It won't. The Onward Bag is built to 40×30×20cm - the smallest cabin bag limit of any airline in Europe. It's been tested against every major sizer, including Ryanair, easyJet, and Wizz Air. But in the rare event you're stopped unfairly, our Gate-Proof Guarantee has you covered: we'll refund the full cost of your bag and pay the gate fee ourselves. In 25,000+ flights, we've never had to.