How Ryanair measures your bag

Ryanair uses a physical sizer at the gate: a metal frame your bag has to drop into. There is no negotiating with it. Wheels, handles, feet and side pockets all count, which is why a bag advertised as “40cm” can still fail if the wheels add another two centimetres.

Buy to the external measurement, and treat the published figure as a maximum rather than a target.

The free bag is smaller than most people expect

Every Ryanair fare includes one small bag at 40 × 30 × 20cm. That is roughly the size of a large rucksack or a compact underseat case — not a cabin suitcase. It has to fit under the seat in front of you, so depth is the constraint people miss.

Ryanair does not publish a weight limit for the free small bag, but it still has to pass the sizer.

When Priority is worth buying

Priority & 2 Cabin Bags adds a second, larger bag at 55 × 40 × 20cm with a 10kg limit, carried in the overhead locker. You keep the small bag as well — the larger one is in addition, not instead.

Whether that is worth the fee depends on your trip. For a night or two, the free bag is usually enough. For a week, Priority plus a 55cm case is almost always cheaper than checking a bag.

What it costs to get this wrong

A bag refused at the gate is charged at the airport rate, which is considerably more than adding a bag when you book. That gap is the reason it pays to measure before you travel rather than hope at the gate.