The Cheapest Flight from Chicago May Depend on the Bag You Bring

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You find a flight at a great price, choose your dates and start picturing the trip. Then the booking page asks about bags. Suddenly, that bargain fare does not look quite so cheap.
For a family of four flying Southwest this fall, checking one standard suitcase per person could add $360 to a round trip. That is four bags at $45 each way, assuming no traveler has a fare, credit card or status benefit that waives the charge.
The number under “fare” is only the starting point. Chicago travelers choosing among flights from O’Hare and Midway may face very different rules for personal items, overhead bags and checked luggage. Some tickets inc,Budget Travelpassenger count the same.
Suppose Airline A charges $180 round trip plus $50 each way for an overhead bag. Airline B charges $240 and includes the bag. The totals for a traveler who needs overhead space are $280 on Airline A and $240 on Airline B. If everything fits under the seat, Airline A remains cheaper.
Those prices are examples, not live fare quotes. The calculation is what matters. Two fares cannot be compared fairly when they include different things.
Families should also ask whether every person needs a paid bag. Two children may be able to share one checked suitcase. A couple might check one larger case instead of buying two overhead bags. Put a change of clothes and other immediate necessities in each traveler’s permitted personal item in case the shared bag is delayed.
Add any seats you plan to buy. Include the cost of reaching O’Hare or Midway with the luggage in tow. If the return uses another airline or fare type, calculate it separately. The outbound bag rules do not carry over to a different ticket.

Start with what the ticket includes

A carry-on is a kind of bag. Whether your ticket includes one is a different question.
United’s domestic Basic Economy rules generally allow one personal item, while a larger carry-on must be checked. There are exceptions for eligible loyalty members and cardholders, and certain international routes include a carry-on. United’s standard Economy fare includes one carry-on and one personal item. If you need the overhead bin, compare those two fares after adding the bag cost to Basic Economy.
American allows one personal item and one carry-on within its published size limits. The personal item can measure up to 18 by 14 by 8 inches. The carry-on limit is 22 by 14 by 9 inches, including wheels and handles.
Frontier includes one personal item with every ticket. An overhead bag and checked luggage may cost extra or come with a bundle. The airline says the price depends on the travel date and when the bag is purchased. Avelo also includes a personal item but generally charges for an overhead bag. Active-duty military travelers receive an exception.
Do not assume a seat selection includes a bag. On some booking screens, seats and luggage are separate purchases. Check the benefits listed beside the exact fare you are considering.

Measure the bag after packing it

That suitcase may have worked perfectly on your last flight. A different airline can still reject it at the next gate.
These are selected overhead-bag limits, shown in inches with the longest measurement first. The table tells you what may fit. It does not tell you whether your ticket includes the bag.

The difference is easy to miss. A case measuring 24 by 16 by 10 inches meets Southwest’s published limit but is too large for American, United and Avelo. That matters on a trip using one airline outbound and another on the return.
Measure the bag when it is full, including wheels, handles and anything sticking out. If it expands, measure it. Check the personal item too. United lists a limit of 17 by 10 by 9 inches, while Avelo lists 17 by 13 by 9. A backpack that looks small can still be too wide.
Shopping for a new case? Ignore a product label that simply says “carry-on.” Compare the full exterior measurements with every airline on the itinerary. A luggage company cannot decide whether your fare includes overhead space.

Price the same trip three ways

Run the numbers with only personal items, with the overhead bags you need and with shared checked luggage. Keep the dates and passenger count the same.
Suppose Airline A charges $180 round trip plus $50 each way for an overhead bag. Airline B charges $240 and includes the bag. The totals for a traveler who needs overhead space are $280 on Airline A and $240 on Airline B. If everything fits under the seat, Airline A remains cheaper.
Those prices are examples, not live fare quotes. The calculation is what matters. Two fares cannot be compared fairly when they include different things.
Families should also ask whether every person needs a paid bag. Two children may be able to share one checked suitcase. A couple might check one larger case instead of buying two overhead bags. Put a change of clothes and other immediate necessities in each traveler’s permitted personal item in case the shared bag is delayed.
Add any seats you plan to buy. Include the cost of reaching O’Hare or Midway with the luggage in tow. If the return uses another airline or fare type, calculate it separately. The outbound bag rules do not carry over to a different ticket.

