Is your layover long enough?

It depends on one thing above all others: whether both flights are on a single ticket. On one ticket the airline sold you the connection and owns the consequence of breaking it, so a misconnection caused by its own late inbound flight gets you rebooked at no charge, and every large US carrier has committed to exactly that in the customer service plan it filed under 14 CFR § 259.5. On two separate tickets you assembled the connection yourself, the second airline has no contract covering the first, and it is entitled to treat you as a no-show. The itinerary looks identical either way in a booking confirmation, which is why people discover the difference at the worst possible moment.

You are into the airline's discretion rather than its obligations, and it is worth knowing that the discretion is real. Most US carriers operate an informal standby or flat-fee rebooking on the next available flight for a passenger who simply did not make it, particularly where the fare class allows changes — nothing compels it, and it is applied unevenly. Two things improve your odds: going to the desk before the flight departs rather than after, because a passenger not yet recorded as a no-show is a much easier case, and asking about the next flight with seats rather than asking to be put on a specific one.

For a domestic connection within one terminal, usually yes; for anything involving a terminal change, a rail transfer or immigration, frequently not. The reason a single answer does not work is that the airport's own published minimum connection time assumes everything runs to schedule, and the number that matters is what is left after your inbound flight's typical lateness and the boarding gate closing — which is around 15 minutes before departure, not at departure. That subtraction is what the calculators on the hub pages do, using transfer times published by the airport operator rather than estimates of our own.

It is below what several of the hubs on this page can absorb, and the calculator will usually say so. Forty-five minutes leaves roughly 30 minutes of actual walking time once the gate cutoff is taken out, before your inbound flight is a minute late. That can work airside within a single concourse and does not work across a terminal change. The practical point is that a connection this tight is not merely risky but usually not your only option, and the fare difference for the next departure is smaller than the cost of the night you would spend if it fails.

Rather than a single figure, work from what has to happen in the gap: the gate cutoff first, then the transfer itself, then whatever margin your inbound flight's punctuality record justifies. A same-terminal domestic connection on a punctual route can be tight and survive. An international arrival needing immigration, baggage reclaim and a re-check needs hours rather than minutes, because none of those steps has a timetable. Each hub page here works the arithmetic with that airport's own published transfer times, and for airports where we have no sourced figure it asks you for the transfer time rather than inventing one.