The Ultimate Carry On Backpack Size Guide for Smart Travelers

Carry-on backpack sizes are confusing. There seems to be an endless array of options and volumes. Plus, backpacks come with so many different styles, attachments, zippers, and pockets just don’t always make sense.

You’ve got your trip all figured out. Flight plans? Scheduled. Hotel reservations? Booked. An itinerary that meticulously tracks everything you’re going to do every waking hour? Primed and ready. But when it comes to carry-on backpack size, you might still be a little lost at that. You don’t want to bring a bag that is so oversized because you’re definitely going to have unexpected fees for that. Airlines have strict size limits. So, bringing a bag of the right size will save you from unexpected delays.

In this article, you’ll learn the basics: the standard dimensions of carry-on backpacks for domestic and international flights, how personal items and carry-on differs, and how to measure your backpack. Aside from that, you’ll also understand the weight restrictions, how you can choose the right liter capacity, tips how you can fit a large backpack into the overhead cabins. And lastly, since the rules aren’t consistent, you’ll also know the common airline-specific rules for budget carriers. With these, you can be sure that your bag is ready to travel with you.

And if you’re travelling with your family, it is more important that you have the right carry-on backpack size. And it needs to be both compact and highly functional at the same time. Since travelling with essentials like an infant car seat and stroller is already complex. With the right size, you can store diapers, snacks, documents, and a change of clothes without the feeling of being bulky or unmanageable.

Standard Dimensions for Domestic Carry-on Backpacks

In the United States, the standard dimensions for domestic carry-on backpacks are around 22 x 14 x 9 inches. This already includes the handles, wheels, and external pockets. The backpacks in these sizes usually fit in the overhead cabins on the majority of airlines.

Aside from the height and weight of the backpack, the depth and structure are factors you need to consider, as well. Backpacks that are overstuffed can still exceed the size limits even if the listed dimensions are compliant.

Go for backpacks with compression straps and a smart compartment layout, especially if you are carrying extra items for your kids. In this way, you’ll stay within the size rules.

International Size Limits and Why They Are Smaller

When it comes to international flights, the recommended carry-on backpack size is usually smaller. Most international airlines, especially European and Asian airlines, operate smaller aircraft. Aside from that, their priority is the efficiency of the cabin space, and this directly affects the allowed carry-on backpack size.

Every airline is different, but the international carry-on limits range between 21 x 15 x 8 inches. These limits can even go smaller on budget airlines. Some carriers also apply weight limits. This means your bag should be only 7-10 kg, regardless of the physical dimensions of the bag. Your bag can still be rejected if it’s too heavy, even if it fits the size requirement.

International flights have way stricter limits because they tend to serve more passengers per cabin. They also have narrower overhead cabins and emphasize faster boarding times. Budget airlines also depend on baggage fees as a source of revenue. And this makes the compliance more important for travellers trying to avoid extra charges.

Personal Item vs. Carry-on: Knowing the Difference

Personal Item

A personal item is a smaller bag, which you bring onboard the plane, but store under the seat in front of you. This can be a purse, a laptop bag, a tote bag, or anything that can fit in the cube-shaped space under the seat. The typical size of a personal item is around 18 x 14 x 8 inches, but it can still vary by airlines.

A compact diaper backpack or essentials pack along with an infant car seat and stroller, may qualify as personal items, depending on the policies of the airlines.

Carry-On

A carry-on is the primary bag you bring onboard a plane and store in the overhead bin. This one is larger than the personal item, and can also be placed in the overhead bin. This is also where carry-on backpack size rules become important. As mentioned, there are airline dimension requirements that carry-ons need to meet.

Carry-ons are also more likely to be measured or checked during busy flights or on international routes. Don’t try to overpack or exceed the size limit if you don’t want forced gate-checking and added charges.

How to Measure Your Backpack Including Straps and Handles

Measure your carry-on backpack to know if it is still under the carry-on backpack size requirements. Now, this is where many of the travellers make mistakes. They only measure the main body of the bag. Airlines measure the whole backpack, including the straps, handles, and external pockets. Here’s how you can measure your backpack in the right way.

