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Rankings / Routes / Los Angeles to San Francisco

2025 flights

Los Angeles to San Francisco

Between Los Angeles and San Francisco, 8.9 million passengers flew nonstop in 2025, on 91 thousand flights of about 337 miles and 56 minutes in the air. The average passenger accounted for about 75 kg of CO2 from the fuel burned, from 48 kg on Frontier Airlines to 93 kg on SkyWest Airlines.

8.9 million passengers flew between Los Angeles and San Francisco in 2025, more than on any other city pair in this data, and that's still 30% fewer than the 12.7 million in 2019.

At 337 miles it's also one of the costliest routes per mile. The average passenger accounts for 75 kg of CO2, 73% above what the EPA's default factor would give for a flight this short (43 kg), because a climb costs about the same fuel on 337 miles as on 1,000 and here it's a big share of the whole. The regional jets make it more obvious: SkyWest passengers account for 93 kg on a 75-seat jet, Frontier passengers for 48 kg on a 201-seat Airbus.

  • 75 kgCO2 per passenger, average
  • 337 milesabout 56 minutes in the air
  • 8.9 millionpassengers in 2025
  • 73%of seats filled

CO2 per passenger, airline by airline

CO2 per passenger by airline, Los Angeles to San FranciscoBar chart of kilograms of CO2 per passenger on each airline between Los Angeles and San Francisco in 2025.020406080Frontier Airlines48 kgSpirit Airlines58 kgAlaska Airlines64 kgUnited Airlines64 kgDelta Air Lines67 kgAmerican Airlines75 kgSouthwest Airlines78 kgHorizon Air86 kgSkyWest Airlines93 kg
CO2 per passenger by airline, Los Angeles to San FranciscoBar chart of kilograms of CO2 per passenger on each airline between Los Angeles and San Francisco in 2025.0255075Frontier Airlines48 kgSpirit Airlines58 kgAlaska Airlines64 kgUnited Airlines64 kgDelta Air Lines67 kgAmerican Airlines75 kgSouthwest Airlines78 kgHorizon Air86 kgSkyWest Airlines93 kg
Kilograms of CO2 per passenger, one way, 2025. Fuel burned only. Less is better.
Los Angeles to San Francisco by airline, 2025
AirlineShare of passengersFlights (thousands)Main aircraftSeats per flightSeats filledkg CO2 per passenger
Southwest Airlines47%42.9Boeing 737-700, Boeing 737 MAX 815165%78
United Airlines19%13.0Boeing 737-800, Airbus A320-20016083%64
SkyWest Airlines15%21.4Embraer 1757585%93
Delta Air Lines7%4.7Boeing 737-800, Boeing 737-900ER16481%67
Frontier Airlines4%1.9Airbus A320neo, Airbus A321neo20184%48
Horizon Air3%4.6Embraer 1757686%86
American Airlines1%1.1Boeing 737-800, Airbus A32117570%75
Spirit Airlines1%0.9Airbus A320neo, Airbus A320-20018075%58
Alaska Airlines1%0.7Boeing 737-800, Boeing 737-900ER16484%64

What explains the differences

It's number 1 of the 100 busiest city pairs by passengers, and number 88 for the lowest CO2 per mile flown (0.22 kg per passenger-mile, number 1 being the lowest). A typical route of 337 miles in this set comes out at about 70 kg, so this one is 7.7% above it.

The flights use more than one pair of airports: SFO to LAX (30%), SJC to LAX (10%), SFO to SNA (10%). The figures here cover all of them.

The airlines on this route differ by 91% per passenger. Frontier Airlines burned 837 gallons per flight and 168 passengers on each, and SkyWest Airlines 604 gallons and 64 passengers. The gap comes from how many passengers share each flight, not from fuel burned per flight. Frontier Airlines flew 84% full here against 85% for SkyWest Airlines, flying mostly Airbus A320neo against Embraer 175.

For comparison, the EPA default factor for a flight of this length (0.129 kg per passenger-mile) would give 43 kg. The EPA figure is a national average for flights of that length. The measured figure for this route is 73% higher.

2019 compared with 2025

In 2019 the route carried 12.7 million passengers on 130 thousand flights. In 2025 it carried 8.9 million, down 30%, on 91 thousand flights, down 30%. The average flight had 130 seats then and 133 now, and 75% of them were filled against 73%.

CO2 per passenger was 77 kg in 2019 and 75 kg in 2025, down 1.7%. Fuel burned per flight was down 1.5% (767 gallons to 755) and passengers per flight were up 0.2% (98 to 98). The distance flown was about the same (335 miles then, 337 now).

Southwest Airlines led in both years, with 54% of passengers in 2019 and 47% in 2025. SkyWest Airlines gained the most share, 7% to 15%. Southwest Airlines lost the most, 54% to 47%. Frontier Airlines didn't have 1% of the passengers in 2019 and now carries 4%. Compass Airlines and JetBlue no longer reach 1% of passengers, having had 9% in 2019.

