(NEXSTAR) — Suddenly, the airline passengers who wear seven pairs of pants and four sweaters to avoid extra fees don’t seem quite as silly.

Several major U.S. airlines have raised fees for checked baggage over the last few months, starting with Alaska Airlines in January before JetBlue, American Airlines and United followed suit. The additional fees imposed by these carriers don’t amount to too much more — a $5 increase per bag, in many cases — but the current fee increases may not end with United, one travel expert claimed.

“Airlines tend to move in herds, so when Alaska recently announced they would be upping their bag fee to $35, there was little doubt other airlines would soon follow,” said Scott Keyes, founder of the travel site Going, in a statement to the Associated Press.

In 2008, American Airlines became the first U.S. carrier to charge for checked bags as part of a cost-cutting move that prompted one airline consultant to remark that passengers might eventually be required to “pay by the pound” for their tickets, The New York Times reported at the time.

While U.S. airlines haven’t yet resorted to weighing passengers, fees for bags have only risen. In 2008, American’s fee for the first checked bag was only $15, but that amount has more than doubled in the years since.

How much can passengers expect to pay?

Alaska Airlines, in January, raised its checked-baggage fee for most economy customers by $5 across the board, from $30 to $35 for the first bag and $40 to $45 for the second.

JetBlue, too, raised fees for the first and second checked bags to $45 and $60, respectively, but offers a $10 discount (making the final cost $35 or $50, respectively) for those who pay online at least 24 hours before departure.

American Airlines and United operate on similar models, with discounts for passengers who pre-pay 24 hours before their flights. For American, the new checked-bag fee is $40 for the first piece of luggage — or $35 if prepaid — and $45 for a second piece. United is also charging $40 for the first piece — but $35 if prepaid — and $50 for a second piece, which can be discounted to $45 if prepaid online.

Fees will often vary for many international trips, most airlines note. Overweight bags are also subject to additional charges too, though American will be lowering its fees for some overweight or oversize bags as of April.

Why are prices rising now?

In statements provided to Nexstar, three of the four airlines that raised bag fees in 2024 (Alaska, American and JetBlue) blamed current operating costs for the increased fees.

“As we navigate rising operating costs — including high fuel prices — we occasionally need to adjust our fee structure to maintain a high level of excellence in the service we provide,” a representative for Alaska Airlines wrote, while an American Airlines spokesperson added that the carrier’s new fee structure came about during a routine evaluation of “ancillary offerings.”

JetBlue further claimed that its business has been “unprofitable since COVID.”

Bag fees, meanwhile, drive plenty of revenue for airlines, according to 2022 data from the U.S. Department of Transportation. That year — the last whole year for which data is available — U.S. airlines earned nearly $6.8 billion combined just from baggage fees. The available data from the first nine months of 2023 shows the industry on track to beat that figure, according to Reuters.

Can you avoid the fees?

Aside from pre-paying for your checked baggage early, most airlines offer several opportunities for travelers to check their bags (or some of them) completely free of additional charges. Members of the military are often allowed a certain number of free checked bags, as are select higher-status members of the carriers’ frequent flyer programs. Checked bags might also be free when purchased with certain credit cards (like those offered on the airlines’ websites).

Don’t meet any of the above criteria? There’s always the option to fly with Southwest, the one major U.S. airline that doesn’t charge fees for a passenger’s first or second checked bags.

Everyone else, though, might have to get creative to evade the latest additional bag fees.

“I have tested out stuffing my clothes into a neck pillow, into a slightly too big bra, and in a duty-free bag,” one traveler previously told Nexstar of her attempts to skirt fees by essentially wearing her luggage on her person. “All have worked, but I think the main takeaway at this point is that staff at the gate are busy. And as long as you’re not pushing the limits too far, they just want to get you on the plane quickly!”