United States · San Francisco
San Francisco International Airport (SFO) Online Check-in
Northern California's main airport and a major United Airlines hub. Four terminals (1, 2, 3, International) connected by AirTrain.
Now at San Francisco International Airport
- Security wait (today, avg) 18 min
- Disruption No reported disruption
- Weather impact Clear, 14 °C
Quick information
Airlines we cover at San Francisco International Airport
San Francisco International Airport hosts about 60 airlines in total. We have terminal-specific check-in pages for the 1 listed below. Pick yours to see counters, bag-drop, and online check-in details.
How to check in for a flight from San Francisco International Airport
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Check in online before you leave home
Most airlines open online check-in 24–48 hours before departure. It saves time at the airport and avoids airport-counter fees on low-cost carriers.
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Arrive at the right terminal
SFO has 4 terminal(s). Check your airline's terminal in the table above before you set off.
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Drop off checked baggage
Counters typically open 2 hours before departure and close 40 minutes before. Use self-service bag-drop kiosks to save time.
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Pass security
Liquids must be in a single transparent bag, max 100 ml each. Laptops and large electronics out of bags. Submit your security wait time below to help others.
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Reach your gate on time
Most airlines close the gate 20 minutes before departure. Allow 5–15 minutes to walk from security to the gate.
Tips for San Francisco International Airport
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BART is fastest from downtown
30 minutes from Embarcadero / Powell to SFO station, $10.85 single. AirTrain (free) connects SFO station to terminals.
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Fog delays are common
SFO has frequent low-visibility delays (especially May–August). Some flights divert to OAK or SJC. Build buffer time for connections.
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International terminal is far from domestic
International Terminal A and G are at one end; T2 and T3 at the other. AirTrain ride between can take 10+ minutes including walks.
Popular destinations from San Francisco International Airport
Frequently asked questions
Which terminal does United use at SFO?
United domestic flights use Terminal 3. United international flights (and most international Star Alliance) use the International Terminal.
How early should I arrive at SFO?
2 hours for domestic, 3 hours for international. Add 30 minutes during summer fog season (May–August) when delays propagate through the airport.
Can I get to Silicon Valley directly from SFO?
Yes — Caltrain from Millbrae station (10 min via SamTrans bus) to San Jose, Palo Alto, etc. About 30–60 minutes depending on stop.
Official sources
The check-in details on this page are sourced from each airline's website. For terminal layout, opening hours, and ground-side services, see the San Francisco International Airport official site below.
- flysfo.com — Official San Francisco International Airport website (terminal maps, parking, ground transport).
- Wikipedia: San Francisco International Airport — Editorial overview, history, statistics.
- FlightRadar24: SFO live data — Live flight arrivals, departures, and delays.
- travel.state.gov — Up-to-date entry requirements and security guidance for United States.