I am a bit confused about what constitutes an acceptable "Carry-on" bag. For quite a while I have been using a Carry-on that measures 23.5 X 14 X 9.5 and have not had any issues with it. But I haven't flown International in quite some time, and looking at the baggage rules, I wonder if I can use this? Will soon be flying a few Delta One flights between JFK & Rome, Paris & Lisbon. I've also decided my old bag is pretty shot, and looking at a TravelPro Crew "carry-on" that states the dimensions are 23 X15.5 X 10. Will they refuse to allow that? They do sell a smaller size that is 21.5 X 14 X 9, but when I looked at that, it just seems too small. Thanks

23" is pretty big.
We have AmazonBasics 20" spinner which works just about everywhere - which they're now calling "21 inches".

(and this year we purchased three of the 26", and one 30", which to the eye, really aren't that much bigger...)
and to make things confusing... they now offer 20 > 24 > 28" sets...

If it's advertised as a carry on, then it should fit into MOST overheads' they will accept it. Since your flying on a widebody in DO I would say you'll have no problems.

Thanks for replies - I'm not as worried about that flight as I am about the JetBlue flight to get to the Delta flight. I have not had an issue before with older bags that measure 23, but I "hear" that they are cracking down somewhat recently. Sopke to someone today who was picked at random for a bag check, and her bag stuck out 1 " from the rack they use to test the bag, and she was forced to pay to check her bag. But that was on one of the "budget" carriers.

I'd say that it depends most on what airlines you fly frequently. My main airline is United which doesn't check carry on sizes as well, and my carry on bag (Tumi, softshell, continental dual access) would not fit in a carry on sizer, but all is well and it always fits, sometimes with a bit of a push.

Delta's official policy is 22x14x9 so it could happen. Realistically I've never seen it, especially not for J passengers. My concern would be what is your plan if you get called out for it on your flight home? Personally I would go with the smaller bag that fits the size limitations.

Swiss Airlines weighed my carry on bag for my last flight with no size check. Listing the European carriers may result in more specific warnings for your trip.

Just flew Delta (KLM) to/from Europe on economy, and nobody care about carry on size. Some of the ones I saw was absolutely HUGE about 3x the volume of my standard size carry on. The overhead bin (787) could fit 5 of my carry on and only 1 of those huge carry on.

Check out this chart for luggage size requirements...

https://www.carryonbagsizes.com/

Sorry to tag on this thread, but I'm also trying to decide between getting a 22-inch or 23-inch carryon (hardshell Monos maybe). All of the available info says that the max size is 22 inches (x 14 x 9), but literally every major manufacturer makes a 23-inch carryon (with a disclaimer that it might not fit on international airlines, especially within Asia). The lady at Nordstrom said that there would be a change in policy on US domestic carriers to extend the max length to 23 inches soon, but I doubt that she's got an inside scoop on the regulations. SO... what's the real story here? Should I get a 23-inch bag and hope it never gets measured and/or the rules change, or get the 22-inch bag and live within the rules but without an extra sweatshirt? Am I the only one that doesn't want to drop $400 on a bag that won't fit in the sizer? Will use this bag for domestic flights mostly and already have an international-sized carryon if that matters.

Just avoid US ultra low cost airlines like Spirit and Frontier. Departed DFW adjacent to a Spirit gate, I saw several passengers being asked to place their bags in the sizer then being hit with additional fees.

Please do not get something above the 22 inch. I had something less than 23inch but more than 21.5 and got caught to Air Canada's electronic sizer. I have been using this for a couple of years without any issue but then day they got me to put it on the electronic sizer it failed and I had to pay as an extra checked luggage. By the way I was able to put it in the physical sizer. International airlines, certainly in the Middle East and Asia are not too much bothered by the size compared to the weight.
But I really wonder how a lot of these back packs are allowed on board. They bigger ones are a menace to the passengers. Last week I got whacked on the head by a back pack. A rather large and heavy one on the back of a passenger who was trying to turn around in the aisle of a narrow body aircraft. They should be banned from wearing them while inside an aircraft. They can be carried as any other carry ons instead of on the backs.
I have a Monos carry on now and it fits everything. It is a good one so far.