Watch the weight of a shared suitcase

Combining everyone’s clothes into one case can cut bag fees. It can also create an overweight charge.
Frontier’s standard checked-bag allowance is 40 pounds. A bag weighing 41 to 50 pounds carries a published $75 surcharge. Its Business bundle includes two checked bags weighing up to 50 pounds each. Avelo’s standard checked-bag limit is 50 pounds. It lists a $100 charge above that weight and does not accept bags over 70 pounds.
Imagine the family suitcase weighs 44 pounds. It is within Avelo’s standard limit but over Frontier’s standard allowance. The same packing plan can therefore produce a different bill depending on the airline and bundle.
Weigh the suitcase when it is fully packed. Remember that the case itself counts. Compression bags reduce the space clothes take up, but the weight stays the same. Leave a few pounds free if you expect to bring home gifts or purchases.

Check bundles before buying bags separately

Frontier’s Economy bundle includes a carry-on and a standard seat. Premium and Business bundles add other benefits. Compare the bundle with the total cost of the separate items you actually want. A benefit has no financial value if you would not otherwise buy it.
When you pay also matters. Frontier says its lowest bag prices are offered during booking. Prices rise at the airport and are highest at the gate. Avelo also says buying baggage during the initial reservation costs less than paying at the airport.
If you already know you need a bag, record its price while comparing flights. “I’ll decide later” can be expensive. Save the confirmation showing which bags, seats and other services you purchased.

Check where the smaller airline lands

A low fare to a familiar city name may use an unfamiliar airport.
Avelo’s 2026 Chicago route announcements connected O’Hare with Concord-Padgett Regional Airport, serving the Charlotte area, and Wilmington Airport in Delaware, serving the Philadelphia region. The airline’s airport directory lists its Chicago service at O’Hare.
That means a flight advertised for the Charlotte area may not land at Charlotte Douglas. A flight serving the Philadelphia region may not arrive at Philadelphia International. Search the airport code and price the trip from that airport to your hotel, home or meeting.
Check the schedule as carefully as the map. A smaller airline may fly a route on fewer days, leaving fewer alternatives if a flight changes. At the Chicago end, compare how much time and money it takes to reach O’Hare or Midway from home. A cheaper ticket can lose its advantage when the airport is farther from where you need to be.

Prepare for a gate check

Paying for an overhead bag does not guarantee that it will remain in the cabin. United says bags may be checked at the gate when the bins fill, and overhead space is limited on United Express flights.
Keep medication, identification, keys and valuables in the personal item that stays with you. Move them before boarding begins. Digging through a suitcase after an agent has tagged it slows the line and makes it easier to leave something behind.
Power banks and spare lithium batteries require special care. The Federal Aviation Administration says they must stay in the cabin. If a carry-on is sent to the hold at the gate or beside the aircraft, remove those batteries first and protect their terminals from contact with metal. Airlines may set stricter limits.
Ask where the bag will be returned before handing it over. United says most gate-checked bags go to baggage claim at the final destination. On United Express, a bag may instead come back on the jet bridge. Photograph the bag tag and keep the receipt.

File a report when a checked bag is late

When a suitcase fails to arrive, there are two money issues: the fee paid to check it and the cost of necessary replacement items.
The U.S. Department of Transportation says a checked-bag fee is refundable when the bag is significantly delayed, subject to stated exceptions. For a domestic flight, the threshold is 12 hours after arrival. You must first file a mishandled-baggage report. Once the delay qualifies, the fee refund should be automatic.
Airlines must also compensate passengers for reasonable, verifiable expenses caused by delayed baggage, within the applicable liability limits. Keep receipts for necessary purchases and file the claim promptly. The baggage-fee refund and the expense claim cover different losses.
The best time to do this math is before the booking page starts counting down. Pack enough to know which bags you need. Measure and weigh them. Then compare the round-trip fare with the seats, luggage and airport transportation you will actually pay for. That is the price of the trip.