Is a Backpack a Carry On?

Laura Lopuch

Usually, backpacks designed for travel — like the Outbreaker or Setout backpacks — are considered carry ons. School-style or daypack-sized backpacks are considered personal items.

Backpacks fall into this weird grey area for airlines’ carry on rules.

Most airlines allow you to carry on one personal item and one carry on.

In this article, we’ll clarify:

  1. What you can bring as a carry on
  2. How big your carry on should be

We’ll cover what’s generally accepted by airlines as their rules vary.

Is a Backpack a Carry On or Personal Item?

A broad definition of carry on is: a bag larger than a personal item which can fit underneath the seat in front of you.

So, a carry on is meant to fit in the overhead compartment.

Depending on the size of your backpack (bigger vs smaller), the backpack could be called a carry on or a personal item. Usually, backpacks designed for travel — like the Outbreaker or Setout travel backpacks — are considered carry ons. School-style or daypack-sized backpacks are considered personal items.

Here are example carry on sizes from a handful of airlines:

Air Asia

“You’re only allowed one piece of cabin bag on board that must not exceed 56cm x 36cm x 23cm including handles, wheels and side pockets. This bag must be able to fit in the overhead compartment.”

American Airlines

“Shouldn’t exceed 22 x 14 x 9 inches / 56 x 36 x 23 centimeters (including handles and wheels). Must fit in the sizer at the airport.”


“Baggage must meet carry on size limits (approximately 22″ x 14″ x 9″ or 56 x 35 x  23 cm). Reference size check templates located at ticket counters and gates.”


“Economy class customers are permitted one (1) piece of carry-on baggage that should not exceed 22 x by 15 x by 8 inches (55 x by 38 x by 20 cm) and must weigh no more than 7 kg (15 lb).”


“Dimensions for carry-on baggage: max. 55 x 40 x 23 cm.”


“The maximum dimensions for a carry-on bag are 9 inches x 14 inches x 22 inches (22 cm x 35 cm x 56 cm), including handles and wheels.”

To put it simply, carry on luggage dimensions vary by airlines.

The average size is 22 x 14 x 9 inches, making the Outbreaker or Setout backpack perfectly sized as carry on backpacks.

Carry On Backpack Rules

When it comes to carry on backpacks, you must adhere to two rules per the TSA.


According to the TSA website:

“You are allowed to bring a quart-sized bag of liquids, aerosols, gels, creams and pastes through the checkpoint. These are limited to 3.4 ounces (100 milliliters) or less per item. This is also known as the 3-1-1 liquids rule.”

Think of your quart-sized bag as your traveling bathroom bag filled with your face lotion, soap, toothpaste, body lotion, deodorant, and any other liquids you’re traveling with. When you go through TSA with your carry on backpack, pull out your quart-sized bag.

Must Fit Carry On Size Requirement

To bring your backpack onto the airplane, it must fall within your airline’s carry on size requirements. The average size of carry ons for the big airlines is 22 x 14 x 19 inches.

However, things get a little trickier for budget airlines as you’ll see below.

Backpack Carry On Rules for Budget Airlines

The carry on sizing rules change when it comes to budget airlines.

Expect to be charged for bringing larger and heavier bags with you. Expect to be charged for bringing more than one bag with you. Expect to be charged if you sneeze accidentally on the plane without asking permission. (Just kidding on that last one — well, kinda.)

Let’s look at the three biggest budget airlines: Spirit, Frontier and Ryanair.  

Spirit Airlines

According to Spirit’s website, “To keep ticket prices (Bare Fare™) low for everyone, we charge for carry-ons and checked bags. We charge more for checked bags over 40 lbs. This is because the added weight requires more gas for the plane. One personal item that fits entirely in the smaller sizer box (like a purse, small backpack, etc.) is included with your ticket. Another personal item or anything larger like a standard carry-on or checked bag will need to be paid for.”

So, what does a carry on bag look like according to Spirit?

Again, from their website:

“Carry-on bag: Maximum of 22 x 18 x10 inches (56 x 46 x 25 cm) including handles and wheels. We may require that a carry-on bag travel as a checked bag if it cannot be safely stowed on a particular flight.”

