Anyone who’s flown enough knows the real test doesn’t happen at security; it happens at the gate. That’s where bags get judged: how they carry themselves, how much trouble they promise to cause once the overhead bins are full. The rules may shift an inch here or there, but the message is universal: carry-ons are under scrutiny.
In an era of tighter carry-on enforcement, understanding what actually fits has become just as important as knowing your seat number.
And then it happens. You’re in line, boarding pass out, feeling unstoppable — when your eyes drift a few feet to the left. That’s when you see it — the metal sizing frame, ominously parked in the corner, is pretending it’s just another piece of airport furniture — no warning signs. Just quietly waiting to ruin someone’s confidence.
United, Delta, American — pick your airline, the ritual is the same. A bag slides in cleanly, and you’re waved through. A bag hesitates, needs a nudge, needs a strategic tilt — maybe 45°? — and now you’re replaying your entire packing process while watching your carry-on get tagged and sent off with the rolling luggage you were determined to avoid.
We’ve gathered information and rounded up the dimensions of all our most popular travel bags to hopefully shed some light on major airlines' carry-on policies — which TOM BIHN bags make the cut, and give you some packing tips to ensure your bag fits.
The Real Dimensions of the Baggage Sizer
Under current FAA standards, the Federal Aviation Administration, a carry-on’s total dimensions can’t exceed 45 linear inches, or the total of a bag’s height, width, and depth, including wheels and handles. Anything larger should be checked before boarding.
The good news is these standards are pretty universal among most major airlines, including but not limited to United, Delta, and American Airlines.
United, Delta, and American Airlines published limits for carry-ons are 9” (d) x 14” (w) x 22” (h), or 23cm x 35cm x 56cm. The metal frame at the gate usually has a little breathing room built in — enough to account for handles, wheels, and the reality that not every bag is a perfect rectangle.
Personal items must fit under the seat in front of you. While there’s not a universal personal item size limit, some airlines require items that do not exceed 9” (d) x 10” (w) x 17” (h), or 22cm x 25cm x 43cm. But unlike carry-on sizing restrictions, personal item size limits are a bit more relaxed.
This is great news for those traveling with TOM BIHN bags. Many of them either fit in these dimensions outright or can be made to fit with a bit of careful packing. The trickier part isn’t whether a single bag fits — it’s figuring out which combination of carry-on and personal item will clear the gate with minimal drama.
The list below will show which bags fit easily and which push the limit of the published and/or actual baggage sizer dimensions. Just remember: 45 linear inches or 9” (d) x 14” (w) x 22” (h) for carry-ons and around 9” (d) x 10” (w) x 17” (h) for personal items, and you’re good to go!
Carry-on Safe Travel Bags
Carry-on Safe Backpacks
Upper Limit Carry-ons:
A little over the 9” x 14” x 22” or 45 linear inches published limit, but can work if you pack smart.
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Medium Yeoman Duffel: 22.8” (w) x 9.4” (h) x 13.8” (d)
Personal item Safe:
Upper Limit Personal Items:
A little over the 9” x 10” x 17” limit, but can work if you pack smart.
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Synik 30: 20.0” (h) x 13.4” (w) x 8.0-10.8” (d)
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Synik 26: 18.0” x (h) x 13.2” (w) x 10.8” (d)
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Synapse 25: 20” (h) x 13.4” (w) x 9.1” (d)
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Synapse 19: 16” (h) x 11.4” (w) x 7.9” (d)
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Smart Alec 2.0: 15.7" (h) x 12.2" (w) x 9.4" (d)
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Marathon Messenger: 11” (h) x 15.5” (w) x 10.2” (d)
Packing Your Bag so it Fits the Sizer
You’ll notice that some personal item bags are a little taller or wider than the published — or even the actual sizer dimensions. That’s not necessarily a problem, and there’s no need to worry. First, gate agents aren’t sitting around with measuring tapes waiting to measure your bag, but rather they're looking for items that grossly exceed the dimensions (so don’t try to pass off your Aeronaut 45 as your personal item). Second, gate agents typically look to gate check rolling luggage first since those types of baggage are generally the most onerous to fit in the overhead bins. Finally, the soft sides of our bags make it easy to stuff them into the sizer, so you may be able to use a TOM BIHN bag that is technically too large to be a personal item (for example, members of our team and forum use the Synik 30 as a personal item when they fly, despite it being a few inches over the limit).
The trick, as always, is not to overpack. Those soft sides that let you cram your gear into awkward corners of overhead bins can also betray you — they expand if you fill them to the brim. A bag that fits perfectly at home can suddenly refuse to slip into the sizer if you pack like you’re preparing for a month-long adventure instead of a long weekend.
Packing smart often comes down to simple tricks. To avoid overstuffing your bag, you might try employing packing cubes and making sure that they are filled evenly to the edges, since extra volume in the middle of the bag often causes it to develop a barrel-like shape. The slimmer your bag looks, the less likely you’ll be subjected to the sizer.
When you’re carrying a backpack, try to utilize as much of the vertical space as possible so that everything doesn’t migrate to the bottom (once again, the goal here is to reduce bulk). Some forum members have found success using their Side Effects as internal backpack pouches, which can then double as handy in-flight compartments using Swivel Double Carabiners.
New to TOM BIHN bags? Check our Forum for tips on packing smart while keeping your travel essentials close at hand. And of course, if you have questions about what fits in the Baggage Sizer — or in a specific bag — we’re just one email or phone call away!
Bart - January 17, 2026
What a GREAT article! No nonsense, just got to the facts, thank you.