When to leave for SFO.

Every row is editable: tap the boarding time or any duration and the whole plan recomputes backward. The first travel row — drive, ride, or train — is your leave-by time; the top row is when the trip actually starts.

The 30-minute drive is a typical run from San Francisco without traffic. Check the real drive to SFO at the hour you’ll actually leave, then put that number in.

Getting to San Francisco International

BART runs directly into the International Terminal and the AirTrain loops every terminal and the long-term lots from there, so transit is a genuinely competitive option. Long-term parking means the AirTrain ride is its own step, not a rounding error.

The moving targets — today’s security waits, parking availability, terminal maps — live on the official SFO site. This page covers the part that doesn’t change: the backward arithmetic from boarding.

The part the airport can't see

Every airport tells you when to arrive. None of them tell you when to get in the shower, and that's the number that decides whether the morning is calm or a scramble. The plan above keeps subtracting past the drive — through packing, through getting ready — until it lands on a start time you can actually act on.

That's what Ready Time does for the whole trip: set boarding as the deadline, list the real steps, and get an alert when each one is due to start. It can even pick the flight up from your calendar.

How early should I get to SFO?

Two hours before a domestic departure is the sensible default, three for international. Shave it only on routes and hours you know firsthand. US-101 through the city and down the Peninsula is the swing variable: 25 minutes midday is 50 in the commute crush.

How long is security at SFO?

Checkpoints are per-terminal and generally well run; the International Terminal's gates sprawl, so the walk after security can be the longest leg. Summer fog is SFO's signature schedule risk — morning departures get delayed more often than you'd guess, which argues for not cutting the connection thin rather than arriving later. Whatever wait you've heard about, treat the 25-minute security row in the plan above as a default to edit, not a promise: TSA PreCheck reliably shrinks it, and a checked bag reliably grows the step before it.

Does flying international out of SFO change this?

Mostly at the front of the chain. International check-in usually means the airline desk rather than a kiosk — documents get checked, and counters often close an hour before departure — and boarding opens earlier relative to takeoff. Choose “check-in desk” above the plan, give that row room, and take the boarding time from your boarding pass instead of guessing backward from departure. The same choice covers anyone the kiosk can't help: lap infants, unaccompanied minors, oversized bags.

When should I leave for SFO?

Work backward from boarding, in order: time at the gate, the walk, security, bag drop, parking, then the drive — 30 minutes in the default plan, which you should replace with your route at the hour you'll actually drive it. The calculator above runs the subtraction; the leave-by moment is the first travel row — "Drive to SFO" in the default plan.

Can I get an alert when it's time to leave?

That's Ready Time's whole job. Build this plan once in the app and every step gets its own notification at its start time — start packing, leave now, you're at security's mercy from here. It can detect flights from your calendar, and the alerts carry the countdown to boarding.

Not flying? The generic leave time calculator does the same math for any appointment, and the wake-up time calculator runs it all the way back to the alarm.