A low airfare rarely covers everything you need for a trip. Bags, seat choices, earlier boarding and even help at the airport often carry their own charges, and airlines do not add them to the price you see first. Nine of those fees follow, with current prices from Delta, American and Frontier. Check the airline’s fee page before you book so the total matches your actual trip.
First Checked Bag
Checking one standard suitcase can add a charge in each direction. Delta’s current domestic baggage price is $45 for the first standard bag and $55 for the second. Those rates apply to eligible Delta Main and Delta Comfort customers without a waiver. Credit card, elite-status and military benefits can change the price.
Carry-On Bag
An overhead-bin suitcase is not included with every low fare. Frontier says its basic fare leaves out a carry-on bag. One personal item is included. The carrier also says bag prices rise closer to departure. The highest price is at the gate. Compare baggage costs before calling a bare fare the cheapest choice.
Advance Seat Selection
Buying a ticket does not always include a free seat choice. American lists Preferred Seats from $4 to $139 per flight in Main Cabin. Main Cabin Extra runs from $20 to $280. Prices vary by flight. Status or a higher fare can include the benefit.
Priority Boarding
Earlier boarding can be a separate product rather than a ticket feature. American prices its Priority option from $9 to $74 each way. The amount depends on the trip. Priority can improve a traveler’s place in line. It does not replace a carry-on allowance or promise overhead space.
Overweight or Oversize Baggage
A paid checked bag can still cost more if it crosses the airline’s limits. American’s excess-baggage chart lists a $100 overweight fee for a 53- to 70-pound bag on many U.S. and Canada trips. That fee sits on top of the checked-bag charge. If a bag is both large and heavy, American applies the higher of those two extra fees.
Same-Day Confirmed Change
Many fares no longer have standard change fees. Moving to another flight on the travel date can still cost money. American’s same-day confirmed change starts at $60 on eligible U.S., Puerto Rico and U.S. Virgin Islands trips. Free standby may be available. It depends on open seats and does not promise a place.
Unaccompanied Minor Service
A child’s airfare may not include the care required for solo travel. American charges a $150 unaccompanied-minor fee each way, plus tax. The service is required for children ages 5 through 14 traveling alone. It is optional for ages 15 through 17. One fee can cover qualifying siblings on the same flight.
Pet in the Cabin
A small pet’s carrier usually counts as the traveler’s carry-on. The animal still has a separate charge. Delta’s in-cabin pet fee is $150 each way for tickets issued on or after April 8, 2025. That price covers eligible travel within the United States, Canada, Puerto Rico and the U.S. Virgin Islands. Route and kennel rules also apply.
Airport Agent Assistance
In-person help may cost extra when free self-service is available. Frontier’s Airport Agent Assistance covers tasks such as check-in or printing a boarding pass. Its fee page lists a charge of up to $25 per traveler, per direction. An exemption applies when a passenger cannot use self-service because of a disability.
Price the Trip, Not Just the Fare
Federal airfare rules draw a useful line between what a fare must include and what a traveler chooses to add. The advertised price must cover the cost of the air transportation, while optional services require the traveler’s choice before airlines add their fees. That makes the checkout total only one part of comparison shopping, so add every needed extra for every traveler and both directions before comparing the complete trip instead of the opening fare.