Atlanta to Denver

Between Atlanta and Denver, 1.7 million passengers flew nonstop in 2025, on 11 thousand flights of about 1,199 miles and 2.6 hours in the air. The average passenger accounted for about 165 kg of CO2 from the fuel burned, from 123 kg on Frontier Airlines to 196 kg on United Airlines.

165 kgCO2 per passenger, average
1,199 milesabout 2.6 hours in the air
1.7 millionpassengers in 2025
86%of seats filled

CO2 per passenger, airline by airline

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

Atlanta to Denver by airline, 2025

Airline	Share of passengers	Flights (thousands)	Main aircraft	Seats per flight	Seats filled	kg CO2 per passenger
Delta Air Lines	53%	5.4	Airbus A321, Boeing 757-200	190	88%	167
Southwest Airlines	18%	2.2	Boeing 737 MAX 8, Boeing 737-800	165	83%	160
United Airlines	16%	2.1	Airbus A319, Airbus A320-200	148	84%	196
Frontier Airlines	13%	1.3	Airbus A320neo, Airbus A321neo	202	88%	123

What explains the differences

It's number 90 of the 100 busiest city pairs by passengers, and number 25 for the lowest CO2 per mile flown (0.14 kg per passenger-mile, number 1 being the lowest). A typical route of 1,199 miles in this set comes out at about 176 kg, so this one is 6.5% below it.

The airlines on this route differ by 59% per passenger. Frontier Airlines burned 2,238 gallons per flight and 177 passengers on each, and United Airlines 2,479 gallons and 123 passengers. Fuel burned per flight explains about 22% of the gap and the number of passengers on each flight the other 78%. Frontier Airlines flew 88% full here against 84% for United Airlines, flying mostly Airbus A320neo against Airbus A319.

For comparison, the EPA default factor for a flight of this length (0.129 kg per passenger-mile) would give 155 kg. The EPA figure is a national average for flights of that length. The measured figure for this route is 6.4% higher.

2019 compared with 2025

In 2019 the route carried 1.7 million passengers on 12 thousand flights. In 2025 it carried 1.7 million, down 3%, on 11 thousand flights, down 10%. The average flight had 160 seats then and 178 now, and 89% of them were filled against 86%.

CO2 per passenger was 163 kg in 2019 and 165 kg in 2025, up 1.0%. Fuel burned per flight was up 9.0% (2,378 gallons to 2,593) and passengers per flight were up 7.9% (142 to 154). The distance flown was about the same (1,199 miles then, 1,199 now).

Delta Air Lines led in both years, with 52% of passengers in 2019 and 53% in 2025. United Airlines gained the most share, 10% to 16%. Southwest Airlines lost the most, 22% to 18%. Republic Airways and Spirit Airlines no longer reach 1% of passengers, having had 4% in 2019.

Airline by airline, Frontier Airlines went from 130 kg to 123 kg per passenger (193 seats per flight to 202, main aircraft Airbus A320neo in both years); Delta Air Lines went from 153 kg to 167 kg per passenger (180 seats per flight to 190, main aircraft Boeing 737-900ER then and Airbus A321 now).

Atlanta to Denver, 2019 and 2025

Measure	2019	2025
Passengers (thousands)	1,743	1,692
Flights (thousands)	12.2	11.0
Seats filled	89%	86%
Gallons of fuel per flight	2,378	2,593
kg CO2 per passenger	163	165

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.

Atlanta to Denver and back: time in the air

Flights from Atlanta to Denver spent 172 minutes in the air on average in 2025, against 144 minutes from Denver to Atlanta: 28 minutes longer, 19% 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 985 gallons per flight hour, those extra minutes cost about 458 gallons per flight, which is about 3.0 gallons or 29 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
Atlanta to Denver	171.9	5,507
Denver to Atlanta	144.0	5,503

Fly or drive

Driving is about 1,403 miles by road, which we estimate as 1.17 times the straight-line distance. An average car emits about 417 kg of CO2 on the trip, at the EPA figure of 0.297 kg per vehicle-mile. Alone, that's 153% more than the 165 kg for a passenger on the flight.

With 3 people in the car, driving comes out lower per person than the flight (139 kg each, and 104 kg each for four). A larger SUV or pickup (0.394 kg per mile) would emit about 553 kg per vehicle.

CO2 per person, Atlanta to Denver. 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: Denver International Airport, Hartsfield-Jackson Atlanta 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.