Ryanair is notorious for its strict enforcement of baggage dimensions, and in 2026, they continue to use metal "sizer" boxes at the boarding gates to ensure compliance. If your bag looks even slightly oversized, ground staff may ask you to place it in the sizer. For a "Small Personal Bag" (included in all fares), it must fit within 40 x 20 x 25 cm. If it doesn't fit—including wheels and handles—you will be charged a "Gate Bag Fee," which can be as high as €45 to €70, and your bag will be moved to the aircraft hold. For "Priority" passengers with a 10kg suitcase, the limit is 55 x 40 x 20 cm. Enforcement can be "hit or miss" depending on the specific airport and staff, but it is never worth the risk; always measure your bag while packed, as bulging pockets can easily push a compliant bag over the limit and lead to an expensive surprise right before you board.