Rome Airport--When to Arrive?

The recommendation is three hours ahead of time. However, I flew out of FCO in June and found that two hours was more than enough for an international departure. It depends on many factors - time of day, airline efficiency, airport crowds, fast track options, etc. You will want to at least make sure that you meet the cut off times for checkin and luggage drop-off if applicable. Some airline checkin desks do not open until two or three hours before a flight.

Economy class lines often are longer requiring additional time for processing.

You might check to see when the check-in desks open. I have arrived at several airports very early only to find that they do not have staff until 5:00am (or later).

I second what Jack said. The upside is that you may very well be the first person in line at the check in counter when the desk opens if you get there 3 hours early.

You might check to see when the check-in desks open. I have arrived at several airports very early only to find that they do not have staff until 5:00am (or later).

Bingo.

We left our Rome AirBnB at 4am, upon getting there, it was us and 15 other parties at the airline's counter waiting to open, even then it took another 30-min for several more desk agents to start helping to work the line.

So...get there there at least 2hrs early, maybe earlier if you're anxiety ridden, and don't be surprised if you have to wait in line

My daughter flew out of Rome last week on a 6 am flight. She arrived at the terminal at 4:15 am. She sent me a picture - it was elbow to elbow with crowds and long lines already. In mid-January on a weekday. The check-in agents were already flat-out busy moving people through, this wasn't just heaving crowds milling around waiting for things to open.

The good news is that security is extremely efficient, so if you don't need to check bags, getting through to your gate is very quick and easy. Security is much faster in Terminal 1 (intra-Europe) than in Terminal 3 (international). I'm afraid I don't know which terminal handles flights to London, since they are not intra-Europe any more...but not really long-haul either.

It's roughly a half hour +/- from Monti to the airport. So maybe 4:30 am departure would do. 4:00 would absolutely cover it. The terminals are open 24/7, not sure exactly when the various check-in desks open. Maybe check with your airline? Probably American Air?

EDIT: by "fast security" I mean 5 minutes max in Terminal 1. You don't have to remove electronics, liquids, belts or shoes. You can take water through. You don't show your passport, just self-scan your boarding pass to get into line. The line never stops and there are LOTS of screening stations. I know, unbelievable but true. Terminal 3 is a little slower due to objections from the TSA to the new process for flights to the U.S. But they're working on making it better all the time. So, if you have carry-on only, go ahead and grab that extra half hour or 45 minutes of sleep.