1. Put in the bag the things you need for travel. Make sure that it is fully packed.
2. Place the backpack on the floor or a table in an upright position. This way, you can measure it accurately and the measurements you get are consistent.
3. Now, measure the height. Start from the bottom of the backpack to the highest point. Include the top handle, rolled fabric, or extended frame.
4. Then, measure its width. Measure across the widest part of the backpack from side to side. External pockets or bulging sections are also included in the measurement.
5. Measure also the depth of the backpack. Start from the front of the bag to the back, accounting for expandable compartments and packed-out pockets.
6. Make sure you tighten, tuck in, or fold shoulder straps, hip belts, as well as the compression straps. In this way, they won’t add extra inches to the overall size.
7. Always double-check the airline limits. Compare your measurements with your airline’s stated limits. Keep in mind that the airlines not just measure the main compartment, but also the entirety of the backpack.

Understanding Weight Restrictions for Cabin Baggage

Size limits are not the only thing you should watch out for. Weight restrictions for cabin baggage are just as important, too. Many travellers think that if their bag fits in the overhead cabin, it’s acceptable. But the truth is, several airlines, particularly international and budget carriers, have strict weight limits.

Usually, in domestic flights, the weight limits are not that strict. They only rely on the size compliance. But it’s different for international airlines because they have cabin baggage weight limits between 7-10 kg. Some carriers will weigh your backpack at check-in or the boarding gate. When you exceed the limit, it can lead to forced checking or you’ll have additional fees.

Airlines have weight restrictions, mainly because of the safety of the passengers as well as to maintain the balance on the aircraft. A backpack that is packed with heavy items, like electronics, books, or liquids, can easily exceed the allowed weight despite meeting the size requirements.

Choosing the Right Liter Capacity for Your Trip Duration

The right liter capacity will tell you how much you can pack without exceeding the limits imposed by the airlines. The capacity of a backpack is measured in liters. And that directly affects the weight and overall travel comfort.

• Short Trips (1-3 Days)

If you’re on for a short trip, say 1-3 days only, a 20-30 liter backpack would be enough for you. This size works really well for business trips, as well. They can fit clothing, toiletries, and essentials. Additionally, they can easily fit under the seats or in the overhead bins.

• Medium Trips (3-5 Days)

For medium trips, like 3-5 days, a 30-40 liter backpack works well. With this capacity, you have enough room for your multiple outfits, shoes, and electronics. This is also the go-to capacity of most travellers for its flexibility.

• Longer Trips (5-7 Days)

If you’re going on longer trips, like 5-7 days, the backpack capacity for you is the 40-45 liter backpack. This capacity pushes the upper limit of standard carry-on backpack size, so you need compression straps and careful packing to remain compliant on airline rules.

Tips for Fitting a Large Backpack Into Overhead Bins

Yes, your backpack meets the maximum carry-on backpack size, but it can be a little difficult to fit it into the overhead cabin. Here are tips so you can fit your large backpack into the overhead bins in the airplanes.

1. Tighten the internal and external straps of your backpack. Do this to reduce its volume.
2. The jackets or scarves or other compressible items should be placed in the external pockets or along the edges. In this way, it is easier to slide the backpack into tight spaces.
3. Place your backpack upright with the back panel against the bin wall. Or if the bin is short in height, just lay it flat.
4. Remove the items that are protruding, like water bottles, infant accessories like an infant car seat and stroller parts, or bully jackets. Just stow them separately or under the seat.
5. If your backpack is oversized or the overhead bin is full, your only choice is to gate-check it. Don’t worry because your bag will still arrive at your destination.

Common Airline-Specific Rules for Budget Carriers

It is mentioned that budget airlines have stricter rules for carry-on backpack size and cabin baggage. Below are some of the common airline rules to help you avoid unexpected fees or having to gate-check your backpack.

• Many of the budget carriers, specifically in Europe and Asia, limit carry-on dimensions to around 21 x 15 x 7-8 inches. These dimensions are typically smaller than U.S. domestic limits.
• Budget carriers have cabin baggage weight limits between 7-10 kg. Not like traditional carriers, they may weigh your backpack at check-in or boarding, with fees for anything heavier.
• There are budget airlines that only allow you to bring a very small personal item. Additional items, like compact diaper bags or small backpacks, may have extra fees.
• Gate-checking is required if your backpack exceeds the size or weight limits. This means your bag will be stored in the hold during the flight, even if you intended to carry it onboard.
• Unlike full-service lines, most of the budget carriers will charge for all checked luggage. With that being said, it is better to stick to the allowed carry-on backpack size to avoid extra costs.