Sixty minutes for a domestic connection and two hours for an international one — that is the practical buffer on a single airline ticket, and it already assumes your inbound flight is on time, per US DOT on-time statistics showing roughly one in five US flights arriving late as of 2025. Below that, you are betting against the airlines' own delay data; far above it, you are trading a whole afternoon for risk you have already covered.
This is information, not travel advice — tight connections carry real financial risk, so book the buffer your trip can afford to lose.
What is the minimum legal connection time?
Airlines file official minimum connect times (MCTs) with schedule data providers, and any connecting itinerary they sell on one ticket is, by definition, legal. Those minimums can be startlingly short — 35 to 45 minutes at some US hubs, 60 to 90 minutes for international-to-domestic arrivals that clear customs. Legal does not mean comfortable: an MCT connection assumes every flight operates flawlessly. When you choose an itinerary, look at the offered buffer and mentally add the risk premium yourself; if the booking tool shows 40 minutes at a huge airport, treat it as a same-day gamble, not a plan.
How much buffer for a domestic connection?
Sixty minutes is the sensible floor on a single ticket at a mid-size hub; 90 minutes is the comfortable choice at large, spread-out airports — think multiple terminals, long taxi times, or a terminal change. Two structural risks dominate: late arrivals, which DOT data puts at roughly 20 percent for US carriers as of 2025, and slow ground movements at big hubs where deplaning and a gate change alone can eat 30 minutes. If you check a bag, the airline's re-check tolerance on a missed connection is on the clock too.
Checked bags tighten every one of these numbers. On a same-airline connection your bags are transferred automatically, but the loading crew needs the same buffer you do — a 50-minute gap where you sprint and make the gate is a gap your suitcase frequently loses. If the itinerary is marginal and you can travel carry-on only, do it; a traveler without checked luggage can accept a checked-bag traveler should not.
How much for an international connection?
Two hours, minimum, when you arrive from abroad on a single ticket. The first step after landing is passport control, which can take anywhere from 10 minutes to over an hour at peak arrivals banks; bags must be collected and re-checked at many gateways; and security re-entry follows. Government checkpoint wait data and airport-specific arrival patterns both argue for the full two hours at US gateways and at busy European or Asian hubs. For connections that stay airside — say, Frankfurt to a non-Schengen destination — 90 minutes is generally workable on one ticket, because you skip immigration and bag claim entirely.
Related stories: Open-Jaw and Multi-City Tickets: How to Book a Two-Country Trip Right · When to Book Flights: What the Booking-Window Data Actually Shows.
What about separate tickets and self-transfers?
This is where the rules change completely. On two separate tickets, no airline owes you anything if the first flight is late: the second carrier can rebook you at its lowest availability, in the worst case for a same-day fare, and your checked bags stay with the first airline. Travelers who deliberately combine two tickets — the self-transfer strategy — should budget at least four to six hours for a domestic-to-domestic pair and consider an overnight for anything involving customs, or baggage re-check. Some search tools now sell virtual interlining combinations on one booking; read the fine print, because the protection still depends on who issued the ticket.
What happens if you miss the connection on one ticket?
On a single ticket, the airline rebooks you on its next available service at no charge — that is the contract you bought. US carriers' customer service plans commit to rebooking on the same or partner airline; under DOT's automatic refund rules, a cancelled itinerary you choose not to take gets a cash refund. In the EU, departing from an EU airport adds Regulation 261/2004: long delays on arrival can trigger compensation of 250 to 600 euros depending on distance. None of this covers the meeting you missed — which is the real reason the buffer matters more than the fare.
Quick buffer guide
| Connection type | Sensible buffer | Why |
|---|---|---|
| Domestic, same terminal, one ticket | 60 min | Covers a routine late arrival |
| Domestic, terminal change, big hub | 90 min | Train or walk between terminals adds 20-30 min |
| International arrival, single ticket | 120 min | Immigration, bags, customs, security |
| Airside international connection | 90 min | No immigration; gate distance is the risk |
| Two separate tickets | 4-6 hrs or overnight | No rebooking protection |
Buffers above are planning guidance checked as of early 2026 against DOT on-time statistics and airline MCT practice; specific airports and airlines vary, so verify your exact itinerary before booking.