Flights London → San Francisco — September 17, 2026

One way · Economy · 1 adult · price per person

The cheapest itinerary observed for Thursday, September 17, 2026 on the London–San Francisco route: 1 stop itinerary (2 flights) via Madrid (MAD), from London Stansted (STN) to San Francisco International (SFO), first flight Ryanair FR5996, departs 6:00 AM, arrives 4:20 PM, total travel time 18h 20m including layovers, flight time 15h 5m (layovers excluded), $423 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 10, 2026 and read by AirSource on September 10, 2026, 19:03 UTC: it is not guaranteed and is confirmed on Aviasales at booking time. The cheapest direct flight observed: United Airlines UA9099, from London Heathrow (LHR) to San Francisco International (SFO), departs 10:35 AM, arrives 1:35 PM, direct, 11h, $608 per person. Fare as listed by Aviasales: carry-on bag not included (personal item only), checked bag not included, changes not allowed, non-refundable.