On TAP Air Portugal, a backpack can absolutely be considered a "personal item," but it must meet the airline's strict 2026 size and weight limits. To qualify as a free personal item, your backpack must be no larger than 40 x 30 x 15 cm (16 x 12 x 5 inches) and weigh no more than 2 kg (4.4 lbs). It must be small enough to fit completely under the seat in front of you. If your backpack is larger than this—like a standard "school" or "hiking" pack—it will be classified as your one piece of "hand baggage" (carry-on), which has a more generous limit of 10 kg and 55 x 40 x 25 cm. Many travelers mistakenly bring a full-sized backpack as a "second" small bag and are forced to pay gate-check fees. The key for 2026 travelers is to use an "underseat" style backpack if you intend to carry both a suitcase and a pack, as TAP has become more aggressive about weighing and measuring bags at the gate.