A backpack you bring as a carry-on has to fit the same limit as a wheeled bag: 22 x 14 x 9 in on American, Delta, United, Alaska, JetBlue, Hawaiian, Breeze and Avelo. Type your pack’s size, measured packed.
Bag type
Carry-on
overhead bin
Your bag against each airline
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Makers’ travel backpacks
Travel backpacks against 12 airlines’ carry-on limits, as of October 2026
Backpack
Outside size
Capacity
Carry-on limits it fits
Peak Design Travel Backpack 30L
20.9 x 13 x 7 in (53 x 33 x 18 cm)
27 L
12 of 12
Peak Design Travel Backpack 30L, expanded
20.9 x 13 x 7.9 in (53 x 33 x 20 cm)
33 L
12 of 12
Peak Design Travel Backpack 45L
22 x 13 x 9.5 in (56 x 33 x 24 cm)
35 L
4 of 12
Peak Design Travel Backpack 45L, expanded
22 x 13 x 11 in (56 x 33 x 29 cm)
45 L
1 of 12
Away Active Convertible Backpack 45L
21.7 x 13.6 x 9.5 in (about 55.1 x 34.5 x 24.1 cm)
45 L
4 of 12
Travelpro Maxlite Laptop Backpack
18 x 15 x 10 in (about 45.7 x 38.1 x 25.4 cm)
33 L
4 of 12
Each size and capacity is the maker’s own. Limits compared longest side to longest side.
Peak Design calls 35 L the 45L pack’s standard, max carry-on size, at 22 x 13 x 9.5 in. Expanded to 45 L it’s 11 in deep, which fits only Sun Country’s carry-on limit.
Same liters, different sizes
Away’s Active Convertible Backpack 45L and Peak Design’s pack expanded to 45 L share a liter figure, and their outside sizes differ: 21.7 x 13.6 x 9.5 in and 22 x 13 x 11 in. Compare the outside size with your airline’s limit, packed as you’ll fly.
Personal item or carry-on
A smaller backpack can go as your personal item instead: Delta, United, Southwest, JetBlue, Frontier and Breeze name a backpack among the things that go under the seat. See personal item backpack size.
Common questions
How many liters is a carry-on backpack?
Makers give different liters for packs of about the same size. Peak Design's Travel Backpack 45L is 35 L at its max carry-on size of 22 x 13 x 9.5 in, and Travelpro's Maxlite Laptop Backpack is 33 L at 18 x 15 x 10 in overall.
Do airlines measure backpacks?
Frontier says it checks the personal item's size at boarding, and United says a carry-on over the size limit can be checked at the gate. A soft pack counts at the size it's packed to.
Airline limits come from each airline’s own baggage pages, read in October 2026. Bag sizes come from each maker’s own product pages, read in October 2026. Checked against published data from Frontier Airlines, Sun Country Airlines, Avelo Airlines, Peak Design and American Airlines (plus 10 more).
See all 19 sources
American Airlines, Carry-on bags (aa.com)
Delta Air Lines, Carry-On Baggage (delta.com)
United Airlines, Carry-on bags (united.com)
Southwest Airlines, Carryon and Personal Item Policy (support.southwest.com)
General guidance from airline, TSA and FAA rules, checked on the date shown. Rules change, and the airline and security officers decide on the day: check your airline before you fly.