Are there nonstop flights from London (STN) to San Salvador (SAL)?

No. The fastest connection is via Madrid, about 12h 44m of total flying time.

What is the fastest connection from London (STN) to San Salvador (SAL)?

via Madrid ≈ 12h 44m, via Barcelona ≈ 13h 8m (estimated flying time, excluding layovers).

London Stansted Airport (STN) to El Salvador International Airport Saint Óscar Arnulfo Romero y Galdámez (SAL)・8,787 km

No nonstop flights. The fastest connection is via Madrid (MAD), about 12h 44m of flying time (layover not included).

None.

2 one-stop options, sorted by estimated flying time. Tap one to see the airlines on each leg and booking links.

Times are estimated from distance. Check schedules, frequency and availability with the airline or a booking site.