Ryanair

RyanAir has a well deserved reputation for charging low fares and charging for every conceivable extra.

If your backpack exceeds their specification you WILL be charged for it. Expect it to have to go in a sizer and on the scales at checkin. If you buy the checked luggage at the time of purchase of the ticket it will be less expensive. If they catch you at the check in desk it will be expensive. If they catch you at the gate it will be very expensive. They don't negotiate and they don't believe in the word "nearly" and they don't look the other way.

When you buy the ticket all this will be very clear and they will expect you to check a box that you understand it.

There was a (incorrect) rumour at one time that they were going to charge people for the use of the bathrooms and the CEO, Michael O'Leary, once jokingly said they would take the seats out to fit more fares in.

As Nigel said, with Ryanair always count on them to enforce the rules and charge you a lot extra if you don't follow the rules. If your backpack is too large, expect to pay extra. Even if it only a few mm to large.

This song might explain it a bit better: https://www.youtube.com/watch?v=ZAg0lUYHHFc

Ryanair has very strict baggage policies. I have flown with them several times pre-covid. I honestly, just paid to check my US-sized hand luggage. The rules must be followed. Ryanair will not go out of their way to get people home if there are strikes, natural disasters, etc., or you miss your flight for some reason or they cancel. They are not flexible at all. I tend to look at alternative carriers if I have a very tight fixed schedule.

margaret

I have traveled a lot in Europe using low cost airlines, similar to Ryanair e.g. Easy Jet, Vueling, Hop, & Transavia; but I have always shied away from Ryanair because I always read and follow the rules of every airline

The baggage rules change fairly often on Ryanair, but the advice remains the same. Unless you are parking most of your stuff at a home base and not bringing it on the flight, you will need to pay for additional luggage.

When you price your ticket, take the base price, add on Priority Boarding. This allows early boarding, plus guarantees your personal item will be in the cabin, up to a small carry-on bag up to 10 Kilo (22 lbs). Price varies now, from 8 to 22 euro, depending on route. Also pay to check a bag, up to 20 Kilo (44 lbs), that will run 21 to 60 euro, depending on route. So the add-ons will run 30 to 80 euros, but then compare the total cost with other airlines, and similar baggage allowances, Ryanair will still likely be less...but check Easyjet and other budget airlines, try Skyscanner.com for possibilities.

People who try to go too cheap on Ryanair, usually get burnt. They do check both weight and size. If you do not take priority, then you will only be allowed one small item to fit under the seat, so you at least will need to check a 10 kilo bag, which is a cost. Not sure what the penalty is, but usually it is being forced to check your bag at a higher cost. For a Ryanair flight, being point to point, checking a bag is no issue.

For what is worth, we paid for priority boarding on Ryan Air from Athens to Santorini and managed to bring on regular carry on bags that weighed more than specified above. No scrutiny really.

"Are they really particular about the size?"

In a word, YES!

In my somewhat limited experience, RyanAir will check both size and weight and you'll pay hefty fees if you're over the limit for either. My preferred budget airline in Europe is easyJet and paying a bit extra for the easyJet Plus membership provides some extra perks like another carry on bag, speedy boarding, etc.

Are they really particular about the size?

YES

I also see they have had a problem with cancelled flights. I don't know if it has been due to COVID or not. What have your experiences been?

"ACCEPTABLE" I will be on one of their flights in July. The 4th or 5th over the years. I prefer Wizzair.

Flew RyanAir once. They were extremely strict about size and weight.

I guess I can add some experience with checking bag size and weight. To be honest, vigilance has varied, but sided on the strict side. In the UK, it was every bag, done orderly, in a queue. In Germany, they had everyone at the gate, waiting, and agents walked around looking for suspicious bags, having people go up to the desk to check them out. In Croatia, they were much more lax, it was a return flight for most, back North, maybe that had something to do with it, but my experience with a lot of things in Europe, is as you go South, things just seem to be more relaxed in general. However, do not bank on it.

I can also add, my plans call for a Ryanair flight likely, Rome to Palermo, and Catania to Naples, I know for a 3 week trip I will not limit my bag to 10 kilo (a good bottle of wine maybe, a wheel of cheese, will blow away the 10 kilos in no time), so I will check a 20 kilo bag, yeah a few more Dollars, but also no worries and peace of mind.

There's a reasonable trade-off with Europe's bargain airlines. Follow the rules strictly and you can fly cheap. Try for extra, and you pay lots extra, in fact subsidizing the bargains for those who are careful.
While airline policies can vary, it's usually cheaper to buy all services in advance through the airline website. Check in on-line in advance too. These aren't dodges; the carriers carefully spell out everything on their sites.