Best Carry-On Travel Backpack for Easy, Organized Packing

As a former serial overpacker, it blew my mind when a few of my friends came to visit me when I was studying abroad in London — with no checked bags, just matching REI 40L backpacks as their carry-ons. And on my next big international trip, I decided to try it out myself. I borrowed one of their backpacks… and I was convinced!

The next thing I knew, I was buying an REI Trail 40 backpack of my own — and it’s been my go-to carry-on bag for almost 10 years.

My Favorite Carry-On Backpack: REI Trail 40

Benefits of Traveling With a Backpack as Your Carry-On

While I spent three years as a traveling technology consultant in my early 20s and became an expert at packing for week-long work trips in just a carry-on roller bag, I’ve been team #backpack for my leisure trips ever since I borrowed that first REI bag. When you’re moving from city to city — whether you’re in Asia, Europe, or somewhere else — you just can’t beat the convenience of being hands-free.

You don’t have to be that annoying tourist who is loudly dragging their roller bag on Italian cobblestones at 5 a.m. on the way to the train station. You don’t have to stop and find the hidden elevator in all of Tokyo’s metro stations that seem to be nothing but stairs. (Not even escalators!)

And most of the time, when flight attendants start asking people to gate-check their roller bags, they won’t even look twice at you — because you have a backpack, and they either assume it’s small enough, or they assume they can make it fit in the overhead bins.

Benefits of the REI Trail 40 As Your Carry-On Travel Backpack

There are a few reason I specifically love the REI Trail 40. And probably the biggest benefit (in my opinion) is just how many pockets it has! With two interior pockets, an interior pouch, two front exterior pockets, three exterior side pockets/pouches, a bottom exterior pouch, and a pocket in each of the hip belt straps… packing is simple when it’s so easy to compartmentalize all your things.

My personal favorite pockets are probably the front mesh pocket (perfect for stashing my liquids in their little clear bag for easy access when going through airport security) as well as the exterior side pockets (perfect for stowing a pair of shoes without getting everything else dirty).

I also really like the loops on the outside, which are great for tying on yet another pair of shoes, and I’ve never once had airline staff give me a hard time about that.

Basically, this bag is perfect for when you’re trying to maximize your packing, but do it efficiently! The interior steel frame helps maintain your bag’s shape and redistribute the weight to be more comfortable, along with the hip belt. And besides all that,  this backpack also holds up pretty well against rain — though it also comes with a rain cover (that I lost years ago).

Who Is an REI Trail 40 Backpack a Great Fit For?

The REI Trail 40 could be a great carry-on travel backpack for you if you’re a traveler who…

• likes to pack efficiently but with plenty of space for everything you need
• prefers to be hands-free while moving through airports, metro stations, and cobblestone city streets
• wants to lower their risk of having to gate-check their bag on flights
• is able to carry moderate weight on your back on travel days
• needs a durable bag that can stand up to weather and other general travel-induced wear and tear
• likes to pack odd-shaped items like multiple pairs of shoes
• wants a reliable backpack that could last them a decade or more

On the other hand, an REI Trail 40 backpack (or any carry-on travel backpack) might not be your best bet if you…

• prefer to check your carry-on when possible (backpacks offer less protection for your items than hard-shell suitcases)
• have neck/back problems and prefer not to carry heavy weight on your back
• are a business traveler who needs your clothes to stay folded neatly

Comparing REI Bags as Carry-On Travel Backpacks

Besides the REI Trail 40, REI also offers other 40L and 35L bag options that you could use as carry-on travel backpacks. Here’s how they stack up so you can see which would be the best fit for you.

Three Trips Where I’ve Packed the REI Trail 40 as My Carry-On Travel Backpack

This is my REI Trail 40 that I use as my carry-on travel backpack! Always stuffed to the brim 😉

1. Two weeks in Spain; October 2016

When I say I was a serial overpacker, I mean it: I would take a 50lb (23 kg) checked bag to Europe every time… until this trip when I decided to give the carry-on-only life a try. Knowing that I was going to be traveling through five or six cities during my two-week visit to Spain, that heavy checked bag just would not be an option. I loved not having to wait for my checked bag at the airport, worry about it getting lost, drag it around with me, have to take the elevator in the metro stations, roll it on cobblestones… I was hooked!

