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Rankings / Routes / Chicago to Phoenix

2025 flights

Chicago to Phoenix

Between Chicago and Phoenix, 2.4 million passengers flew nonstop in 2025, on 17 thousand flights of about 1,441 miles and 3.1 hours in the air. The average passenger accounted for about 190 kg of CO2 from the fuel burned, from 155 kg on Frontier Airlines to 199 kg on American Airlines.

  • 190 kgCO2 per passenger, average
  • 1,441 milesabout 3.1 hours in the air
  • 2.4 millionpassengers in 2025
  • 83%of seats filled

CO2 per passenger, airline by airline

CO2 per passenger by airline, Chicago to PhoenixBar chart of kilograms of CO2 per passenger on each airline between Chicago and Phoenix in 2025.050100150200Frontier Airlines155 kgSouthwest Airlines185 kgUnited Airlines189 kgAmerican Airlines199 kg
CO2 per passenger by airline, Chicago to PhoenixBar chart of kilograms of CO2 per passenger on each airline between Chicago and Phoenix in 2025.0100200Frontier Airlines155 kgSouthwest Airlines185 kgUnited Airlines189 kgAmerican Airlines199 kg
Kilograms of CO2 per passenger, one way, 2025. Fuel burned only. Less is better.
Chicago to Phoenix by airline, 2025
AirlineShare of passengersFlights (thousands)Main aircraftSeats per flightSeats filledkg CO2 per passenger
American Airlines36%5.8Boeing 737-800, Airbus A32117885%199
Southwest Airlines34%6.1Boeing 737 MAX 8, Boeing 737-80016882%185
United Airlines24%3.9Boeing 737-900ER, Airbus A321neo18481%189
Frontier Airlines5%0.8Airbus A320neo, Airbus A321neo20283%155

What explains the differences

It's number 46 of the 100 busiest city pairs by passengers, and number 15 for the lowest CO2 per mile flown (0.13 kg per passenger-mile, number 1 being the lowest). A typical route of 1,441 miles in this set comes out at about 206 kg, so this one is 7.8% below it.

The flights use more than one pair of airports: PHX to ORD (68%), PHX to MDW (32%). The figures here cover all of them.

The airlines on this route differ by 29% per passenger. Frontier Airlines burned 2,660 gallons per flight and 168 passengers on each, and American Airlines 3,097 gallons and 152 passengers. Fuel burned per flight explains about 60% of the gap and the number of passengers on each flight the other 40%. Frontier Airlines flew 83% full here against 85% for American Airlines, flying mostly Airbus A320neo against Boeing 737-800.

For comparison, the EPA default factor for a flight of this length (0.129 kg per passenger-mile) would give 186 kg. The EPA figure is a national average for flights of that length. The measured figure for this route is 2.0% higher.

2019 compared with 2025

In 2019 the route carried 2.4 million passengers on 15 thousand flights. In 2025 it carried 2.4 million, up 1%, on 17 thousand flights, up 9%. The average flight had 173 seats then and 177 now, and 91% of them were filled against 83%.

CO2 per passenger was 190 kg in 2019 and 190 kg in 2025, unchanged. Fuel burned per flight was down 7.0% (3,063 gallons to 2,848) and passengers per flight were down 6.8% (157 to 146). The distance flown was about the same (1,441 miles then, 1,441 now).

American Airlines led in both years, with 42% of passengers in 2019 and 36% in 2025. Southwest Airlines gained the most share, 29% to 34%. American Airlines lost the most, 42% to 36%. Spirit Airlines no longer reaches 1% of passengers, having had 2% in 2019.

Airline by airline, United Airlines went from 198 kg to 189 kg per passenger (165 seats per flight to 184, main aircraft Boeing 737-900ER in both years); Southwest Airlines went from 178 kg to 185 kg per passenger (163 seats per flight to 168, main aircraft Boeing 737-800 then and Boeing 737 MAX 8 now).

Chicago to Phoenix, 2019 and 2025
Measure20192025
Passengers (thousands)2,4002,432
Flights (thousands)15.316.6
Seats filled91%83%
Gallons of fuel per flight3,0632,848
kg CO2 per passenger190190
CO2 per passenger by airline, 2019 and 2025, Chicago to PhoenixBar chart of kilograms of CO2 per passenger on Chicago to Phoenix for each major airline in 2019 and in 2025.050100150200American Airlines 2019199 kgAmerican Airlines 2025199 kgSouthwest Airlines 2019178 kgSouthwest Airlines 2025185 kgUnited Airlines 2019198 kgUnited Airlines 2025189 kgFrontier Airlines 2019150 kgFrontier Airlines 2025155 kg
CO2 per passenger by airline, 2019 and 2025, Chicago to PhoenixBar chart of kilograms of CO2 per passenger on Chicago to Phoenix for each major airline in 2019 and in 2025.0100200American Airlines 2019199 kgAmerican Airlines 2025199 kgSouthwest Airlines 2019178 kgSouthwest Airlines 2025185 kgUnited Airlines 2019198 kgUnited Airlines 2025189 kgFrontier Airlines 2019150 kgFrontier Airlines 2025155 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.

Chicago to Phoenix and back: time in the air

Flights from Chicago to Phoenix spent 199 minutes in the air on average in 2025, against 173 minutes from Phoenix to Chicago: 25 minutes longer, 15% 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 920 gallons per flight hour, those extra minutes cost about 389 gallons per flight, which is about 2.7 gallons or 26 kg of CO2 for each passenger on the slower direction. The route figure above averages both directions.

Time in the air by direction, 2025
DirectionAverage minutes in the airFlights
Chicago to Phoenix198.58,303
Phoenix to Chicago173.18,298

Fly or drive

Driving is about 1,686 miles by road, which we estimate as 1.17 times the straight-line distance. An average car emits about 501 kg of CO2 on the trip, at the EPA figure of 0.297 kg per vehicle-mile. Alone, that's 164% more than the 190 kg for a passenger on the flight.

With 3 people in the car, driving comes out lower per person than the flight (167 kg each, and 125 kg each for four). A larger SUV or pickup (0.394 kg per mile) would emit about 664 kg per vehicle.

CO2 per person by way of travel, Chicago to PhoenixBar chart of kilograms of CO2 per person flying, driving or taking the train between Chicago and Phoenix.0200400Flight, average190 kgCar, driver alone501 kgCar, 2 people250 kgCar, 4 people125 kg
CO2 per person by way of travel, Chicago to PhoenixBar chart of kilograms of CO2 per person flying, driving or taking the train between Chicago and Phoenix.0200400Flight, average190 kgCar, driver alone501 kgCar, 2 people250 kgCar, 4 people125 kg
CO2 per person, Chicago 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

New York to Chicago125 kg CO2 per passenger over 730 milesLos Angeles to Phoenix74 kg CO2 per passenger over 354 milesLos Angeles to Chicago225 kg CO2 per passenger over 1,739 milesChicago to Washington, DC121 kg CO2 per passenger over 609 milesDenver to Washington, DC192 kg CO2 per passenger over 1,471 milesAtlanta to Las Vegas229 kg CO2 per passenger over 1,747 milesDenver to Seattle135 kg CO2 per passenger over 1,024 milesNew York to Denver213 kg CO2 per passenger over 1,616 miles

Airports on this route: O'Hare International Airport, Midway 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.