Miami to Boston

Between Miami and Boston, 2.2 million passengers flew nonstop in 2025, on 16 thousand flights of about 1,244 miles and 2.9 hours in the air. The average passenger accounted for about 186 kg of CO2 from the fuel burned, from 150 kg on Spirit Airlines to 211 kg on Delta Air Lines.

186 kgCO2 per passenger, average
1,244 milesabout 2.9 hours in the air
2.2 millionpassengers in 2025
84%of seats filled

CO2 per passenger, airline by airline

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

Miami to Boston by airline, 2025

Airline	Share of passengers	Flights (thousands)	Main aircraft	Seats per flight	Seats filled	kg CO2 per passenger
JetBlue	34%	5.7	Airbus A320-200, Airbus A220-300	159	83%	198
American Airlines	31%	4.4	Boeing 737-800, Airbus A321neo	179	88%	172
Delta Air Lines	19%	3.2	Boeing 737-800, Airbus A321	165	79%	211
Spirit Airlines	14%	2.0	Airbus A320neo, Airbus A320-200	193	85%	150

What explains the differences

It's number 57 of the 100 busiest city pairs by passengers, and number 47 for the lowest CO2 per mile flown (0.15 kg per passenger-mile, number 1 being the lowest). A typical route of 1,244 miles in this set comes out at about 181 kg, so this one is close to that.

The flights use more than one pair of airports: BOS to MIA (48%), BOS to FLL (44%), PVD to FLL (7%). The figures here cover all of them.

The airlines on this route differ by 40% per passenger. Spirit Airlines burned 2,521 gallons per flight and 164 passengers on each, and Delta Air Lines 2,818 gallons and 130 passengers. Fuel burned per flight explains about 33% of the gap and the number of passengers on each flight the other 67%. Spirit Airlines flew 85% full here against 79% for Delta Air Lines, 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 160 kg. The EPA figure is a national average for flights of that length. The measured figure for this route is 16% higher.

2019 compared with 2025

In 2019 the route carried 1.8 million passengers on 12 thousand flights. In 2025 it carried 2.2 million, up 25%, on 16 thousand flights, up 25%. The average flight had 163 seats then and 171 now, and 88% of them were filled against 84%.

CO2 per passenger was 184 kg in 2019 and 186 kg in 2025, up 0.6%. Fuel burned per flight was up 0.4% (2,707 gallons to 2,718) and passengers per flight were down 0.2% (143 to 143). The distance flown was about the same (1,238 miles then, 1,244 now).

American Airlines had the most passengers in 2019 (38%) and JetBlue in 2025 (34%). Delta Air Lines gained the most share, 7% to 19%. American Airlines lost the most, 38% to 31%. Southwest Airlines no longer reaches 1% of passengers, having had 7% in 2019.

Airline by airline, American Airlines went from 184 kg to 172 kg per passenger (167 seats per flight to 179, main aircraft Boeing 737-800 in both years); Delta Air Lines went from 193 kg to 211 kg per passenger (163 seats per flight to 165, main aircraft Airbus A320-200 then and Boeing 737-800 now).

The airports changed too: BOS to MIA handled 38% of the passengers in 2019 and 48% in 2025.

Miami to Boston, 2019 and 2025

Measure	2019	2025
Passengers (thousands)	1,772	2,215
Flights (thousands)	12.4	15.5
Seats filled	88%	84%
Gallons of fuel per flight	2,707	2,718
kg CO2 per passenger	184	186

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.

Miami to Boston and back: time in the air

Flights from Boston to Miami spent 178 minutes in the air on average in 2025, against 164 minutes from Miami to Boston: 14 minutes longer, 9% 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 954 gallons per flight hour, those extra minutes cost about 229 gallons per flight, which is about 1.6 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
Boston to Miami	178.2	7,751
Miami to Boston	163.8	7,753

Fly or drive

Driving is about 1,455 miles by road, which we estimate as 1.17 times the straight-line distance. An average car emits about 432 kg of CO2 on the trip, at the EPA figure of 0.297 kg per vehicle-mile. Alone, that's 133% more than the 186 kg for a passenger on the flight.

With 3 people in the car, driving comes out lower per person than the flight (144 kg each, and 108 kg each for four). A larger SUV or pickup (0.394 kg per mile) would emit about 573 kg per vehicle.

CO2 per person, Miami to Boston. 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: Miami International Airport, Fort Lauderdale-Hollywood.

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.