Carry-On Luggage

• Most airlines restrict carry-on bags to less than 40 lbs. In addition, bags must fit in an overhead bin or under the seat, which means they should not exceed 45 to 55 inches.
  
  

Check-In Luggage

• All airlines have size and weight restrictions regarding check-in luggage. Fees are usually incurred for checking in more than two bags or for having bags that weigh more than 50 lbs. and/or exceed 62 linear inches.
  
  

Excess Baggage Fees

• Excess baggage fees are charged for bags in excess of the customary two. Airlines such as Delta, which charge $15 for the first and $25 for the second checked bag, charge $125 for the fourth and $200 for the fifth, regardless of weight. (Prices current as of October 2009.)
  
  

Overweight Bag Fees

• Bags over 50 lbs. can occur additional fees. Delta charges $90 for bags between 50 to 70 lbs. for domestic flights and $150 for international flights; bags between 71 to 100 lbs. occur additional fees.
  
  

Unacceptable Weight

• Bags in excess of 100 lbs. are typically not accommodated on flights.
  
  

Exception

• Airlines like United allow baggage fee waivers for active duty members of the military traveling with no more than two bags. In addition, those who belong to customer reward programs and who have accumulated a certain amount of frequent flyer miles can sometimes have fees waived.