The cheapest round-trip from Porto to San Francisco is about 665 EUR, usually in September 2026; August 2026 is priciest, so booking the low month saves around 14 EUR (~2%). Typical fare ~665 EUR, from 91 priced fares. Flightmussy live data, updated 2026-06-05.
Cheap flights from Porto (OPO) to San Francisco (SFO/OAK/SJC). Free, no signup, no ads, no tracking. Compare every airline across 12 months of fares on one heatmap — including low-cost carriers Google Flights often deprioritises.
Cheapest round-trip seen: 665 EUR, usually around September 2026. Typical fare ~665 EUR. Across the year prices range roughly 665–679 EUR — about 2% cheaper in the low season than the peak (August 2026). Carriers on this route include American, KLM, Air France, Delta.
Based on Flightmussy's live 12-month fare data; prices last updated 2026-06-05. Prices change constantly — search live for current fares.
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