Suitcase Weight

A checked bag is always weighed at check in. A carry on bag may never be weighed, or it could be weighed or put in a "sizer" at the gate. This depends on the airline, the gate crew, and evidently the phase of the moon because it is never done on a consistent basis.

My experience is that almost anything goes on most US carriers when it comes to carry on. I have had Alaska and American Airlines count how many personal items I had and make me combine a back pack and a purse. I've seen people on other flights bring their entire wardrobe in many miscellaneous bags without anyone blinking an eye.

I think European Airlines may be a bit more strict.

For Europe and USA, I have only had my checked luggage at the check-in desk weighed. For checked luggage, there is about a 45 -50 lb. weight limit due to baggage handlers having to lift your stuff. You can remove items from your checked luggage at the check-in desk and move these things into your carry on bag to reduce the weight. Often, you can find a luggage scale available at an "unmanned" check-in counter and do this before approaching a desk clerk. The clerks prefer this, to save time.
You can also buy a luggage scale at places like Wal-Mart, Bed Bath and Beyond, etc. for not much money and do it at home. I think flights to Asia are much more strict about weight of personal, carry on items. I have never had any carry-on luggage or personal items weighed. Only larger, checked bags.

If your only flight is from the US to Italy, then back to the US on US carriers, then weight for a carryon is almost not an issue, unless you can not physically lift it into an overhead bin. Size is also not a great issue, as long as it fits through the TSA x-ray machine, and then fits into an overhead bin. If you are flying a European carrier, or especially a budget airline within Europe....then whole different story.

Every airport has a different procedure. Count on that they will be strict and weigh your carry-on bags.

This is highly dependent on the airline.

Some weigh carry on bags at check in. In one case I went straight to the gate (transfer from a domestic flight) and was turned away. I had to stand in the check in line, get my carry on bag weighed, receive a tag, then go through security.

Most airlines will not weigh the personal item and it is a way to skirt the weight limits. That said, some airlines now weigh the carry on and personal item together! And on other airlines a personal item isn’t allowed - it’s one bag only.

The only way to be sure is to go to the website of your airline and look up hand luggage requirements.

I have found that the policing of hand luggage Is very uneven. Sometimes they make me weigh it, other times they wave me through.

People that say it’s not a problem have just been lucky.

If I’m carrying a carry on and personal item I keep them separate until I’m in the air. There’s plenty of time to consolidate the bags into a single bag once you’re on the flight.

I think if you try to pack light, you shouldn't have a problem. I have not had anyone weigh my suitcase, but I travel with a 21-22" carry on. I have had airlines take my suitcase from me in Europe and check it, but simply because the smaller flights don't have the overhead bin space.

I had no problems with Delta when we flew to Rome in May. Carryon weighted 22#, but I worked hard to get it within Delta’s 9” depth measurement, ended up at 9 1/2”. Personal item was 14# including purse and camera. Delta didn’t care outbound; looked at it but didn’t question it coming home. Hope this helps.
You didn’t say who you’re flying on so size/weight restrictions could be different, especially with discount European carriers.

I’ve had my carry-on suitcase weighed at the airport, but only for Asian airlines. That occurred at check in.

I assume you will be flying Delta since you’re from Atlanta. I’ve never had anything weighed when flying Delta. But, I don’t pack heavy (16 lbs for suitcase/contents, 6 lbs light backpack with purse inside). Enjoy your trip to Italy! You will appreciate packing lighter when traveling in Europe!

Unless a bag is grossly overweight, most carriers don't care. They may be more interested in the size, however.
I recently flew out of Paris, and the gate agent looked at my 21" TravelPro and said it was too large. In reality, my 21' bag is actually 22" including the swivel wheels. I hee hawed around with the guy telling him I'd flown with it many times on their airline without any issue getting it overhead. I finally agreed to put the bag in the rack--knowing it was too tall--but he was too far away to see the bag's height. The lines were long and he let me through with my carryon.
Budget airlines are often out to make customers an example. Sometimes we travelers win and sometimes we lose.

If the airline has weight restrictions for carry-on (some do, some don't), it is possible that they will weigh it at check in. This has happened to me several times, especially in the last couple of years. I've never seen bags being weighed at a boarding gate. I've never seen personal items being weighed. I have seen people close to a check-in counter rearranging their stuff between bags, so sure, you can leave and shuffle things around.

If you're worried about small, heavy items, wear a coat or jacket with big pockets.

I take a 21-22” carry on bag and It has never weighed more than 22 pounds no matter how much I jam into it.

My flights are booked thru Delta - Atlanta to NY on Delta, NY to Rome on Alitalia. I've never seen Delta check size/weight of carry-ons but wasn't sure about Alitalia.

My pacsafe backpack is well within the size limits and weight limit for all US airlines but this December we will be flying back from Vienna on Austrian Airlines and they have a strict weight limit so we will probably have to check our bags and just take our small personal item with us on the trip home.

I wish there was an international standard that all airlines were required to use!!!

Our guide on a recent tour said that the last time she flew home to the States through CDG, her carry-on and personal item were weighed together. They came to over 20 lbs., and she had to go back and check one of them. She blamed the airport, but it had to have been the (unnamed) airline.

A possible hack that I used recently (on Transavia, a European budget with 1 carry-on/10 kg limit) was that I put my small day pack in my Rick Steves style backpack. I may have been a smidge over 10 kg, but I got in line to board right behind some young people from China that clearly didn't know the rules and were all trying to take on 2 bags (and no way they were going to be able to combine). The Transavia clerk was so busy dealing with them (i.e. charging them to check one bag each) that she didn't bother at all with me.

To summarize this thread - go to your specific airline(s) website and read their baggage protocols. If flying on different airlines - follow the most restrictive policies. Get a cheap luggage scale at the luggage section of someplace like Wal-Mart. (It's a handle with a strap. You connect the strap to your luggage and lift it just until the luggage is off the ground. Then, read the weight markings on the handle.)
Also, pay attention to the case outer dimensions. Every plane has different overhead bin sizes.
Packing cubes help.

Get a cheap luggage scale

^^Sound advice.I got a digital luggage scale about ten years ago. Not the cheapest possible option but not costly either.

It's still going strong, and is one of the smartest buys I ever made. Mine doesn't have a hook; it's got a strap that you can fasten around the handle of the bag you're weighing. I like that better. It's powered by 2 AAA batteries. That gadget has saved me aggravation and money. It's helped my fellow travelers as well, when I've brought it along on trips.

About weighing carry-ons. Long ago (2007), preparing for my first "big" international trip (Down Under, for almost a month), I carefully read all the material from the tour company. Which said that the airlines we'd be flying in-country had a weight limit for carry-ons. I think 8kg. That was a new one to me. We took several flights within Australia and NZ but only once - at the Queenstown airport - did I see carry-ons get weighed. I knew my plain Jansport daypack which was my carry-on, weighed a bit more than the limit. So I dangled it in a casual manner from one shoulder, as if it had nothing inside but feathers. The person ahead of me in the boarding line had a big rolling suitcase which the airline staff grabbed and weighed. They were so busy with her and her behemoth "carry on" that they gave me little more than a glance. Whew. Dodged that bullet. [Edited to add: the carry-on was heavy because I made a rookie mistake. Brought along a small laptop. Thought I'd use it a lot. Didn't after all. Even a small laptop really eats into a small carry-on weight allowance. ]