For SFO, a good rule is 2 hours before domestic flights and 3 hours before international flights. If you’re checking bags, traveling at peak times, or want extra cushion, add 30 minutes.

Practical timing

  • Domestic, normal hours: arrive 2 hours early.
  • Domestic, peak times or holidays: arrive 2 hours 30 minutes early.
  • International: arrive 3 hours early.
  • International, busy periods: arrive 3 hours 30 minutes early.
  • With TSA PreCheck and no checked bags, some travelers do fine with about 1 hour 30 minutes for domestic flights.

Why the buffer matters

SFO can move quickly, but check-in, bag drop, security, AirTrain transfers, and gate changes can still eat time. Peak morning and late-afternoon periods are the riskiest for delays, so the safer plan is to arrive earlier than you think you need.

Simple rule

If you want one number to remember:

  • Domestic: 2 hours
  • International: 3 hours

For a tight schedule, tell me whether your flight is domestic or international, and whether you’re checking bags or using PreCheck.