Flights Seattle → Boston — September 17, 2026

One way · Economy · 1 adult · price per person

The cheapest itinerary observed for Thursday, September 17, 2026 on the Seattle–Boston route: 3 stops itinerary (4 flights) via Denver International (DEN) and Calgary (YYC) and Ottawa (YOW), from Seattle-Tacoma (SEA) to Boston Logan (BOS), first flight United Airlines UA663, departs 2:34 PM, arrives 3:50 PM the next day, total travel time 22h 16m including layovers, flight time 10h 48m (layovers excluded), $262 per person. Fare as listed by Aviasales: carry-on bag not included (personal item only), checked bag not included, changes not allowed, non-refundable. Price found in an Aviasales search on September 7, 2026 and read by AirSource on September 10, 2026, 20:47 UTC: it is not guaranteed and is confirmed on Aviasales at booking time. The cheapest direct flight observed: JetBlue B6398, from Seattle-Tacoma (SEA) to Boston Logan (BOS), departs 11:42 PM, arrives 8:06 AM the next day, direct, 5h 24m, $281 per person. Fare as listed by Aviasales: carry-on bag included, checked bag not included, changes not allowed, non-refundable.