San Francisco to Phoenix

Between San Francisco and Phoenix, 2.4 million passengers flew nonstop in 2025, on 20 thousand flights of about 641 miles and 1.6 hours in the air. The average passenger accounted for about 107 kg of CO2 from the fuel burned, from 85 kg on Frontier Airlines to 162 kg on SkyWest Airlines.

107 kgCO2 per passenger, average
641 milesabout 1.6 hours in the air
2.4 millionpassengers in 2025
79%of seats filled

CO2 per passenger, airline by airline

Kilograms of CO2 per passenger, one way, 2025. Fuel burned only. Less is better.

San Francisco to Phoenix by airline, 2025

Airline	Share of passengers	Flights (thousands)	Main aircraft	Seats per flight	Seats filled	kg CO2 per passenger
Southwest Airlines	52%	9.9	Boeing 737 MAX 8, Boeing 737-700	164	78%	100
American Airlines	21%	3.7	Boeing 737-800, Boeing 737 MAX 8	166	80%	111
United Airlines	16%	2.8	Boeing 737-800, Boeing 737 MAX 9	170	78%	109
SkyWest Airlines	5%	2.0	Embraer 175	72	85%	162
Frontier Airlines	5%	0.7	Airbus A320neo, Airbus A321neo	200	79%	85

What explains the differences

It's number 47 of the 100 busiest city pairs by passengers, and number 68 for the lowest CO2 per mile flown (0.17 kg per passenger-mile, number 1 being the lowest). A typical route of 641 miles in this set comes out at about 107 kg, so this one is close to that.

The flights use more than one pair of airports: PHX to SFO (51%), PHX to SJC (27%), PHX to OAK (23%). The figures here cover all of them.

The airlines on this route differ by 91% per passenger. Frontier Airlines burned 1,378 gallons per flight and 159 passengers on each, and SkyWest Airlines 1,009 gallons and 61 passengers. The gap comes from how many passengers share each flight, not from fuel burned per flight. Frontier Airlines flew 79% 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 83 kg. The EPA figure is a national average for flights of that length. The measured figure for this route is 29% higher.

2019 compared with 2025

In 2019 the route carried 2.8 million passengers on 24 thousand flights. In 2025 it carried 2.4 million, down 14%, on 20 thousand flights, down 18%. The average flight had 150 seats then and 155 now, and 77% of them were filled against 79%.

CO2 per passenger was 119 kg in 2019 and 107 kg in 2025, down 10.3%. Fuel burned per flight was down 5.8% (1,415 gallons to 1,334) and passengers per flight were up 5.0% (116 to 122). The distance flown was about the same (640 miles then, 641 now).

Southwest Airlines led in both years, with 49% of passengers in 2019 and 52% in 2025. United Airlines gained the most share, 10% to 16%. American Airlines lost the most, 35% to 21%. Frontier Airlines didn't have 1% of the passengers in 2019 and now carries 5%. Allegiant Air and Mesa Airlines no longer reach 1% of passengers, having had 3% in 2019.

Airline by airline, United Airlines went from 126 kg to 109 kg per passenger (160 seats per flight to 170, main aircraft Boeing 737-900ER then and Boeing 737-800 now); American Airlines went from 122 kg to 111 kg per passenger (158 seats per flight to 166, main aircraft Airbus A321 then and Boeing 737-800 now).

The airports changed too: PHX to SFO handled 41% of the passengers in 2019 and 51% in 2025.

San Francisco to Phoenix, 2019 and 2025

Measure	2019	2025
Passengers (thousands)	2,799	2,402
Flights (thousands)	24.1	19.7
Seats filled	77%	79%
Gallons of fuel per flight	1,415	1,334
kg CO2 per passenger	119	107

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.

San Francisco to Phoenix and back: time in the air

The time in the air is almost the same each way: 91 minutes on average from San Francisco to Phoenix and 96 minutes back. A difference of 6 minutes is within what routing and congestion alone produce.

Time in the air by direction, 2025

Direction	Average minutes in the air	Flights
Phoenix to San Francisco	96.2	9,853
San Francisco to Phoenix	90.7	9,837

Fly or drive

Driving is about 750 miles by road, which we estimate as 1.17 times the straight-line distance. An average car emits about 223 kg of CO2 on the trip, at the EPA figure of 0.297 kg per vehicle-mile. Alone, that's 109% more than the 107 kg for a passenger on the flight.

With 3 people in the car, driving comes out lower per person than the flight (74 kg each, and 56 kg each for four). A larger SUV or pickup (0.394 kg per mile) would emit about 295 kg per vehicle.

CO2 per person, San Francisco to Phoenix. 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.

Routes with shared cities or nearby CO2 per mile

Airports on this route: San Francisco International Airport, San Jose International Airport, Oakland San Francisco Bay 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.