Carry On for 11 days in Italy? Back pack or roller?

you need to consider specific measurements, not volume, when buying luggage, and measurements will vary between airlines. Your flight airlines will provide size, number of items and weights on their website. But for a quick look, that may help find a 'average' size, there are a number of websites with charts of dozens of airlines and their baggage allowances. Here's just one. https://upgradedpoints.com/travel/airlines/checked-luggage-size-chart-allowances/
Also, if you haven't found it, this travel forum has a Packing section and luggage is discussed every week.

I would start here:

https://www.ricksteves.com/travel-tips/packing-light/backpack-or-rolling-bag

Once you have decided what you are looking for, you can tailor a search on this site for "two-wheeled carryon" or "hardside underseat bag" or whatever.

You aren't crazy to try carry-on only. Many on this site have done it for trips two weeks and longer. Look at the "packing" section of the forum and you'll find many suggestions. There are lots and lots of Youtube videos on how to pack with just a carry on and a personal item. One strategy is to make sure that your tops will go with most, if not all bottoms, creating basically a capsule wardrobe. Plan on bringing clothes for seven days and do laundry. You can do sink laundry, go to a laudromat or book somewhere that has a washing machine. Limit shoes and wear your heaviest items on the plane. Decant toiletries to a smaller container - often 100 ml is much more than is needed for even two weeks. Good luck!

Here's a news flash for you, you don't do it to avoid checking a bag, that is a misconception.

You do it, first, to really make you think about what you are bringing. What do you really need? You do not need to bring everything for every eventuality, a weeks worth of clothes (or less) is fine.

You do it second because hauling a huge bag or multiple bags is really troublesome on public transport, along cobbled streets, and up and down stairs, or the tiny elevators many hotels have.

I do usually just carry-on on the way to Europe, mainly to mitigate the risk of lost luggage, and, usually, I land and are off traveling, making it difficult for a bag to catch up with me if there is an issue.

On the way back home, I almost always check my bag.

Since you likely will not be taking an intra-Europe flight, 45l will be fine, you decide if it is a two or four wheel, or a backpack type.

I have a 35 liter bag that has nice big wheels, but also can convert to a backpack, seems to work well. I also have a book bag type backpack I take, for small items, my laptop, and other things.

For reference, I probably can travel indefinitely with just those two items, did 6 weeks earlier this year that included both Southern Spain (warm to hot) and the Netherlands (cooler and rainy) and did just fine.

Not crazy at all, Ron. Lots of people do it every trip they take. I’d guess probably half the people who will chime in are carryon people and do it every time. I travel solo and have done the trip you’re doing about 10 years ago and definitely did carry on. It’s great to not have to worry about heavy bags getting on and off trains etc.

I find it very helpful to make a list of clothing to take, lay it all out and do a couple of trial packs way ahead of time. Italy is wonderful, you will have a great time. Good luck.

We always only do carry-ons, including for winter travel in Canada, so it can certainly be done! I wouldn't prioritize getting the largest bag, but instead look at how well organized the bag is, and how comfortable it will be for you to carry, lift over your head etc. We don't have rolling bags, and as such it is lighter for me, and I can still easily lift when I'm by myself, however it does mean I have to carry it. Ours has both back pack strap and an optional across the body strap.
The hardest thing for me, is how many pairs of shoes I can get away with. I try to take a good walking pair and a lighter, pair for dinner ( and maybe an extra pair of sandals). For some women sacrificing hair products can be an issue, but you can buy small containers for those.
For colder times, thin layers are the way to go, merino wool can go a long way. Pack for the best case scenario as you can always buy stuff in Itally! That is part of the fun.

Ron and wife, Carry-on only is not crazy. No waiting at the luggage carousel. No lost luggage. But it is a challenge to meet size and weight limitations whether airline or self-imposed. Make a detailed packing list; do a test pack; revamp packing list; repeat as many times as needed to reach your goal.

I spent today doing multi test packs for a month trip in two weeks. I ended up within striking distance of my goal, but still need to get the bulk down. Packing clothes is not the problem. It’s all the older person supplies that take up room. All else fails, I can pack less and buy things in Italy.

Back to more test packs to cut a few more pounds. You’d think I’d have this figured out after four trips.

EDIT: I should have added that I use a RS Rolling Carry-On and a discontinued RuMe lightweight tote (7 oz).

