Upgrading on KLM in 2026 is a flexible process that can be managed through several digital and physical touchpoints. Passengers can typically initiate an upgrade to Business Class (KLM's highest tier on most international routes) via the "My Trip" section on the official website or mobile app by paying the fare difference or using Flying Blue Miles. During the online check-in window, which opens 30 hours before departure, KLM often releases promotional last-minute upgrade offers at a reduced rate. Alternatively, self-service kiosks at the airport or agents at the transfer desk can process upgrades subject to seat availability. It is important to note that the cost of these upgrades can vary significantly based on the original booking class and the remaining capacity in the premium cabin. If you are a high-tier Flying Blue member, you may also be eligible for standby upgrades. For the most seamless experience, ensure your frequent flyer number is linked to your booking, as this allows the system to tailor available offers and point-redemption rates specifically to your profile and status.