Luggage Allowances for Infants

Free Items

• The airlines generally won't charge you for bringing several big-ticket items to the gate to check there, including your stroller-- unless it's a model that rivals a small car in size -- or your car seat. For most domestic airlines, you get to check one or the other -- not both. If your stroller is very large or doesn't fold easily, you might be told to leave it at the check-in counter, meaning that you'll have to carry your baby through the airport. Strollers, like other carry-ons, must go through security. If you have any concerns about the size of your stroller, call the airline ahead of time to ask about their policies.

When Baby Flies Free

• If you're taking your baby on board as a lap child -- meaning you have to hold him the entire flight -- he doesn't get to bring a suitcase with him, unless you pay for it out-of-pocket. You can still bring his car seat or stroller with you and gate-check it. You can pay an additional fee to bring an extra suitcase for yourself, but your bag fees will add up. American Airlines, for example, charges $35 in 2013 for a second checked bag in addition to the $25 for the first checked bag, each way, or a total of $120 round-trip in baggage fees.

When Baby Pays

• If you're buying your baby a seat, depending on your ticket, he can check the same amount of free luggage you can -- one suitcase weighing up to 50 pounds, in most cases, for domestic flights. His suitcase can be just as large as yours, even if he was just born last month and doesn't have much of a wardrobe yet.

Carry-On Luggage

• When you bring your baby with you, you can also bring his diaper bag and enough liquid refreshment and food in jars for him to get through the flight. There's no set limit on the amount of formula or pumped breast milk you can cart with you, according to the Transportation Security Administration, but don't overdo it. If you're realistic about what you'll need for a several-hour flight, you should have no trouble getting your supplies through security.