How airlines and luggage makers measure your bag
Luggage is measured three ways: linear inches (or centimeters), which add up the length, width, and depth; actual weight in pounds or kilograms; and sometimes volume in liters. Airlines use linear inches most often because it limits both size and density at once. A bag measuring 22 inches long, 14 inches wide, and 9 inches deep totals 45 linear inches. That single number is what most carry-on policies refer to when they say "22 x 14 x 9" or "under 45 inches."
Weight limits are separate. A bag can be within the linear-inch limit but still too heavy to bring aboard or check. Most airlines allow 50 pounds for checked luggage and have no official weight limit for carry-on, though they do require you to lift it into the overhead bin yourself. Some budget airlines charge by weight instead of by piece, so a 35-pound bag might cost more than a 25-pound one even if both fit the size rules.
Luggage makers print dimensions on a tag or label, usually on the back or bottom of the bag. They measure the bag when it is empty and sitting flat, not when it is packed or standing upright. The order is almost always length × width × depth, though some brands list it as height × width × depth instead. Check the label on your specific bag to be sure which dimension is which.
Key Takeaways
- Linear inches are the sum of length plus width plus depth; a bag labeled 22 x 14 x 9 totals 45 linear inches.
- Airlines measure carry-on and checked bags differently—carry-on has a size limit (usually 22 x 14 x 9 inches), while checked bags have both a size and weight limit (usually 50 pounds).
- The dimensions printed on your luggage tag are measured when the bag is empty and flat, not when packed or standing up.
- Weight and size are measured separately; a bag can pass the size test but fail the weight limit, or vice versa.
Carry-on size limits and how they work
Most major airlines allow carry-on bags up to 22 inches long, 14 inches wide, and 9 inches deep—totaling 45 linear inches. Some airlines are stricter: Southwest allows 24 x 16 x 10 inches (50 linear inches), while budget carriers like Spirit or Frontier may go as low as 21 x 13 x 8 inches (42 linear inches). A few airlines, including some international carriers, use centimeters instead: 55 x 40 x 20 centimeters is roughly equivalent to 22 x 16 x 8 inches.
The airline measures your bag at the gate if it looks oversized. They use a metal frame called a sizer that sits at the end of the jetway. If your bag fits through the frame, it is within limits. If it does not, you will be asked to check it or remove items. Soft-sided bags (made of fabric) can compress slightly and sometimes squeeze through when a hard-sided bag of the same dimensions would not, which is why some travelers choose them for carry-on.
Wheels, handles, and pockets count toward the measurement. A bag with a protruding handle or a front pocket that sticks out will measure larger than the same bag without those features. If you are close to the limit, measure your bag with the handle extended and any pockets fully expanded to get the true size.
Checked baggage size and weight rules
Checked bags have both a size limit and a weight limit. Most airlines allow checked bags up to 62 linear inches (the sum of length, width, and depth) and 50 pounds. Some airlines are more generous—United, for example, allows up to 62 inches and 70 pounds on some routes—while others are stricter. Budget airlines often charge extra for any checked bag, or charge by weight rather than by piece.
The 50-pound limit is where most travelers run into trouble. A large suitcase can easily hold 60 or 70 pounds of clothing and shoes, especially if you are packing for a long trip. Weigh your bag at home before you go to the airport. Most luggage stores and many grocery stores have scales. If your bag is over the limit, remove items or split them between two bags.
If your checked bag exceeds the weight limit, the airline will charge an overweight fee—usually $50 to $100 for the first 10 pounds over, and more for anything heavier. Some airlines charge per pound once you go over. A few airlines allow a second checked bag at no extra charge if the first one is under the weight limit, so it may be cheaper to check two lighter bags than to pay an overweight fee on one heavy one.
How to measure your luggage correctly
Use a soft measuring tape or a ruler, not your eye. Measure the outside of the bag, not the inside. Start at one corner and measure straight across to the opposite corner—do not measure around curves or along the seams. For length, measure from the bottom to the top of the bag (or front to back, depending on how the bag sits). For width, measure side to side. For depth, measure from front to back (or top to bottom).
Measure with the bag empty and standing upright or lying flat, whichever way you plan to pack it. If you always pack your bag and then lay it flat to roll it into the overhead bin, measure it that way. If you stand it upright in the closet, measure it standing. The bag's shape can change slightly depending on how it is positioned, and you want to know the largest dimension it will be.
