Boston (BOS) to Seattle (SEA)
Flight time
≈ 5h 47m
Bearing
296° NW
Boston (BOS) to Seattle (SEA) is 2,489 miles (4,006 km) as the crow flies — the great-circle baseline most distance-based mileage programs credit.
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What actually flies BOS–SEA
Filed traffic dataIn May 2026, Alaska Airlines operated the most departures, one of 3 carriers flying nonstop BOS–SEA; the Airbus A321neo was the most common aircraft at 44% of departures; flights ran 86% full.
Departures
506
May 2026
Seats
94,217
both directions
Passengers
81,086
both directions
Load factor
86.1%
RPM ÷ ASM
Who flies BOS–SEA?
Alaska Airlines operated the most nonstop BOS–SEA departures in May 2026 (248), one of 3 carriers on the route.
- AS
248 departures · 43,974 seats
Share of departures49.0%86.4%
Load
- DL
222 departures · 43,043 seats
Share of departures43.9%85.9%
Load
- B6
36 departures · 7,200 seats
Share of departures7.1%84.7%
Load
What plane flies BOS–SEA?
In May 2026, the Airbus A321neo flew 44% of BOS–SEA departures — more than any other aircraft type.
- Airbus A321neo
221 departures · 85.9% load
43.7% - Boeing 737-900ER
125 departures · 86.1% load
24.7% - Boeing 737 MAX 9
114 departures · 86.8% load
22.5% - Airbus A321
36 departures · 84.7% load
7.1% - Boeing 737-800
9 departures · 87.2% load
1.8% - Boeing 737 MAX 8
1 departures · 90.1% load
0.2%
How has BOS–SEA traffic changed?
Nonstop BOS–SEA departures fell from 508 in June 2025 to 506 in May 2026.
Monthly nonstop BOS–SEA traffic, trailing 12 months through May 2026. Bars scale to the busiest month; months with no filed service show as zero.
June 2025
508 departures · 85,201 passengers
89.8%
Load
July 2025
538 departures · 93,292 passengers
93.2%
Load
August 2025
539 departures · 94,917 passengers
93.8%
Load
September 2025
457 departures · 75,779 passengers
89.2%
Load
October 2025
451 departures · 72,454 passengers
86.4%
Load
November 2025
320 departures · 48,160 passengers
81.5%
Load
December 2025
315 departures · 47,989 passengers
83.2%
Load
January 2026
245 departures · 36,984 passengers
81.8%
Load
February 2026
242 departures · 35,464 passengers
79.4%
Load
March 2026
341 departures · 52,934 passengers
83.9%
Load
April 2026
342 departures · 53,611 passengers
84.5%
Load
May 2026
506 departures · 81,086 passengers
86.1%
Load
By direction
Each direction is filed separately — they rarely match.
BOS → SEA
87.5% full
253 departures · 41,217 passengers
SEA → BOS
84.7% full
253 departures · 39,869 passengers
Nonstop BOS–SEA traffic has been filed since 2025.
Source: US DOT BTS Form 41 T-100 Segment (All Carriers). Data through May 2026; filings from 2025. Public domain (US Government work).
The airports
Frequently asked
How far is Boston (BOS) from Seattle (SEA)?
BOS to SEA is 2,489 miles (4,006 km / 2,163 nautical miles) measured great-circle — the shortest path over the surface of the Earth.
How long is the flight from BOS to SEA?
A nonstop covers the 2,489-mile great-circle distance in roughly 5h 47m of block time, before winds. Actual schedules vary a few percent by direction and aircraft.
What plane flies BOS–SEA?
In May 2026, the Airbus A321neo flew the largest share of departures (43.7%), followed by the Boeing 737-900ER (24.7%).
What mileage do I earn flying BOS–SEA?
Distance-based programs credit off the 2,489-mile great-circle figure, then apply your fare-class earning rate. Revenue-based programs credit off the fare instead.
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