If you’re stopped before boarding, it can come as a costly surprise: Your “personal item” is too big to bring on the plane.

For Sergio Diaz, it was a projector he used for his keynote presentations. “It’s not much bigger than a laptop,” said Diaz, a professional speaker from Los Angeles. But on a recent flight from Los Angeles to New York, an American Airlines gate agent declared that the projector was too large to fit under his seat and that he had to pay $50 to check it.

Airlines are usually clear about what is — and what isn’t — a personal item. For example, American defines it as a purse or small handbag that must fit under the seat in front of you. The bag’s dimensions should not exceed 18 by 14 by 8 inches.

Diaz was disappointed that the airline forced him to check his projector. “I thought it would be fine,” he says.

But increasingly, it is not fine. Airlines are cracking down on carry-on luggage.

American Airlines, for instance, generated a record $7.42 per passenger in baggage revenue in 2021, raking in $1.22 billion systemwide, according to a recent study by IdeaWorks and CarTrawler. I’ve been hearing from many passengers who say they have experienced tougher enforcement of carry-on and checked baggage rules, which would be consistent with the revenue gains.

Other airlines, notably the ultra-low-cost carriers, have built their business around a la carte fees for items such as carry-on luggage. And the type of luggage they’re scrutinizing the most, according to passengers, is the personal item.

Airlines have different, and sometimes confusing, definitions of a personal item.

Part of the reason for the discrepancies across air carriers is that they fly different types of aircraft. Some seats are smaller, and some have plenty of room for a larger personal item below the seats or in the overhead bin. The only major airline that can indicate how much room is under its seats is Southwest Airlines, because it flies only Boeing 737s.

But another reason for the sometimes vague definitions may be that it empowers the airline to stop you from boarding an aircraft with your bag — and force you to pay a fee. And in 2023, experts say, airlines are redoubling their efforts to collect more luggage fees.

“The definition of a personal item is subject to interpretation,” says Danielle Belyeu, a travel adviser with Catching the Sun, a travel agency in Summerville, S.C.

She says airline crews have recently focused their enforcement efforts on shopping bags. On one recent flight, an attendant scolded her for carrying too many.

“I had to step aside and consolidate by throwing away the bag and stuffing items into my two allowable bags,” she recalls.

Checking a bag vs. carrying on is the great debate of airline travel

Is your backpack or laptop bag too big to fly free? That depends.

The best strategy is to ensure your personal item conforms to the smallest standard (Southwest’s 16.25 by 13.5 by 8 inches). Don’t try to bring anything that defies the norms of the personal item. In other words, stick to a backpack or purse.

That strategy may work, but it’s not guaranteed. If the overhead bins fill up or if the flight is full, attendants may ask passengers to start gate-checking luggage. And they may insist that you surrender an item that you consider a “personal” item.

I remember one reader who had to give up a small handbag on a flight from Bermuda to Philadelphia that contained her car keys, house keys and other valuables. The flight attendants were trying to make room for a first-class passenger’s luggage. The airline lost her bag.

If you’re in business class or first class, you’re probably fine. In the unlikely event that there’s no room in the overhead bin, a flight attendant will usually find space elsewhere.

There’s also a slight difference between “premium” economy class and regular economy. Because the seats are farther apart in the premium cabin, you’re more likely to have more space under your seat or in the overhead compartment.

Embrace overpacking: The case against carry-ons

The hardest part of flying with a personal item is getting it onboard. If your backpack is a little overpacked, you’ll have to deal with at least three gatekeepers: the check-in agent, the gate agent and a flight attendant. A black backpack that blends with dark clothes will be less conspicuous. A shopping bag filled with snacks, not so much.

Checking in online (or at an automated kiosk) instead of the ticket counter will get you past the first obstacle. Boarding with a large group of other passengers can slide you past the second one. And boarding early if possible, when there’s still enough overhead bin space, can get you home.

Most personal items don’t require any special handling or care. They’re for carrying your laptop computer, your tablet computer or your keys. Some airlines won’t even let you check electronics, because they break easily.

In addition to personal devices and keys, you should keep medications, mobility devices or medical equipment close at all times. Mahmood Khan, a professor of hospitality and tourism at Virginia Tech, says airlines have to be respectful of these items, which means you could keep a bag from getting gate-checked if you explain what’s inside.

“If a gate agent asks you to gate-check your carry-on bag, tell the agent that you have personal items that need to stay in your possession, such as cameras, electronics or medication,” he says. “Agents can make exceptions when necessary.”

We asked: What happens if TSA finds weed in my bag?

You might be able to get a personal item — even one that’s too large — on a flight operated by one of the major airlines. But when it comes to the discount or ultra-low-cost airlines, it’s becoming much more difficult.

At least that’s the experience of passengers such as Katy Kassian, a small-business owner from Max, Neb. She was recently flying from Denver back to Sacramento with her granddaughter, carrying a small purse. The Frontier Airlines flight attendants allowed her on the plane with her bag, “but at least a full quarter of the people boarding the plane had to gate-check their bags at great expense,” she said. “They were miffed.”

Patricia Hall, an IT worker from Leesburg, Fla., was one of the passengers who had to surrender a personal item on a recent Frontier flight from Syracuse, N.Y., to Orlando. A Frontier flight attendant stopped her and her husband at the gate and said their tote bags were too big to be “personal” items.

“The agent told me we would be charged $10 per bag,” she remembers.

Instead, Frontier charged them $89 each. The airline insisted that was the correct amount.

Frontier strictly limits the size of its personal items to 14 by 18 by 8 inches, a measurement that includes handles, wheels and straps. “Items larger than the allowed dimensions are subject to an additional charge,” it warns.

The airline discloses these fees in a roundabout way on its site. (You have to look up your flight to get a quote for your luggage fee.)

“Whether a bag fits under the seat is not the determining factor as to whether it qualifies as a personal item,” Frontier spokeswoman Jennifer de la Cruz said in an email. “It must fit the required dimensions and fit into the sizer in the gate area.”

Which brings us to the best and only way to avoid getting dinged for a personal item: Make sure your bag fits the airline’s dimensions for personal items, or carry your essential belongings in your jacket, vest or money belt.

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