Know before you go.

Everything You Need to Know About Every Airline’s Baggage Fees
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As all the major airlines — from United to Delta to American — introduce new “basic economy” fares, everything you thought was included in your flight price suddenly isn't. Basic fares provide only the most basic service of getting you from point A to B, while a seat assignment, onboard amenities, itinerary changes or cancelations, and even room for your carry-on now cost extra.

While travelers have the choice to skip the basic fare and pay for a more inclusive ticket, in this new era of à la carte flying it is more important than ever for fliers to know where their dollars are going. For example, knowing about how much you'd pay in fees for baggage can inform your flight purchasing decision when you see the prices for basic, regular or even premium economy.

For many of us, the simple question is: How much? While separate pricing can help passengers save money if they're willing to forego any extras, the fees can add up quickly, and suddenly your cheap flight will be anything but.

When it comes to baggage, each airline is a little different. Southwest, for example, is the only major U.S. domestic carrier that offers two free checked bags with every ticket. Meanwhile, a basic economy fare on American or United doesn't even include overhead bin space. If you pack light — really light — a cheaper fare on the latter two could be the better option. If you'll be bringing luggage, however, a slightly more expensive fare on the former could turn out cheaper.

Consider this your cheat sheet to everything you should know about airline baggage fees.

When it comes to overhead bin real estate, low-cost carriers are giving you better bang for your buck. While most of the bigger airlines, like United and Delta, adhere to a standard 45 linear inches (that’s 22” long, by 14” inches wide, by 9” deep), companies like Southwest and Alaska have loosened their idea of what travelers are allowed to carry on board. With Alaska, that limit increases to 51 linear inches, and on Spirit, Southwest and Frontier, it’s 50 inches.

Other changes are afoot: In 2015, JetBlue introduced its new three-tier system, in which customers can specify what kind of fare they want based on what their travel needs are. There are three choices: “Blue” (the cheapest, with no checked bags included), “Blue Plus” (one checked bag) and “Blue Flex” (two checked bags). Don’t let bags be the only factor in your decision, though — the different fares also mean different service levels.

One last tip: If you are checking a bag, familiarize yourself with the airline’s size and weight limit first. And don't forget to weigh your bag before you leave the house. The last thing you want is to show up at the airport and have to pay $75 or more for an overweight or oversize bag. The cost of airfare is high enough.