Ryanair is notoriously strict regarding its "small personal bag" policy in 2026. Every passenger is allowed one small bag (maximum 40 x 30 x 20 cm) that must fit completely under the seat in front of them. Gate agents frequently use "sizer" boxes to check bags that appear oversized; if your bag does not fit easily into the box, you will be charged an "oversize bag fee" (often £/€45.99 or more) to have the bag tagged and placed in the hold. To avoid this, it is recommended to use a soft-sided backpack rather than a hula-hoop style tote, as soft bags can be compressed to fit the sizer. Also, be aware that "duty-free" bags now often count toward your limit unless they can be tucked inside your personal item. If you have any doubt, purchasing the "Priority & 2 Cabin Bags" option in advance is much cheaper than paying the fine at the boarding gate.