It depends on a variety of factors, including the airline, the route, the time of year, and the availability of seats. In some cases, upgrading at the airport can be a cost-effective way to experience Business Class perks without paying full price. In other cases, it may end up being more expensive.

While the idea of a "last-minute airport deal" sounds appealing, it is rarely cheaper than upgrading online in advance. Most airlines now use sophisticated algorithms to offer "discounted" upgrades via their apps or email in the days leading up to a flight. By the time you reach the airport, the airline has often already sold those seats or given them to high-tier frequent flyers. However, if seats are still empty at check-in, some airlines (like Air India or Lufthansa) offer a "Fixed-Price Standby Upgrade" which can be a good value. On the flip side, some carriers will charge you the "full fare difference" at the gate, which can be thousands of dollars. The best strategy is to check your airline app exactly 24 hours before departure during check-in; this is typically the "sweet spot" where prices are lowest before the airport staff takes control of the seating chart and flexibility vanishes.