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US airlines charged almost $5 billion in baggage fees last year—here's how to avoid them

A traveler waits at the airport.

The U.S. Department of Transportation's annual airline baggage fee report found that domestic carriers collected nearly $5 billion in baggage fees last year, up from $4.5 billion in 2017 and $1.1 billion a decade ago.

American Airlines brought in the most money from baggage fees in 2018, collecting $1.2 billion. It was followed by United, which collected $889 million.

So, how can you check a bag for free on a U.S. airline? With the exception of Southwest, which still allows customers two checked bags for free so long as they follow certain size restrictions, you'll typically need to join a carrier's rewards program, use a particular credit card or buy a premium ticket.

Here are your options.

Sign up for frequent flyer programs

Frequent flyer programs are one way to potentially secure free checked bags. Certain members of AAdvantage, American's rewards program, for example, can check as many as three bags for free, depending on membership status.

You can also receive a free checked bag once you reach Delta Medallion Status, and there are multiple tiers within the medallion program that offer different perks and additional free checked bags.

The avocado toast, house buying dilemma — illustrated by avocados
The avocado toast, house buying dilemma — illustrated by avocados

Not every frequent flyer program is created equal, though. Especially if the airline charges for membership, you'll want to run the numbers before signing up to ensure that membership is worth the potential cost. For example, Spirit's $9 fare club starts at $59.95 per year but doesn't offer members free checked bags, but less expensive baggage fees in addition to potentially cheaper ticket prices.

That said, if frequent flyer programs are free, there's no reason not to sign up. Here's a list of the best frequent flyer programs of 2018.

Buy a premium ticket

Perhaps the easiest way to score a free checked bag is to upgrade your seat. For example, all first class, Delta Premium Select and Delta One passengers receive two free checked bags when flying Delta within the U.S., as do premium economy and business class passengers on American Airlines.

If you're looking to save money, though, this isn't the most prudent choice: Your premium or business-class ticket can cost hundreds of dollars more than a basic economy seat, depending on the flight and the carrier. Given that your first checked bag on a domestic flight will cost you between $18 and $65 on most airlines, you'd likely be spending way more money for that seat upgrade.

That said, flying business- or first-class offers other perks in addition to a free checked bag, including more leg room, food and beverage service and other amenities, so while it's not an option for everyone, you could consider whether it feels worth spending more to get more.

Use the right credit card

More and more airlines are offering branded credit cards, and those cards can come with perks that include free checked bag. Certain Delta SkyMiles card holders, for example, get one free checked bag each for themselves and up to eight travel companions when they book with their card, while travelers with a United Explorer card get a free checked bag for themselves and one companion. The JetBlue Plus Card allows cardholders and up to three travel companions on the same reservation to check a bag for free.

Weigh the full pros and cons of signing up for an airline's reward card first, though. One important consideration: The annual fee. These cards will cost you $127 a year on average. If you don't check a bag often, you might not come ahead when the annual fee is taken into account.

Interest rates are also typically higher on rewards cards than on ordinary cards, so if you carry a balance you'll end up paying more over time.

5 of the best travel rewards credit cards for young people
5 of the best travel rewards credit cards for young people

The number of free bags you're offered varies depending on the airline. That's important, because if you're traveling with your family, for example, paying for your tickets with the airline's credit card won't necessarily get each of you a free checked bag, Matt Schulz, chief industry analyst for CompareCards, tells CNBC Make It.

Familiarize yourself with each card's restrictions and limitations, he says. Cards with high annual fees are likely to get you more free bags.

If you're loyal to and take regular trips on a particular airline, it can make sense to apply for the company's credit card. But if you tend to shop around for the best flight deal, you may want a travel card with the fewest restrictions instead. That could be a card like the Chase Sapphire Reserve: It has a $450 annual fee but comes with a $300 annual travel credit, which can be put toward baggage fees.

"Flexibility is often the key to getting the most out of your credit card rewards, and it is no different when it comes to checked bag fees," says Schulz. "Many high-end travel cards come with annual travel credits that can cover your checked bag fees regardless of what airline you fly on."

Don't miss: 6 tips to travel cheaper — from a 30-year-old who saved $60,000 on vacations

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These are the best ways to travel the world for super cheap
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