
Nearby airline results
These airlines sit nearby by passenger-miles per gallon in their last data year. Historical airlines have different end years, shown here, so this isn't a same-year ranking.
Airline references
Source: US Bureau of Transportation Statistics (BTS), Schedule P-12(a) fuel, T-100 traffic and regional Schedule T-2 filings; US EPA jet-fuel CO2 factor. See the methodology.