Connecting flight in Paris from USA - do I need to go through custom?

Yes, on arrival you must go through Passport Control and security before going to your connecting gate. Presumably this is on a single ticket? If so, you should have your boarding passes for the connecting flight.

This link provides more info: https://easycdg.com/passenger-information/transit-connecting-flight-connections-paris-cdg-airport/

No, you will got through customs when you have access to your bags in Italy. Carry on makes no difference. You will go through immigration (passport control) since Paris is your stop. Assume your connect is a part of your original ticket.

An hour is quite tight. The airline will say this is a “legal” connection time but I would start looking at what flights to Florence are leaving later in case you need to re-book. Use the bathroom on the airplane before you land. Check your connecting flight as soon as you de-plane. The signs will direct you. You stay airside but because you are flying from the US (a non-Schengen country) you pass through passport control and security in CDG. Depending on how many planes have landed about the time yours does, the staffing at passport control, how long it takes you to de-plane, how far your next gate is-all these will determine whether or not you make your connection. Customs will be in Florence and you just get in the nothing to declare line and walk through.

I agree this is a tight connection. If your flight from Detroit is early you might make it. I landed on a Delta flight from Seattle and transited to a flight to Milan in 2022. I timed myself because a friend had a short transit time. It took me 1h5m from the time I stepped off the plane to get to my gate.

You will follow the “Correspondence“ signs to 2F. You will go thru Security and passport control once you get to 2F.

The good thing is there are probably flights to Florence every 2 hours or so and they’ll book you on the next one with available seats.

Immigration/Passport Control is for people. Customs is for your stuff. Two separate things.

You always go through passport control at your first entry into Schengen. Customs, however, is done at your final stop.

If this is one ticket, meaning you bought it as one, and you miss the connection, the airline will put you on the next available flight at no charge to you.

I often go to FLR via Paris CDG (with Air France). If you can make it in one hour chapeau to you. I’ll take my hat off, because that will be impressive. Make sure you wear running shoes, and also put plenty of grease on your carryon wheels because they’ll be rolling really fast. 90 minutes is the minimum I want for Paris CDG, 2 hours even better.

I flew through CDG twice earlier this year, both times it took about 1 hour to get from the plane to the next gate. I hope you get into CDG early enough (hopefully the morning) so you can get on another flight the same day in case you miss it.

Both times I had to take the bus between Terminal G and Terminal E.

If you are unfamiliar with CDG, then I highly doubt you will make a connection in one hour.

I recently transited CDG in one hour and to do this I had to run through two terminals and jump ahead of about 50 people in the immigration line (with permission). I also speak French, which helped. I was pushy, sweaty and nearly in tears trying to get to my next plane (my mom was having heart surgery and I needed to make the flight). I made it with two minutes to spare, with the gate agents waving me in and telling me to run faster. The worst part was waiting 15 minutes for the bus to transfer terminals. I am still shocked I made it.

CDG has a lot of separate terminals, it could help you to know which terminal are you landing into and where are you departing from. Probably, but absolutely not sure and I can't take responsability, you will be arriving at 2E and departing from 2F: in this case just the bare transfer would need 30 minutes, then add on top the time for immigration and security checks. (You have to do immigration, that is passport control in Paris, as Paris to Florence flight is internal to Schengen zone, so no immigration controls in Florence).
In my experience with a couple of similar cases, it can be done in one hour but it is a frantic thing and you really have to hope there is no delay in the incoming flight; in a case I have made it only for a delay in the outgoing flight.

The CDG structure with separate terminals may get really difficult to navigate - help yourself by studying a map in advance and there is also a website showing you, with appropriate photos, the itinerary to do. But if terminals are completely separate - for example you need to switch to terminal 2G, that involves waiting and then a 10 minutes shuttle bus run, a single hour is too short.

Emily!! I’m glad you made your flight and hope your Mom is doing well.

—> Back to the topic….