Packing light for travel makes your trip simpler. It also saves you money, especially given the fees now levied by most airlines on your check-in baggage. 

But if you must check in luggage, whether you’re transporting wine or just a big bottle of shampoo (big as in, more than 3.5 ounces), factor in these fees when you’re comparing ticket prices for flights in the U.S.

Delta (Stock Quote: DAL), American Airlines (Stock Quote: AMR), United Airlines (Stock Quote: UAUA) and Continental Airlines (Stock Quote: CAL) generally charge $15 for your first checked bag and $25 for your second if you’re flying coach. (And they’ll charge more if your luggage is over a certain weight, usually 50 pounds.)

Then there's US Airways (Stock Quote: LCC), which is raising fees on checked bags.  If you booked your flight before April 23, you’ll have to pay $15, $25 and $100 for your first, second and third through ninth bags. But for flights booked on or after that date, you’ll have to pay an extra $5 on top of that for your first ($20) and second ($30) bags, unless you pay online.

If you have more than two bags to check, American Airlines may charge you more than you paid for your seat. You’ll have to pay $100 per bag for the third, fourth and fifth bags and $200 each thereafter. 

Exceptions to the Rules
They may not be cheap, but there are some ways to avoid those fees.  If you’re springing for first class or business class tickets on Delta, you aren’t subject to check-in bag fees. You’re also exempt if you’re a SkyMiles or WorldPerks Elite member or if you paid full fare (as in, not from a discount site) for a coach ticket.

International travelers flying with American Airlines can check in two bags for no charge, but you’ll have to contact the airline if you plan on checking more. On domestic flights, the checked-bag fees don't apply to business class ticket holders, AAdvantage Executive Platinum, Platinum or Gold members, customers with full-fare coach tickets and members of the military.  United and Continental have similar exemptions.

JetBlue (Stock Quote: JBLU) still lets all customers check in one bag free of charge, and only charges $20 for a second bag.  If you have more than two pieces of luggage to check, you’ll have to pay $75 for each extra bag.