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Rankings / Routes / Washington, DC to Houston

2025 flights

Washington, DC to Houston

Between Washington, DC and Houston, 2.0 million passengers flew nonstop in 2025, on 17 thousand flights of about 1,216 miles and 2.7 hours in the air. The average passenger accounted for about 193 kg of CO2 from the fuel burned, from 144 kg on Spirit Airlines to 201 kg on United Airlines.

  • 193 kgCO2 per passenger, average
  • 1,216 milesabout 2.7 hours in the air
  • 2.0 millionpassengers in 2025
  • 79%of seats filled

CO2 per passenger, airline by airline

CO2 per passenger by airline, Washington, DC to HoustonBar chart of kilograms of CO2 per passenger on each airline between Washington, DC and Houston in 2025.050100150200Spirit Airlines144 kgSouthwest Airlines180 kgUnited Airlines201 kg
CO2 per passenger by airline, Washington, DC to HoustonBar chart of kilograms of CO2 per passenger on each airline between Washington, DC and Houston in 2025.0100200Spirit Airlines144 kgSouthwest Airlines180 kgUnited Airlines201 kg
Kilograms of CO2 per passenger, one way, 2025. Fuel burned only. Less is better.
Washington, DC to Houston by airline, 2025
AirlineShare of passengersFlights (thousands)Main aircraftSeats per flightSeats filledkg CO2 per passenger
United Airlines58%9.9Boeing 737-800, Boeing 737-70015479%201
Southwest Airlines31%5.0Boeing 737-700, Boeing 737 MAX 816278%180
Spirit Airlines8%0.9Airbus A320neo, Airbus A321neo20283%144

What explains the differences

It's number 65 of the 100 busiest city pairs by passengers, and number 57 for the lowest CO2 per mile flown (0.16 kg per passenger-mile, number 1 being the lowest). A typical route of 1,216 miles in this set comes out at about 178 kg, so this one is 8.4% above it.

The flights use more than one pair of airports: IAD to IAH (26%), DCA to IAH (26%), BWI to HOU (20%). The figures here cover all of them.

The airlines on this route differ by 40% per passenger. Spirit Airlines burned 2,463 gallons per flight and 167 passengers on each, and United Airlines 2,484 gallons and 121 passengers. Fuel burned per flight explains about 3% of the gap and the number of passengers on each flight the other 97%. Spirit Airlines flew 83% full here against 79% for United 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 157 kg. The EPA figure is a national average for flights of that length. The measured figure for this route is 23% higher.

2019 compared with 2025

In 2019 the route carried 1.9 million passengers on 16 thousand flights. In 2025 it carried 2.0 million, up 8%, on 17 thousand flights, up 6%. The average flight had 142 seats then and 154 now, and 84% of them were filled against 79%.

CO2 per passenger was 196 kg in 2019 and 193 kg in 2025, down 1.5%. Fuel burned per flight was down 0.2% (2,393 gallons to 2,389) and passengers per flight were up 1.4% (119 to 121). The distance flown was about the same (1,216 miles then, 1,216 now).

United Airlines led in both years, with 48% of passengers in 2019 and 58% in 2025. Southwest Airlines lost the most, 34% to 31%. Mesa Airlines and Republic Airways no longer reach 1% of passengers, having had 11% in 2019.

Airline by airline, Spirit Airlines went from 151 kg to 144 kg per passenger (178 seats per flight to 202, main aircraft Airbus A320-200 then and Airbus A320neo now); United Airlines went from 200 kg to 201 kg per passenger (159 seats per flight to 154, main aircraft Airbus A320-200 then and Boeing 737-800 now).

Washington, DC to Houston, 2019 and 2025
Measure20192025
Passengers (thousands)1,8982,042
Flights (thousands)15.916.9
Seats filled84%79%
Gallons of fuel per flight2,3932,389
kg CO2 per passenger196193
CO2 per passenger by airline, 2019 and 2025, Washington, DC to HoustonBar chart of kilograms of CO2 per passenger on Washington, DC to Houston for each major airline in 2019 and in 2025.050100150200United Airlines 2019200 kgUnited Airlines 2025201 kgSouthwest Airlines 2019182 kgSouthwest Airlines 2025180 kgSpirit Airlines 2019151 kgSpirit Airlines 2025144 kg
CO2 per passenger by airline, 2019 and 2025, Washington, DC to HoustonBar chart of kilograms of CO2 per passenger on Washington, DC to Houston for each major airline in 2019 and in 2025.0100200United Airlines 2019200 kgUnited Airlines 2025201 kgSouthwest Airlines 2019182 kgSouthwest Airlines 2025180 kgSpirit Airlines 2019151 kgSpirit Airlines 2025144 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.

Washington, DC to Houston and back: time in the air

Flights from Washington, DC to Houston spent 173 minutes in the air on average in 2025, against 152 minutes from Houston to Washington, DC: 21 minutes longer, 14% 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 881 gallons per flight hour, those extra minutes cost about 313 gallons per flight, which is about 2.6 gallons or 25 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
Washington, DC to Houston173.38,437
Houston to Washington, DC152.08,472

Fly or drive

Driving is about 1,423 miles by road, which we estimate as 1.17 times the straight-line distance. An average car emits about 423 kg of CO2 on the trip, at the EPA figure of 0.297 kg per vehicle-mile. Alone, that's 119% more than the 193 kg for a passenger on the flight.

With 3 people in the car, driving comes out lower per person than the flight (141 kg each, and 106 kg each for four). A larger SUV or pickup (0.394 kg per mile) would emit about 561 kg per vehicle.

CO2 per person by way of travel, Washington, DC to HoustonBar chart of kilograms of CO2 per person flying, driving or taking the train between Washington, DC and Houston.0100200300400Flight, average193 kgCar, driver alone423 kgCar, 2 people211 kgCar, 4 people106 kg
CO2 per person by way of travel, Washington, DC to HoustonBar chart of kilograms of CO2 per person flying, driving or taking the train between Washington, DC and Houston.0200400Flight, average193 kgCar, driver alone423 kgCar, 2 people211 kgCar, 4 people106 kg
CO2 per person, Washington, DC to Houston. 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

Washington, DC to Boston100 kg CO2 per passenger over 383 milesAtlanta to Washington, DC104 kg CO2 per passenger over 554 milesMiami to Washington, DC144 kg CO2 per passenger over 921 milesChicago to Washington, DC121 kg CO2 per passenger over 609 milesLos Angeles to Seattle151 kg CO2 per passenger over 959 milesChicago to Dallas-Fort Worth126 kg CO2 per passenger over 800 milesDallas-Fort Worth to Denver102 kg CO2 per passenger over 644 milesNew York to San Francisco414 kg CO2 per passenger over 2,578 miles

Airports on this route: Washington Dulles International Airport, George Bush Intercontinental Airport, Ronald Reagan Washington National Airport, Baltimore/Washington International Thurgood Marshall Airport, William P. Hobby 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.