How long a layover do I need to make an international flight?

More than enough time as long as the first flight to Logan is not delayed by 4hours

As with most answers to most questions..."it depends."

You're on one ticket, right? (If not, it's a whole 'nother different calculation).

What time of year? (They do get weather in Boston, winter snowstorms can throw a wrench in any plans).

In most cases, 6 hours should be more than plenty of time to connect there.

Thank you, David, for the useful post. Yes, same ticket, same airline. Leaving early October; returning early November.

Logan isn't that big so 6hrs is plenty.

Is a 1:43 layover at Hartsfield–Jackson Atlanta enough time to make a Delta flight to Heathrow? It's all on the same ticket.

Is a 1:43 layover at Hartsfield–Jackson Atlanta enough time to make a Delta flight to Heathrow?

As we say, depends. The incoming flight might be quite late. Do you go through security from domestic to international? That could be bad. How far is the walk from luggage carousel back to international? The outbound flight is not likely to leave early but it might be late.

Thank you for the reply. My understanding is that, in Atlanta, one doesn't have to go through security again for a domestic to international flight. Also, I won't be checking luggage. Backpack only, and I'm sitting near the front of the plane (both flights).

There is an earlier domestic flight in to take the same international flight. This would give me a 3:48 layover.

@pollyannapax, no, you shouldn't have to go through security. It's probably enough time but as bogiesan said, if your incoming flight is delayed, all bets are off. If it were me, I'd probably take the earlier flight - if the flight is on time, then just grab a cup of coffee and a bite to eat while you wait.

Good advice, I appreciate it. The last time I flew international was over 40 years ago, so I'm a bit rusty.

The last time I flew international was over 40 years ago, so I'm a bit rusty.

Take an earlier flight, under 2 hours is cutting it too short, you will not regret it. No need to get screwed up by a late connection, or worse a cancellation, for this special trip...that day is already committed to getting you to London, starting the day a little earlier is no big deal. We always get to the international gateway airport with the earliest possible flight connection of the day from our regional airport.

Flight changed. I now have a 3:48 layover. Thanks to everyone for your advice!