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

Yes. Fits with at least 2.4 cm to spare on every side. It's too big for Frontier Airlines' personal item (10.3 cm too long). On Frontier Airlines' cheapest fare the carry-on costs extra.

Fits

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Side the bag fails onPart that sticks outSizer frame

Fits

Fits with at least 2.4 cm to spare on every side.

BagPeak Design Travel Backpack 45L

Cabin bagFrontier Airlines

Length: 56of 61 cm5 cm spare
Width: 33of 40.6 cm7.6 cm spare
Depth: 23of 25.4 cm2.4 cm spare

Weight15.9 kg limit

Packed weightkg

Empty it weighs 2 kg, leaving 13.9 kg for your things.

What you can do

Frontier Airlines charges for this bag on the cheapest fare, so add it when you book.

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

See bags that fit Frontier Airlines

Frontier Airlines rules checked 2 Nov 2026. Source. Sizes include wheels and handles. Some details are still being confirmed.

Side by side

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

Carry-on: 61 × 40.6 × 25.4 cm, 15.9 kg
Side	Bag	Limit	Result
Length	56 cm	61 cm	5 cm spare
Width	33 cm	40.6 cm	7.6 cm spare
Depth	23 cm	25.4 cm	2.4 cm spare

Personal item: 45.7 × 35.6 × 20.3 cm
Side	Bag	Limit	Result
Length	56 cm	45.7 cm	10.3 cm over
Width	33 cm	35.6 cm	2.6 cm spare
Depth	23 cm	20.3 cm	2.7 cm over

Empty it weighs 2 kg of the 15.9 kg limit.

Frontier Airlines rules worth knowing

Carry-on: 24 × 16 × 10 in, 35 lb. Always a paid add-on.
Personal item: 14 × 18 × 8 in including straps, wheels and handles. Strictly enforced with a sizer.
Spirit Airlines used the same 18 × 14 × 8 in personal item before it stopped flying in 2026.

Airlines where the Peak Design Travel Backpack 45L fits

Singapore Airlines Southwest Airlines AirAsia All airlines

Bags that fit Frontier Airlines' carry-on

Biggest first.

Samsonite Freeform Carry-On Spinner58.4 × 38.1 × 24.8 cmTight0.6 cm to spareBag page
Away Bigger Carry-On57.7 × 39.1 × 24.4 cmTight1 cm to spareBag page
Rimowa Essential Cabin55 × 39 × 23 cmFits1.6 cm to spareBag page
Travelpro Maxlite 5 21" Expandable Spinner58.4 × 36.8 × 22.9 cmFits2.5 cm to spareBag page

Good to know

Will the Peak Design Travel Backpack 45L still fit Frontier Airlines when it's packed?

It should. It has 2.4 cm to spare on its tightest side, and a stuffed front pocket usually adds 3 to 5 cm, so don't overfill the outside pockets.

What is Frontier Airlines' carry-on size limit?

Frontier Airlines' carry-on limit is 61 × 40.6 × 25.4 cm, up to 15.9 kg.

Which other bags fit Frontier Airlines?

Rimowa Essential Cabin and Travelpro Maxlite 5 21" Expandable Spinner fit with room to spare. Samsonite Freeform Carry-On Spinner and Away Bigger Carry-On are right on the limit.