I spent 4 weeks in Europe last year with a carry-on bag so it can be done. I have the Farpoint bag from this review by Wirecutter https://www.nytimes.com/wirecutter/reviews/best-travel-backpack/ which is 55L and more-or-less carry on size (some foreign carriers have smaller dimensions). A handy source for limits is https://travel.usnews.com/features/carry-on-luggage-sizes-size-restrictions-by-airline although you should always check the airline site to confirm. The bigger problem isn't size, it's the restrictive weight many airlines have. Some have 8kg limits and they may add your personal item and carry on bag together. I can't make that limit so I pick my flights carefully.

@ Ron

Seems to me to be a great title for a slap-up comedic English movie.

Regards Ron

I travel in 3 months segments. I do it with a carry on rolling bag and a personal item size backpack.

Theoretically, I could travel longer but I need to return to home base to refill prescriptions.

You've gotten good advice so far but let me add one thing.

The choice of wheels or no wheels is personal. There is no right or wrong except what it right or wrong for you.

If you have never traveled with a backpack, here's what you need to do. Get hold of one. It doesn't have to be one you would travel with. Just one that can hold about 20 lbs of stuff.

After it's loaded, put it on and take a walk. Not just around the house. Around the neighborhood. Include steps if you can. Go for a good 30 minutes. Then when you get home and take it off, ask yourself if you want to do that every day of your trip. If yes, go find one that fits your needs. Many people here travel that way and can make suggestions as to brands.

If you don't like it, then start deciding on a lightweight rolling bag. Whether it's two wheels or four wheels is also personal preference.

Additionally, there are many videos on the internet showing different ways to pack a carry on bag. Again, no one way is correct. The only right was is the one that is right for you.

Check your specific airline for dimensions and weight limitations. Sometimes they don't check them before you board, but sometimes they do, so an inch or a lb. beyond what they state you can bring can become an expensive problem. Also, when you're measuring your bags, don't depend on the measurements stated on the box or in the advertisement. Use a measuring tape because often they don't include the wheels, but the airlines will if they put your bag in the measuring box. Venice has stairways everywhere, over and over, so make sure you can comfortably carry your bags up and down lots of stairs. Each of the cities you've mentioned has cobblestone streets and sidewalks, so if you use rolling bags, be sure they're tough ones.

Have a wonderful trip. You've picked some great cities!

We've used both. In 2002, we took a 10 day trip to Scotland. We each bought the classic RS backback. Other then a personal bag, that's all we took. When we checked in our flight from Toronto to Glasgow, they asked about our checked luggage. When we said we didn't have any they were incredulous. We still have and use those backpacks, they are very durable and have lasted well.

Fast forward to last December. We took a 14 day trip to Austria and Slovenia. For this trip we bought the RS roller bags (not the spinner bags). They worked great!

Between those two trips we've been to Europe several times, as well as Central America and Africa (Deb only, it was a medical mission trip). We almost always pack light.

For you I'd lean towards the RS roller bags. They have a hard half shell that works well for train/bus travel and checking your bag, if need be. Our flight home from Munich was packed, so we took Delta up on their offer to check our carryon. It worked out well, we didn't have to fight other passengers for precious overhead bin space.

We travel quite a lot and could never to a 11 day or 14 day trip with only carryon.

To those that do so, how often do you wash clothes?

At the risk or repeating what others have said, the weight and size restrictions of your airline(s) will determine what sort of carry on bags you can use. It you are flying one of the US legacy carriers like United or Delta the size and weight limits will be easier to meet. But if flying Iceland, Lufthansa or Condor the limits are much more restrictive. As a general rule backpacks will be lighter than roller bags. But to make a backpack work you need to make sure it fits you well. And while a larger backpack may fit you, it may not fit your wife. Just to give you my own personal experience I'm a short 60 something female who traveled last September to Northern Italy for 2.5 weeks. I attended a wedding (cocktail attire requested), hiked and biked. I got it all into a 38 liter Osprey Fairview XS/S backpack (now discontinued). All in my bag weighed 7.3 kg. So you can do it. But it takes planning and an accurate digital scale.

We travel quite a lot and could never to a 11 day or 14 day trip with only carryon. To those that do so, how often do you wash clothes?

We don't wash. I normally take 2 pairs of pants and three shirts. That gives me 3 pants and 4 shirts. I take three pairs of socks and 4 changes of underwear.

As already mentioned, make sure whatever you go with meets your airline mandatory dimensions. My biggest recommendation is to go with the most lightweight one that matches your needs, My preference is for a softsided, two wheeled carry on. ( Two wheels vs 4 wheels is a matter of personal preference - I prefer 2 because the wheels are more closely imbedded into the frame).