Is my bag too big for carry on - Aer Lingus

Many airlines have a sizing box that determines the acceptable dimensions. If your bag cannot be fitted into the sizer, you cannot carry it on. If your bag is "squishable" enough to get into the sizer, you might be OK, but they still have a strict weight limit.

I know this is a kind of "breaky rules-y" answer (and I am a nice, careful, law-abiding person) but I always travel with the same sized bag (a gym bag) and I have rarely-to-never seen anyone with a bag that is within a believable percentage of the "legal" sized carry-on get challenged. Sure, once in awhile someone gets WAY over-the-top with a potential carry-on and they are asked to check the bag, but mostly? Egregiously over-sized GIANT suitcases get lugged aboard as "carry-on bags" and are allowed. If you can cram it into the little sizing thing, you can definitely carry it aboard. And you'll be AMAZED at what folks have the stones to haul with them. HUGE suitcases! GIANT things, plus an auxillary bag. Airlines I've flown recently include a majority of the major carriers, so this isn't from a small selection of trips.

Since the airline you are asking about is Aer Lingus, it is only their opinion that will count. What happens on other airlines is of no importance or validity. The weight limit for carryon on Aer Lingus is 22 lbs. If your bag fits in the sizer and is under 22 lbs, you can carry it on. Otherwise you will have to check it (and it needs to be under 44 lbs). They have become very strict about their requirements in recent years, so expect it to be sized/weighed.

We flew Aer Lingus in May: Boston-Dublin and Dublin-Boston. We had purchased luggage based on Rick Steves recommendation regarding size. I was upset to find out his recommendation was too big per the Aer Lingus requirements so we checked our bags rather than carry them on. HOWEVER: many passengers carried bags on board that were GROSSLY over the Aer Lingus maximum requirements. Also many passengers clearly exceeded the number of bags allowed per person to be carried on board. Nowhere did I see a "sizer" to measure the size of the bags. Neither did I see anyone asked to remove an oversized bag from onboard.
I should mention that both flights were absolutely packed so it wasn't a matter of "half-full" planes. Am I suggesting you exceed the recommended size limit? Nowe followed the rules and especially on our flight home I knew our breakable items (which were in a smaller bag carried on) would not be taken away from us and checked in. Bottom lineI disagree with Nancy's assessment that Aer Lingus strictly enforces their "rules". Would I personally carry on a bag that was grossly over the size limit? No. Would I worry that my bag was 1" over the 8" limit? No way!!!

Pat is correct, Aer Lingus can be very accomodating about the size of your carryon luggage unlike other airlines like Ryanair, however all you need is one jobsworth who enforces the rules.

Thank you all for your posts and wisdom. I am flying from Munich to Dublin - don't know if either will fuss over it as long as it is under 22 pounds.
Do you think I will I have time to check it in (if I am there on time) - if I try to take it as a carry on and it is not allowed?

Yes you should Patty, either at the checkin desk or at the boarding gate