Airline by airline, Horizon Air went from 106 kg to 86 kg per passenger (76 seats per flight to 76, main aircraft Embraer 175 in both years); Southwest Airlines went from 72 kg to 78 kg per passenger (146 seats per flight to 151, main aircraft Boeing 737-700 in both years).

Los Angeles to San Francisco, 2019 and 2025
Measure20192025
Passengers (thousands)12,6848,918
Flights (thousands)130.091.3
Seats filled75%73%
Gallons of fuel per flight767755
kg CO2 per passenger7775
CO2 per passenger by airline, 2019 and 2025, Los Angeles to San FranciscoBar chart of kilograms of CO2 per passenger on Los Angeles to San Francisco for each major airline in 2019 and in 2025.0255075100Southwest Airlines 201972 kgSouthwest Airlines 202578 kgUnited Airlines 201971 kgUnited Airlines 202564 kgSkyWest Airlines 2019103 kgSkyWest Airlines 202593 kgDelta Air Lines 201976 kgDelta Air Lines 202567 kg
CO2 per passenger by airline, 2019 and 2025, Los Angeles to San FranciscoBar chart of kilograms of CO2 per passenger on Los Angeles to San Francisco for each major airline in 2019 and in 2025.050100Southwest Airlines 201972 kgSouthwest Airlines 202578 kgUnited Airlines 201971 kgUnited Airlines 202564 kgSkyWest Airlines 2019103 kgSkyWest Airlines 202593 kgDelta Air Lines 201976 kgDelta Air Lines 202567 kg
Kilograms of CO2 per passenger on the airlines that flew the route in both years. 2019 figures use that year's filings and estimated aircraft fuel rates, with type-average replacements for missing or outlying filings as described in the methodology. Less is better.

Los Angeles to San Francisco and back: time in the air

The time in the air is almost the same each way: 56 minutes on average from Los Angeles to San Francisco and 57 minutes back. A difference of 1 minute is within what routing and congestion alone produce.

Time in the air by direction, 2025
DirectionAverage minutes in the airFlights
San Francisco to Los Angeles57.045,670
Los Angeles to San Francisco55.745,586

Fly or drive

Driving is about 394 miles by road, which we estimate as 1.17 times the straight-line distance. An average car emits about 117 kg of CO2 on the trip, at the EPA figure of 0.297 kg per vehicle-mile. Alone, that's 55% more than the 75 kg for a passenger on the flight.

With 2 people in the car, driving comes out lower per person than the flight (59 kg each, and 29 kg each for four). A larger SUV or pickup (0.394 kg per mile) would emit about 155 kg per vehicle.

CO2 per person by way of travel, Los Angeles to San FranciscoBar chart of kilograms of CO2 per person flying, driving or taking the train between Los Angeles and San Francisco.0255075100Flight, average75 kgCar, driver alone117 kgCar, 2 people59 kgCar, 4 people29 kg
CO2 per person by way of travel, Los Angeles to San FranciscoBar chart of kilograms of CO2 per person flying, driving or taking the train between Los Angeles and San Francisco.050100Flight, average75 kgCar, driver alone117 kgCar, 2 people59 kgCar, 4 people29 kg
CO2 per person, Los Angeles to San Francisco. Driving figures divide one car's emissions between the people in it. See flying vs driving for other trip lengths.

Flights are listed under the airline that operates them, so regional flying appears under the regional. How the CO2 and drive figures are worked out is in the methodology.

What to take from it

Southwest carries 47% of the passengers but its flights are the emptiest here, 65% full against 83% for United, which is why its 78 kg sits above United's 64 kg. SkyWest and Horizon together now carry 19% of passengers, up from 8% in 2019.

This is one of the few routes where the car can win. Driving alone, 394 miles of road, emits 117 kg, 55% more than the flight. With a second person in the car it's 59 kg each, 22% less.

Routes with shared cities or nearby CO2 per mile

Los Angeles to Las Vegas53 kg CO2 per passenger over 227 milesNew York to Los Angeles406 kg CO2 per passenger over 2,465 milesLos Angeles to Dallas-Fort Worth171 kg CO2 per passenger over 1,222 milesLos Angeles to Denver130 kg CO2 per passenger over 850 milesNew York to Detroit106 kg CO2 per passenger over 499 milesNew York to Charlotte117 kg CO2 per passenger over 541 milesNew York to Raleigh-Durham102 kg CO2 per passenger over 427 miles

Airports on this route: San Francisco International Airport, Los Angeles International Airport, San Jose International Airport, John Wayne Airport, Oakland San Francisco Bay Airport, Hollywood Burbank Airport.

Airport and airline references

Source: US Bureau of Transportation Statistics (BTS), T-100 traffic and Schedule T-2 fuel filings; US EPA transport emission factors. See the methodology.

See all routes, or how the airlines compare overall on the airline pages.