2. Eight weeks in Europe; August-September 2023

I had never packed in just a carry-on for such a long trip before… but we visited Spain, Croatia, Slovenia, Italy, Germany, and Portugal over the course of eight weeks, and it sounded like a hassle to check a bag with all the flights we’d be taking. Not to mention, expensive! It was a challenge because we encountered a wide variety of weather conditions during those two months, and we also had our engagement photos taken in Porto during the trip, so we had to make sure we had at least one nice outfit with us the whole time. Space/vacuum bags were my real MVP! That picture of my bag above is from this trip.

3. Six weeks in Asia; August-September 2025

For our honeymoon to Japan, Taiwan, and South Korea, we knew we’d be on the move constantly for six weeks, and a checked bag would only slow us down. Once again, I relied on vacuum bags for my clothes. And somehow, even with buying a thousand souvenirs for our family throughout the course of the trip, we were able to get everything back home without a problem. I swear the pockets on this bag are infinite!

My Packing List: REI Trail 40 Carry-On Travel Backpack

(Note: This list includes what I bring in my small everyday backpack that I use as my personal item on long trips when I still have to work.)

Clothing

• 6 tops (or 3 sweaters)
• 2 pairs of pants
• 1 pair of leggings
• 1 pair of shorts
• 1 dress
• 1 sweater or hoodie
• 1 jacket
• 1 raincoat
• 2 sports bras
• 2 regular bras
• 10 pairs of underwear
• 1 pair of pajamas
• 4 pairs of socks
• 1 pair of sandals
• 1 pair of sneakers

Electronics

• Laptop & charger
• Nintendo Switch
• Kindle
• Bose headphones
• Phone charger & cord
• Portable charger
• Dual-voltage hairdryer and foldable diffuser

Personal care

• Contact lenses and travel contact solution
• Glasses and case
• Toothbrush and toothpaste
• 4 travel-sized skin & hair care products
• 2 washcloths
• Turbie twist microfiber hair towel
• Small makeup bag
• Makeup remover wipes
• Solid shampoo & conditioner bars
• Small jewelry case
• Lume deodorant
• Silk pillow case & silk hair bonnet
• Medication + prescriptions

Miscellaneous

• Foldable travel umbrella
• Daily planner and pencil pouch
• Water bottle

Frequently Asked Questions About REI backpacks

Does the REI Trail 40 fit under airplane seats?

No, the REI Trail 40 bag is 40L, which is too big to fit underneath the seat in front of you. If you’re looking to travel in a personal item bag only, consider the Cabin Zero Classic Cabin Bag.

Does the REI Trail 40 fit in the overhead bin?

The REI Trail 40 has fit in the overhead bin of every plane I’ve ever traveled on — but there’s a chance it may not fit if you’re on a really small plane. In that case, you may have to turn your bag sideways, and that also means you’ll want to try to be one of the first ones on the plane before the overhead space starts filling up.

Is the REI Trail 40 durable enough for long-term travel?

Yes, the REI Trail 40 is very durable. I’ve personally had mine for nearly 10 years, and it’s been on countless week-long trips as well as trips that have lasted several months. It only shows minor wear and tear but there have been zero impacts to functionality.

Can it be used for hiking + travel?

The REI Trail 40 was designed as a hiking backpack, and its secondary use is a travel backpack. It’s equipped with plenty of features that make it great for both hiking and travel, so it should be easy to adapt it to your needs at any given time.

Does it count as a personal item?

This particular bag is too big to count as a personal item, so you’ll need to use it as your carry-on backpack.

Do airlines ever gate-check backpacks?

Airlines do sometimes gate-check people’s carry-on bags, but in my experience it’s more likely to happen for roller bags. However, there’s always a chance your carry-on backpack could be gate-checked if they run out of room on the plane. For that reason, it’s important to always keep any valuables and/or medications with you at all times — don’t put them in your carry-on.

Is a 40L backpack big enough for trips to Europe or Asia?

40L has been plenty of room for me on trips of several months to Europe and Asia — it just depends on how you pack. I typically use space or vacuum bags to help me save room, and I know packing cubes are another popular option. If you’re usually able to travel with just a carry-on roller bag, a 40L backpack would likely be enough space for you.

Is the REI Trail 40 backpack worth it?

I definitely think the REI Trail 40 is worth it! When I bought it, I was about to move to Spain to work as an English teacher (and make no money) so I was worried about the price, but all these years later, I can definitively say it was worth the money. It’s lasted me nearly a decade so far and shows no sign of wearing out anytime soon. And I’ve become so used to traveling with it, that packing is now a breeze because I know where everything should go. I highly recommend this bag to any travelers who are looking for a reliable carry-on travel backpack!

This site contains affiliate links. I may receive a commission for purchases made through these links at no additional cost to you.