Can I Bring a Backpack and a Carry-On?
On most major airlines, yes: the standard allowance is one carry-on for the overhead bin plus one personal item that fits under the seat, and a backpack counts as the personal item — the exceptions are Spirit and Frontier, where the carry-on is a paid add-on on every fare tier, and Air Canada's Basic fare, which allows a personal item only.
The one thing to know: Most U.S. basic economy fares (American, Delta, United, JetBlue's Blue Basic since Sept. 2024) include a full-size carry-on. Spirit and Frontier are the opposite: a carry-on bag is a paid add-on on every fare tier, not just the cheapest one — only the personal item is free. Air Canada's Basic fare (as of Jan. 2025) allows a personal item only, no carry-on, at all.
Two allowances, two size limits
The carry-on and the personal item are separate allowances measured against separate limits. Your carry-on is checked against the airline's bin-bag ceiling (22 x 14 x 9in on American, Delta, Alaska, and JetBlue; other carriers differ — see The Carry-On Size Table). Your backpack is checked against the personal-item limit, which varies much more: a tight 13 x 17 x 6in on Air Canada versus a roomier 18 x 14 x 8in on American and Spirit. The full breakdown is in What Is a "Personal Item," Really?
Where the two-bag rule breaks
Spirit and Frontier invert the usual deal: only the personal item is free, and a carry-on bag is a paid add-on on every fare tier, not just the cheapest one. Air Canada's Basic fare (as of Jan. 2025) allows a personal item only — no carry-on at all. And on Ryanair and easyJet, the free allowance is a small under-seat bag only. On those carriers, a well-chosen backpack isn't your second bag; it's your only free bag.
Sizing the backpack
If the backpack has to serve as a compliant personal item across airlines, size it to your strictest carrier's under-seat limit, not the roomiest. You can browse the category with this Amazon search for underseat travel backpacks — then check the listed exterior dimensions against your airline's personal-item row in our table before buying.
This page reports published airline policy facts as of the date above, not a guarantee for your specific flight or gate — gate agents have final discretion.
Frequently Asked Questions
On most major airlines' standard fares, yes — the allowance is one carry-on plus one personal item, and a backpack counts as your personal item as long as it fits under the seat in front of you. They are two separate allowances with two separate size limits.
Personal-item limits vary far more by airline than carry-on limits do — from a tight 13x17x6in on Air Canada to a roomier 18x14x8in on American and Spirit. A daypack that sails through on one carrier can be oversized on another, so check your airline's row in our size table.
Usually on U.S. legacy carriers: American, Delta, United, and JetBlue's Blue Basic (since Sept. 2024) all include a full carry-on plus a personal item on basic economy. The exceptions are Spirit and Frontier, where a carry-on is a paid add-on on every fare tier, and Air Canada's Basic fare (since Jan. 2025), which allows a personal item only.
Yes — how you carry them isn't regulated. What's checked at the gate is that you board with at most one carry-on for the overhead bin and one personal item that fits under the seat, each within its own size limit.
A bag that doesn't fit under the seat no longer qualifies as a personal item, so it gets treated as a carry-on — and if you already have one, you're over the allowance and the extra bag typically has to be gate-checked under your airline's own policy. Sizing the backpack to your strictest airline's under-seat limit avoids the whole scenario.