A 45x36x20 cm bag is specifically designed to meet the "under-seat" cabin bag requirements for several European budget airlines, most notably easyJet. This size corresponds to approximately 18 x 14 x 8 inches, making it a small backpack or a very compact holdall. It is designed to fit entirely underneath the seat in front of you rather than in the overhead bin. This is the "free" baggage allowance that comes with a standard ticket; anything larger usually requires an additional fee. In terms of capacity, a bag of these dimensions holds roughly 32 liters, which is enough for a well-packed 2-to-3-day weekend trip if you use packing cubes and limit your footwear. Because budget airlines are increasingly strict with their measuring "sizers" at the gate, it is vital that the bag—including wheels and handles—does not exceed these limits, or you may be forced to pay a hefty "gate-baggage" fee (often €50 or more) to have the bag placed in the aircraft hold.