Does the Peak Design Travel Backpack 45L fit United Airlines' carry-on?

No. Too deep by 0.1 cm. It's 23 cm front to back and United Airlines allows 22.9 cm. It's too big for United Airlines' personal item (12.8 cm too long). On United Airlines' cheapest fare the carry-on costs extra.

Won't fit

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Won't fit

Too deep by 0.1 cm. It's 23 cm front to back and United Airlines allows 22.9 cm.

BagPeak Design Travel Backpack 45L

Cabin bagUnited Airlines

Length: 56of 55.9 cm0.1 cm over
Width: 33of 35.6 cm2.6 cm spare
Depth: 23of 22.9 cm0.1 cm over

WeightNo published limit on United Airlines

Packed weightkg

Gate staff can still refuse a bag you can't lift into the bin yourself.

What you can do

Take a bag 55.9 cm tall or less. 3 bags we list fit.
Or check it in when you book. It's usually cheaper than paying at the gate.
Fits 4 other airlines, including Singapore Airlines and Frontier Airlines. See all

We haven't checked this bag's size against the brand yet.

See bags that fit United Airlines

United Airlines rules checked 2 Nov 2026. Source. Sizes include wheels and handles.

Side by side

Peak Design Travel Backpack 45L against United Airlines' limits. Bags can be turned, so the longest side is compared with the longest limit.

Carry-on: 55.9 × 35.6 × 22.9 cm
Side	Bag	Limit	Result
Length	56 cm	55.9 cm	0.1 cm over
Width	33 cm	35.6 cm	2.6 cm spare
Depth	23 cm	22.9 cm	0.1 cm over

Personal item: 43.2 × 25.4 × 22.9 cm
Side	Bag	Limit	Result
Length	56 cm	43.2 cm	12.8 cm over
Width	33 cm	25.4 cm	7.6 cm over
Depth	23 cm	22.9 cm	0.1 cm over

United Airlines rules worth knowing

Carry-on: 22 × 14 × 9 in. Not included on domestic Basic Economy unless you hold MileagePlus status or a co-brand card.
Personal item: 17 × 10 × 9 in, smaller than Delta's or American's.
No published carry-on weight limit.

Airlines where the Peak Design Travel Backpack 45L fits

Singapore Airlines Frontier Airlines Southwest Airlines AirAsia All airlines

Bags that fit United Airlines' carry-on

Biggest first.

CabinZero Classic 36L45 × 31 × 20 cmFits2.9 cm to spareBag page
WANDF Personal Item Duffel45 × 32 × 16 cmFits3.6 cm to spareBag page
Horizn Studios Gion Shoulder Bag27 × 18 × 5.5 cmFits17.4 cm to spareBag page

Good to know

What can I do if the Peak Design Travel Backpack 45L is too big for United Airlines?

Add a checked bag when you book, which is usually cheaper than paying at the gate, or bring a smaller carry-on. The Peak Design Travel Backpack 45L does fit Singapore Airlines, Frontier Airlines and Southwest Airlines.

What is United Airlines' carry-on size limit?

United Airlines' carry-on limit is 55.9 × 35.6 × 22.9 cm, with no published weight limit.

Which other bags fit United Airlines?

CabinZero Classic 36L, WANDF Personal Item Duffel and Horizn Studios Gion Shoulder Bag fit with room to spare.