How long to clear customs when flying into Rome?

Honestly, there is no "customs" to speak of. You'll be on line for passport control for maybe 10 minutes, assuming you're non-EU U.S. citizens. Then it's just a wait at the luggage carousel. Once you get your bags, you're out of there. Your wait for your luggage will depend on how many people on your flight have checked bags; indeed, whether you check your bags.

If your flight lands on schedule you will have no problem. You will be on a taxi no later than 9pm, including passport control, baggage claim, restroom break, snack at the coffee bar, and taxi wait. Actually what takes the longest in Rome is the baggage claim, in my experience.

Just to clarify for you as well...the wait is for Immigration/Passport control. That's where the official looks at your passport, stamps it and gives you leave to enter the Schengen zone for 90 days. The Immigration lines are usually divided in to EU Passports and Non-EU passports which is usually the longer line.

Once you get thru that you'll collect your bags (however long that takes) and then just walk thru a green door marked Nothing to Declare (unless you DO have something to declare) for the Customs part of it. The Customs officials can always stop you but I am just guessing you don't meet any of their criteria for extra searches so this is completely nothing to worry about.

We have passed through Rome immigration at least four times -- quickest was about 30/45 minutes and the longest 2.5 hours. All depends on the number of planes in at the same time and number of officers on duty. I would plan for at least an hour for immigration and maybe 30 mins for deplaning. Customs is a walk through the Green door. Just a question of how fast can you walk.

We have never flown directly from the US to an Italian airport. There was always some sort of hopper flight from other EU countries into Italy. That said, all the Customs stuff happens at this first point of entry, such as Amsterdam, Heathrow, Zurich, Munich, etc and never in Italy: These first places of landing in the EU are where we seem to have to go through customs. Landing in Italy, we have never had to go through Customs at all. Its the same flying out. Italy doesn't check, yet the hub you fly to, to get your US flight does. It is sometimes surprising after all the redundant TSA stuff going back to the US. Over-fed, and very sweet, drug sniffer dogs, is all we ever had to face. :)

Lets be a little clearer. You first point of entry in the schengen zone is where you go through immigration/passport control. If you have a continuing flight somewhere else in the Schengen zone, that is where you will go through customs. Customs and immigration are two completely different activities and functions. I know it is often referred to as one - customs - but it is not. If you didn't have a continuing flight then you go through both immigration and customs at the same airport. Since you are coming from the US to Italy directly you will go through immigration and customs in Rome.

And, please, the EU and the Schengen zone are not the same, either. For example, Great Britain was in the European Union and not in the Schengen zone. Now GB is trying to leave the EU. For most of European continent it is the rules of the Schengen zone that govern tourist travels via immigration.

You are flying direct into Rome from the US, so all this about going through immigration at the first entry point...that's Rome for you. You land in Rome, go to the passport line which can take a little while, then get your checked bags (also can take awhile, FCO is slow - carry on if possible), then walk through the nothing to declare door, then get to your BnB.

If your flight is close to on time you will be fine. I will be conservative here, adding lots of extra time, Let's say the passport line is long and takes 45 minutes (it's always been less for me), plus time to deplane and get to the line. You are out of there by 9:00 Then get your bags by 9:30. Out the door and to your BnB well before 10:30. BUT flights do get delayed. I would not advise a hotel with a HARD check in time on arrival day, because if your plane is delayed an hour then you are pushing it, and if it delayed more than that you will have no where to sleep.

I am a self-confessed worry-wart, especially when it comes to planes and being on time. I’d be spending the entire flight fretting over whether I’d make that curfew. Bottom line: get a different place to spend the night. Why add to the other stresses of a transatlantic flight? There are plenty of options near FCO.

I share Rosalyn's thinking. In all likelihood, you have enough time to make lights-off check-in. But "black swan" events do happen. With a early evening scheduled arrival, my personal inclination would be to book a near airport room then transfer the your longer term accommodation the next day. Alternatively, have a plan for arrival at dark B&B at 10:40PM.