The short answer
Yes, a backpack counts as a personal item if it fits under the seat in front of you, which on most US airlines means about 17 × 13 × 8 in or smaller (18 × 14 × 8 in on Frontier). A larger travel backpack (35–45 L) counts as your carry-on and goes in the overhead bin.
Personal item or carry-on?
Airlines don’t care what kind of bag it is, only its size. The same rule applies to a backpack, a tote, a duffel and a purse:
- Fits the personal item limit → personal item, free on every fare, goes under the seat.
- Bigger than that, within the carry-on limit (22 × 14 × 9 in on most US airlines) → carry-on, goes in the bin, and on budget fares costs extra.
- Bigger than the carry-on limit → must be checked.
Backpack size in liters
Backpacks are sold by volume, airlines limit dimensions. As a rough guide:
- 15–25 L (school or daypack): a personal item on every US airline.
- 25–32 L: a personal item on airlines with larger limits like Frontier, if not overstuffed.
- 35–45 L (travel pack): a carry-on. See carry-on travel backpacks.
Personal item limits by airline
| Airline | Personal item | Carry-on |
|---|---|---|
| Delta | Not publishedMust fit under the seat | 22 × 14 × 9 in56 × 35 × 23 cm |
| American Airlines | 18 × 14 × 8 in45 × 35 × 20 cm | 22 × 14 × 9 in56 × 36 × 23 cm |
| United | 17 × 10 × 9 in43 × 25 × 22 cm | 22 × 14 × 9 in56 × 35 × 23 cm |
| Southwest | Not publishedMust fit under the seat | 24 × 16 × 10 in61 × 41 × 25 cm |
| JetBlue | 17 × 13 × 8 in43 × 33 × 20 cm | 22 × 14 × 9 in56 × 36 × 23 cm |
| Alaska Airlines | Not publishedMust fit under the seat | 22 × 14 × 9 in56 × 36 × 23 cm |
| Hawaiian Airlines | Not publishedMust fit under the seat | 22 × 14 × 9 in56 × 36 × 23 cm |
| Frontier | 18 × 14 × 8 in46 × 36 × 20 cm | 24 × 16 × 10 inPaid61 × 41 × 25 cm |
| Allegiant | 18 × 14 × 8 in45 × 35 × 20 cm | 22 × 16 × 10 inPaid55 × 40 × 25 cm |
| Sun Country | 17 × 13 × 9 in43 × 33 × 23 cm | 24 × 16 × 11 inPaid61 × 41 × 28 cm |
| Breeze Airways | 17 × 13 × 8 in43 × 33 × 20 cm | 22 × 14 × 9 inPaid56 × 36 × 23 cm |
| Avelo | 17 × 13 × 9 in43 × 33 × 22 cm | 22 × 14 × 9 inPaid55 × 35 × 22 cm |
Making a backpack pass as a personal item
- Pack it, then measure it. A full front pocket adds inches of depth.
- Use compression straps to flatten it before boarding.
- Don’t hang things off the outside; a water bottle in a side pocket counts toward width.
Frequently asked questions
Does a backpack count as a carry-on?
Only if it is too big to fit under the seat. Most daypacks are personal items; large travel packs are carry-ons.
Can I bring a backpack and a carry-on?
Yes on most airlines: the backpack is your personal item and the suitcase your carry-on, as long as the backpack fits under the seat. Some basic economy and budget fares include only the personal item.
Is a laptop bag a personal item?
Yes. A laptop bag or briefcase is a typical personal item.