In other words, you’re looking for a backpack like Setout Divide — measuring 20 x 13x 6” and expands up to 8” — or the 35 L Setout travel backpack — measuring 22 x 14 x 9”. 

Frontier Airlines

Frontier refers to their carry on dimensions as “just enough room for your next adventure.” What size carry on DOES your next adventure fit into?

From their website: “Make sure your bag fits… 10” Depth, 16” Width, 24” Height, <35lb Weight.”

Also, you should note that carry on bags must fit in the overhead bin. And you will pay for your carry on bag vs the bigger, non-budget airlines. That carry on bag price will “vary based on when you purchase and are non-refundable.”


Ok, hang tight with me, because things are getting a little complicated. Ryanair has several options for you when it comes to carry on bags.

Priority & 2 Cabin Bags Ticket or Plus/Flexi/Family Ticket

You can bring “1 additional 10kg bag on board which must fit into the baggage sizer (not exceeding 10kg and dimensions 55cm x 40cm x 20cm).”

Don’t have that ticket?

You’re allowed to bring 1 small personal bag “on board which must fit under the seat in front of you (40cm x 20cm x 25cm).”

Prepare to pay for the privilege of bringing your carry on onboard. Or getting very creative (aka minimalistic) in your packing.

According to My Baggage:
“Non-priority customers can only bring one small bag (40cm x 20cm x 25cm), that must fit into the sizer. If non-priority customers want to bring a second bigger bag, they can purchase a lower cost 10kg check-in bag for at time of booking online. It must be checked-in at the airport bag drop desk, prior to reaching airport security.”

Don’t have a priority ticket and didn’t plan ahead?

Yikes, you’ll likely be adding a 10kg bag to your ticket for a higher price than if you’d bought it when you got your tickets.  

A Way Around The Budget Airline Conundrum

Maybe, like me, you’re looking at these budget airlines and thinking, “How great it’d be to save big money on the ticket price… and stuff is just stuff, right? I don’t need stuff to make for a great trip.”

Yeah, sound familiar? You can pack for a 5-day trip in a bag that’s sized as a personal item, like the Setout Laptop Backpack, but with the interior organization of a carry on.

With dimensions of 18.5 x 12 x 6.75 inches, the Setout Laptop Backpack is deemed a personal item per Frontier and Spirit’s personal item requirement of 18 x 14 x 8 inches.

Before you roll your eyes and think, “She’s clearly crazy,” hear me out.

Because I’ve successfully done this experiment on a 5-day trip to Alaska flying Frontier Airlines.

If I can do it, so can you. Here are my secrets.

When you pack, consider every item in your backpack and ask:

  • Is this necessary?
  • If I don’t bring this, can I buy it there?
  • Do I really need this?
  • Is this irreplaceable on the road? Or a HUGE hassle to replace if I left this at home? (example: prescription glasses or contacts, medication)

If you do try this experiment, you might be surprised by how little you *actually* need for a successful trip… and by how free you feel.

Which Backpack is the Best Carry On Item?

Well, that depends on what kind of travel you’re doing.

Traveling with a laptop? The Setout or Outbreaker backpacks both have robust straps and a sleeve for your computer.

Worried about rain? The Outbreaker backpack is made of waterproof sail cloth.

Might need extra room on the road? The Setout Divide backpack is expandable, going from 26L to 34L in a few seconds.

Thinking you might have to check your backpack on those budget airlines? The Setout or Setout Divide backpacks have packable shoulder straps, transforming your backpack into a sleek bag. Attach the shoulder strap to carry like a duffle.

Compare the three best below:


A carry on backpack must adhere to these rules to be considered a carry on:

  • Fit within your airlines’ carry on size requirements (beware: these vary depending on airline)
  • Place all liquids within a quart-sized bag and liquids must be under 3 fluid ounces
  • Budget airlines are stricter with their carry on requirements; most make you pay to carry on, but…
  • Sidestep that conundrum and pack lighter in a backpack the size of a personal item
  • Outbreaker, Setout or Setout Divide: which backpack is best for your carry on needs? Depends on the type of travel you’re doing.

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