If you have ever stood at the gate hoping your bag will pass the airline sizer, you are not alone. A lot of travelers still mix up a personal item and a carry on, and that confusion can get expensive fast.
The basic difference is simple. A personal item is the smaller bag that must fit under the seat in front of you. A carry on is the larger bag that usually goes in the overhead bin. The problem is that airline size rules are not identical.
The short version
Personal item: If you want one size that gives you a safer margin across several major airlines, aim for 17 x 13 x 8 inches or smaller.
Carry on: A bag around 22 x 14 x 9 inches works within the published limits for American, Delta, and JetBlue.
Before you fly: Check both the size rule and what your fare actually includes. A bag can be the correct size and still cost extra on some fares.
Personal Item: What Counts?
A personal item is the smaller bag you keep with you and place under the seat in front of you. Common examples include a purse, small backpack, laptop bag, tote, or briefcase.
The name of the bag matters less than its actual size. A backpack can be a personal item if it fits the airline limit and fits under the seat. An overstuffed tote can become a problem if it no longer fits the sizer.
Carry On: What Counts?
A carry on is the larger cabin bag. It is usually a small rolling suitcase, duffel, or larger backpack that goes in the overhead bin. Airlines generally count handles, wheels, and attachments when measuring the bag.
Airline Rules for 2026
Rules checked August 27, 2026. Always verify again before your trip because baggage policies can change.
American Airlines
Personal item: 18 x 14 x 8 inches
Carry on: 22 x 14 x 9 inches
American allows one personal item and one carry on when both meet the requirements.
Delta Air Lines
Personal item: Must be similar in size to a purse, small backpack, briefcase, or laptop bag and fit under the seat.
Carry on: 22 x 14 x 9 inches
Delta allows one carry on and one personal item free of charge.
JetBlue
Personal item: 17 x 13 x 8 inches
Carry on: 22 x 14 x 9 inches
JetBlue currently allows one carry on and one personal item on all fares.
Southwest
Personal item: Must fit under the seat in front of you.
Carry on: 24 x 16 x 10 inches
Southwest allows one carry on and one personal item onboard.
Frontier
Personal item: 18 x 14 x 8 inches and up to 35 pounds
Carry on: 24 x 16 x 10 inches and up to 35 pounds
One personal item is included with every ticket. Carry on bags may cost extra depending on the fare, bundle, or status.
Spirit Airlines Update
Spirit Airlines began an orderly wind down of operations on May 2, 2026, and states that all flights were cancelled. Old Spirit baggage charts can still appear in search results, so this guide does not treat Spirit as an active airline option.
Best Size Across Airlines
If you want a personal item that is easier to use across several airlines, 17 x 13 x 8 inches or smaller is a practical target. That fits within JetBlue’s stricter published limit and also falls within the larger 18 x 14 x 8 limits used by American and Frontier.
For a carry on, 22 x 14 x 9 inches is a strong cross airline target because it matches the published limits for American, Delta, and JetBlue. Southwest and Frontier allow larger carry on dimensions, but buying to their larger size can make the bag less flexible on other airlines.
What actually fits in a personal item?
- A change of clothes
- Travel size toiletries
- Phone and charger
- Tablet or small laptop
- Passport and travel documents
- Snacks
- Small makeup or personal care pouch
For a short trip, a well packed personal item can hold more than people expect. The biggest mistake is stuffing a soft bag until it becomes larger than the airline sizer.
What actually fits in a carry on?
- Several outfits
- One or two pairs of shoes
- A light jacket
- Electronics
- Your liquids bag
- Trip essentials for a weekend or longer stay
The low cost airline trap
Do not assume that a correctly sized carry on is automatically included in the ticket price. Frontier includes one personal item with every ticket, but a carry on may need to be purchased separately unless your fare, bundle, or status includes it.
Before booking, ask two separate questions: Does my bag fit the size limit? and Does my fare include that bag?
Remember the TSA liquid rule
For standard liquids, gels, and aerosols in cabin baggage, containers are limited to 3.4 ounces or 100 milliliters at the TSA checkpoint. Medically necessary liquids have different rules and may be allowed in larger amounts when declared for screening.
How to avoid a surprise bag fee
- Measure the bag before travel.
- Include wheels, handles, and straps in your measurement.
- Check the exact fare you purchased.
- Do not overstuff a soft bag that needs to fit in a sizer.
- Buy baggage before arriving at the airport when the airline charges less online.
- Check again if your itinerary includes more than one airline.
Our simple recommendation
If you want the least complicated setup, choose a personal item no larger than 17 x 13 x 8 inches and a carry on around 22 x 14 x 9 inches. Then verify your fare before every trip.
That does not guarantee every aircraft or route will handle baggage the same way, but it gives you a practical margin across several major U.S. airlines.
Official sources checked
Rules checked August 27, 2026 from American Airlines, Delta Air Lines, JetBlue, Southwest, Frontier, FAA, and Spirit’s operations update.
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