Write down the three numbers and add them together to get the linear inches. Compare that total to your airline's carry-on or checked-bag limit. If you are within the limit, you are good. If you are over, you will need a smaller bag or a different airline.
Understanding weight limits and how to stay under them
Carry-on bags have no official weight limit on most airlines, but you must be able to lift the bag into the overhead bin yourself. If a flight attendant thinks your bag is too heavy, they can ask you to check it. In practice, most carry-on bags weigh between 15 and 25 pounds, and anything over 30 pounds will draw attention.
Checked bags have a hard weight limit, usually 50 pounds. Anything over that incurs a fee. Some airlines charge a flat fee for bags between 50 and 70 pounds, then a much higher fee for bags over 70 pounds. A few airlines will not accept checked bags over 100 pounds at all, no matter how much you pay.
To stay under the weight limit, pack light. Wear your heaviest shoes and jacket on the plane instead of packing them. Leave behind items you can buy at your destination. Use compression bags to reduce the volume of clothing, though this does not reduce weight. If you are traveling with multiple people, distribute items across multiple bags rather than overstuffing one.
Soft-sided versus hard-sided bags and how they measure
Hard-sided bags (made of plastic or polycarbonate) hold their shape and measure the same whether they are empty or full. A 22 x 14 x 9 inch hard-sided bag will always measure 22 x 14 x 9 inches. Soft-sided bags (made of fabric or leather) can compress and expand, so the same bag might measure 22 x 14 x 9 inches when empty but 22 x 14 x 10 inches when packed.
This matters at the gate. A soft-sided bag that is slightly over the size limit might still fit through the sizer if it compresses. A hard-sided bag that is over the limit will not. If you are close to your airline's carry-on limit and want the best chance of getting your bag aboard, a soft-sided bag gives you a little wiggle room.
However, soft-sided bags are easier to damage. They offer less protection for fragile items, and the fabric can tear or wear through. Hard-sided bags protect contents better but are heavier and take up more space in your closet. Choose based on what you are packing and how much you value durability.
What happens if your luggage is oversized or overweight
If your carry-on is oversized, the airline will ask you to check it at the gate. You will not pay a fee if it is your first checked bag and your ticket includes a free checked bag, but you will lose access to your luggage until you land. If you have already paid for a carry-on-only ticket, you may be charged a checked-bag fee.
If your checked bag is overweight, you will pay an overweight fee at the ticket counter before you check it. The fee varies by airline and by how much over the limit you are. Most airlines charge $50 for the first 10 pounds over 50 pounds, then $100 or more for anything heavier. Some charge per pound. Ask the airline what their specific fee structure is before you check in.
If your bag is significantly oversized—for example, a 70-inch bag when the limit is 62 inches—the airline may refuse to check it at all. In that case, you will need to either remove items, repack into a smaller bag, or ship the bag to your destination separately. This is rare, but it happens with oversized items like skis or musical instruments that do not fit standard luggage.
Frequently Asked Questions
Do wheels and handles count toward the luggage measurement?
Yes. Wheels, handles, and any pockets or protrusions are part of the bag's dimensions. Measure with the handle extended and any front pockets fully expanded to get the true size. This is especially important for carry-on bags, where a protruding handle can push you over the airline's limit.
Can I pack my bag fuller if it is soft-sided?
Soft-sided bags can compress slightly, which may help you fit through a gate sizer if you are close to the limit. However, overpacking can damage the bag's seams and zippers. Pack to the bag's intended capacity, not beyond it, even if the fabric stretches.
What is the difference between linear inches and volume?
Linear inches are the sum of length plus width plus depth—a single number that airlines use to set size limits. Volume is the total space inside the bag, measured in liters or cubic inches. Airlines use linear inches because it is simpler to enforce and prevents both oversized and overly dense bags.
Do all airlines measure luggage the same way?
No. Most major airlines use similar limits (22 x 14 x 9 for carry-on, 62 inches and 50 pounds for checked), but budget airlines and international carriers vary. Always check your specific airline's website before you pack. Some airlines measure in centimeters instead of inches.
Can I check a bag that is over the size limit but under the weight limit?
It depends on the airline. Most airlines enforce both size and weight limits for checked bags. A bag that is oversized but light may still be rejected. Some airlines will accept it if there is space in the cargo hold, but you should not count on it. Contact your airline before you travel if your bag is oversized.