Seattle to Phoenix

Between Seattle and Phoenix, 1.8 million passengers flew nonstop in 2025, on 15 thousand flights of about 1,107 miles and 2.5 hours in the air. The average passenger accounted for about 164 kg of CO2 from the fuel burned, from 133 kg on Frontier Airlines to 252 kg on SkyWest Airlines.

164 kgCO2 per passenger, average
1,107 milesabout 2.5 hours in the air
1.8 millionpassengers in 2025
83%of seats filled

CO2 per passenger, airline by airline

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

Seattle to Phoenix by airline, 2025

Airline	Share of passengers	Flights (thousands)	Main aircraft	Seats per flight	Seats filled	kg CO2 per passenger
Alaska Airlines	46%	5.7	Boeing 737-900ER, Boeing 737 MAX 9	174	85%	145
Delta Air Lines	24%	3.5	Boeing 737-800, Boeing 737-900ER	157	79%	184
Southwest Airlines	16%	2.1	Boeing 737 MAX 8, Boeing 737-700	165	85%	146
SkyWest Airlines	7%	2.0	Embraer 175	72	87%	252
Frontier Airlines	4%	0.5	Airbus A320neo, Airbus A321neo	192	79%	133
Envoy Air	2%	0.7	Embraer 175	76	91%	243

What explains the differences

It's number 77 of the 100 busiest city pairs by passengers, and number 45 for the lowest CO2 per mile flown (0.15 kg per passenger-mile, number 1 being the lowest). A typical route of 1,107 miles in this set comes out at about 165 kg, so this one is close to that.

The airlines on this route differ by 89% per passenger. Frontier Airlines burned 2,068 gallons per flight and 151 passengers on each, and SkyWest Airlines 1,612 gallons and 62 passengers. The gap comes from how many passengers share each flight, not from fuel burned per flight. Frontier Airlines flew 79% full here against 87% 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 143 kg. The EPA figure is a national average for flights of that length. The measured figure for this route is 15% higher.

2019 compared with 2025

In 2019 the route carried 1.8 million passengers on 12 thousand flights. In 2025 it carried 1.8 million, up 2%, on 15 thousand flights, up 17%. The average flight had 165 seats then and 150 now, and 88% of them were filled against 83%.

CO2 per passenger was 161 kg in 2019 and 164 kg in 2025, up 2.4%. Fuel burned per flight was down 11.2% (2,385 gallons to 2,118) and passengers per flight were down 13.3% (145 to 126). The distance flown was about the same (1,107 miles then, 1,107 now).

Alaska Airlines led in both years, with 38% of passengers in 2019 and 46% in 2025. Southwest Airlines lost the most, 21% to 16%. SkyWest Airlines and Frontier Airlines and Envoy Air didn't have 1% of the passengers in 2019 and now together carry 14%. American Airlines no longer reaches 1% of passengers, having had 21% in 2019.

Airline by airline, Delta Air Lines went from 190 kg to 184 kg per passenger (146 seats per flight to 157, main aircraft Airbus A320-200 then and Boeing 737-800 now); Alaska Airlines went from 147 kg to 145 kg per passenger (173 seats per flight to 174, main aircraft Boeing 737-900ER in both years).

Seattle to Phoenix, 2019 and 2025

Measure	2019	2025
Passengers (thousands)	1,808	1,840
Flights (thousands)	12.5	14.7
Seats filled	88%	83%
Gallons of fuel per flight	2,385	2,118
kg CO2 per passenger	161	164

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.

Seattle to Phoenix and back: time in the air

Flights from Phoenix to Seattle spent 158 minutes in the air on average in 2025, against 143 minutes from Seattle to Phoenix: 15 minutes longer, 10% more. That's the westbound direction, into the prevailing west-to-east winds, which at flight levels often blow at well over 50 miles an hour.

At this route's average burn of about 845 gallons per flight hour, those extra minutes cost about 208 gallons per flight, which is about 1.7 gallons or 16 kg of CO2 for each passenger on the slower direction. The route figure above averages both directions.

Time in the air by direction, 2025

Direction	Average minutes in the air	Flights
Phoenix to Seattle	157.8	7,342
Seattle to Phoenix	143.0	7,320

Fly or drive

Driving is about 1,295 miles by road, which we estimate as 1.17 times the straight-line distance. An average car emits about 385 kg of CO2 on the trip, at the EPA figure of 0.297 kg per vehicle-mile. Alone, that's 134% more than the 164 kg for a passenger on the flight.

With 3 people in the car, driving comes out lower per person than the flight (128 kg each, and 96 kg each for four). A larger SUV or pickup (0.394 kg per mile) would emit about 510 kg per vehicle.

CO2 per person, Seattle 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: Seattle-Tacoma International 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.