Packing for TSA's New 3D CT Scanners: The Carry-On Checklist You Need Before You Fly

The Transportation Security Administration's rollout of 3D CT scanners changes two things for carry-on travelers: your bag must physically fit through a smaller scanner opening, and you may no longer need to unpack the items you used to. TSA spokesperson Daniel Velez told reporters the new machines measure 24.5 inches wide by 16.5 inches high, and the agency cautions that bags that don't fit may have to be checked with the airline instead of carried on. Here's what that means for how you pack—and a checklist to run before you leave home.

Understanding TSA's New 3D CT Scanners

TSA has been installing computed tomography (CT) scanners at security checkpoints across the country, replacing older X-ray equipment. In a press release, the agency described the core advance: an X-ray camera spins around items, shooting hundreds of images to build a three-dimensional view of a bag's contents.

"This new technology creates such a clear image of a bag's contents that the system can automatically detect explosives and other threat items," TSA said. Those automatic threat-detection algorithms mean officers can often inspect a bag digitally rather than opening it, which the agency expects to speed up the process for everyone in line.

Key Differences: 2D X-ray vs. 3D CT Screening

The practical difference for you is what stays in the bag. In lanes using the older generation of checkpoint equipment, passengers became used to unpacking before screening. As AFAR reported, "passengers no longer have to fish their laptop or bag of travel-size liquids out of their carry-on luggage before sending it through the X-ray machine" at airports with the CT units.

TSA's own guidance, quoted by Caroline Morse Teel at Smarter Travel, is explicit: "The CT units provide TSA officers the ability to review a 3D image of passengers' bags and reduce the need to search the bag's contents. Passengers screened in security lanes with CT units do not need to remove their travel-size liquids bag or electronics."

That last part carries a condition. The liquids that can stay packed are travel-size liquids adhering to the 3-1-1 rule—so the standard limits still apply. And the efficiency only holds if your bag fits the machine and doesn't trigger secondary screening.

New Carry-On Size Limitations for 3D Scanners

Here's the catch travelers are hearing about: the CT scanners have a smaller opening than the machines they replace. "This design is necessary to accommodate the advanced imaging technology and ensure optimal performance," Velez explained. The Independent's reporting notes that bags exceeding airline size requirements "may have trouble entering the machine," and TSA warns that bags that don't fit won't be allowed on the plane—travelers will have to check them with the airline, a real cost if you packed to avoid baggage claim.

Before you panic, do the math. The scanner opening is 24.5 inches wide and 16.5 inches high. Most airlines allow carry-ons up to 22" x 14" x 9", and per reporting by Simple Flying cited in coverage of the rollout, a standard bag of that size fits the new scanners. Problems arise, as LiveNOW from FOX reported, when passengers show up with bags larger than the airline limit—or expandable bags pushed past it. Velez also noted that TSA officers are on hand to assist travelers with larger items or special needs.

Your 3D CT Scanner Carry-On Checklist

Run this before you leave for the airport. It synthesizes the scanner's physical constraints and bin requirement with TSA's standing rules into a single do's-and-don'ts diagnostic—each item traces back to either the agency's stated dimensions, Velez's tips, or TSA's CT-lane guidance.

Pre-travel diagnostic for carry-ons headed into a 3D CT scanner lane
Checkpoint	Do	Don't
Bag size	Measure your bag against your airline's size guidelines (commonly 22" x 14" x 9"), which fit the 24.5" W x 16.5" H scanner opening.	Don't assume an expandable bag will pass—expanded bags that push past the airline limit may not enter the machine and could be checked instead.
Packing strategy	Keep laptops, tablets and electronics packed; keep travel-size liquids in your 3-1-1 liquids bag inside the carry-on.	Don't overstuff outer compartments; Velez specifically flags this as a fit risk.
Checkpoint procedure	Place your entire carry-on flat inside a checkpoint bin—every item scanned by a CT machine must go in a bin, unlike older belts.	Don't send a rollaboard directly down the belt as you might have before.
Unknowns	Ask a TSA officer if you're unsure your bag will fit; officers assist with larger items and special needs.	Don't rely on this article for prohibited-item questions—check TSA's official "What Can I Bring?" list for specific items.

Note two boundaries on this advice: it covers carry-on luggage only, not checked baggage, and it isn't a definitive prohibited-items guide. Not every airport or lane has the CT units yet, so if you're unsure whether your itinerary includes one, confirm with your airline or check the checkpoint signage when you arrive.

At the Checkpoint: What to Expect

If your airport has converted a lane to CT, expect a quieter experience with fewer bins of loose electronics. Your laptop and travel-size liquids stay in the bag; your whole bag goes flat into a bin and through the scanner. Officers reviewing the 3D image can rotate the view from any angle, reducing the need to open and hand-search bags when the image is clear.

If the automatic threat detection or an officer's review flags something, your bag may still be pulled for secondary screening—and that's where the time savings evaporate. That's the trade-off in a single sentence: CT lanes are faster when bags fit and screen cleanly, and slower for anyone whose overstuffed or oversized bag jams the process.

Smooth Sailing Through Security: Your Next Steps

Travelers should adapt their carry-on packing strategy to align with the new TSA 3D CT scanner requirements, prioritizing bag size compliance and understanding which items can remain inside. Practically, that means measuring your bag against your airline's limit before your next trip, resisting the expandable zipper, and leaving laptops and your 3-1-1 liquids bag packed when you reach a CT lane.

The measure of success is simple: a traveler passes through a 3D CT scanner lane without their carry-on bag being pulled for secondary screening or being forced to check it. If your standard-size bag clears on your first CT-lane trip, you've packed for the new system correctly—and you can stop pre-unpacking at security entirely.