TSA will be much stricter on carry-on bag size. What to know

There are new scanners being used for carry-on luggage at a lot of airport security lanes across the country. There’s good news and bad news.

The good news: New TSA scanners make flying safer

The good news is you’ll be much safer flying because these new 3-D machines allow TSA officers to digitally rotate and zoom inside the bag. They’ll have a far better look at what is going into the passenger compartment. This is opposed to the old scanners, which flattened bags into a single image on their screens.

These scanners are now in over 250 security checkpoints, but they’re soon greatly expanding across the country.

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a plane on the runway

The bad news: Oversized carry-ons may be stopped before you reach your gate

That’s where the bad news comes in.

It isn't that the carry-on size rules are changing. It’s that they’re now going to be far more strictly enforced. That’s because the new scanners have a smaller opening to fit a bag through at only 24.5 inches wide and 16.5 inches high.

If you already strictly monitor yourself to the allowed carry-on sizes, you’ll be fine. The problem is that those size restrictions routinely went ignored at security and often at the gate. Even if you didn’t get challenged at security with the older, bigger scanners but did at the gate, the gate agent could gate-check your carry-on.

Now? The TSA agent dealing with a smaller opening on the new scanners has the authority to send you all the way back to the ticket counter and have you wait in line again to check your bag. And they probably will if it won't fit in the new, tighter scanners.

So you’ve been warned. The days of overstuffing that carry-on to the point it looks pregnant and getting it into the plane’s overhead luggage compartment — or even having it conveniently gate-checked — will soon be over.

Check your airline’s carry-on size before heading to the airport

So if you don’t want to be sent all the way back to the ticket counter, make sure your carry-on complies fully with your particular airline’s policy. For example, United’s limit is 22 by 14 by 9. It’s easy to go over that, but you probably will have a harder time getting away with it now.

So check with your airline, make sure your bag fits its size policy and don’t overstuff it. Good luck!