In 2026, whether you can take both a cabin bag and a rucksack depends entirely on your airline's specific fare class. Most Full-Service Carriers (like United, Delta, or Emirates) allow one "Standard Carry-on" (the cabin bag) and one "Personal Item" (the rucksack/backpack), provided the rucksack can fit under the seat in front of you. However, many Low-Cost Carriers (like Ryanair, Frontier, or Spirit) have moved to a "Basic" fare that only includes the personal item; for these airlines, bringing a cabin bag plus a rucksack would require paying an extra fee. A supportive 2026 peer tip: many airlines now use automated "gate sizers" that use AI cameras to check bag sizes. If your rucksack is oversized and can't double as a "personal item," you might be forced to check it at the gate for a significant fee. Always check your digital boarding pass for your specific bag allowance before heading to the airport.