Measure length, width, and depth with a tape measure or ruler

Luggage size is measured by adding the length, width, and depth of the bag in inches or centimeters. Place your suitcase on a flat surface, then measure from the furthest point on each side — the longest part of the bag lengthwise, the widest part side to side, and the deepest part from front to back. Write down all three numbers, then add them together. That total is your bag's linear dimension, which is what airlines and luggage standards use.

Use a soft measuring tape if you have one, since it conforms to curved corners. A rigid ruler or metal tape measure works too, but you may need to account for rounded edges by measuring the straightest path across. Measure twice to avoid mistakes — getting the dimension wrong could mean your bag is rejected at check-in or costs you an oversize fee.

If your bag has wheels, handles, or straps that stick out, do not include them in your measurement. Measure only the main body of the luggage. Wheels and handles are considered part of the bag's footprint by most airlines, but the measurement itself focuses on the packed dimensions.

Key Takeaways

  • Luggage size is the sum of length plus width plus depth, measured in inches or centimeters on a flat surface.
  • Measure the longest point lengthwise, the widest point side to side, and the deepest point front to back, then add all three numbers together.
  • Most airlines set carry-on limits between 45 and 56 linear inches, and checked bag limits between 62 and 80 linear inches, though these vary by carrier.
  • A soft measuring tape gives the most accurate result, but a ruler or metal tape works if you measure the straightest path across the bag.
  • Wheels, handles, and straps that protrude are part of the bag's overall size for airline purposes, even though you measure only the main body.

Why airlines measure this way instead of weight alone

Airlines use linear dimensions because they need to know whether your bag will fit in the overhead bin or under the seat in front of you. A bag can be light but still too large to stow. A 22-inch carry-on suitcase might weigh only 5 pounds but take up more space than a heavier duffel bag with softer sides. Dimension limits protect the airline's ability to load planes efficiently and may support every passenger gets their bag on board.

Checked bags are measured the same way because ground handlers and baggage systems have size constraints. A bag that is too long or too deep will jam in the conveyor system or not fit in the cargo hold alongside other luggage. Weight limits exist separately — your bag can be within the size limit but still too heavy — because the aircraft has weight restrictions for safety and fuel efficiency.

Standard carry-on and checked bag dimensions by airline

Most major U.S. airlines allow carry-on bags up to 22 inches long, 14 inches wide, and 9 inches deep — a total of 45 linear inches. Some airlines, including Southwest and Spirit, use the same limit. Others, like American and United, allow slightly larger bags: 22 by 14 by 9 inches is still common, but a few carriers permit up to 24 by 16 by 10 inches (50 linear inches). Budget airlines often have stricter limits, sometimes as low as 40 linear inches.

Checked bags typically max out at 62 linear inches for standard luggage, though some airlines allow up to 80 linear inches for oversized bags — which then cost extra. A typical large checked suitcase measures 28 inches long, 20 inches wide, and 12 inches deep, totaling 60 linear inches. If your bag measures 65 linear inches, you will likely pay an oversize fee, usually between $50 and $100 depending on the airline.

Always check your specific airline's website before you travel, because limits vary and change. Some airlines measure differently — a few still use weight as the primary limit for checked bags, with size as a secondary restriction. Knowing your airline's policy before you pack saves you from surprises at the airport.

How to measure bags with soft sides or expandable compartments

Soft-sided luggage and bags with expandable sections should be measured in their normal packed state, not fully expanded. If your suitcase has a zipper that expands the depth by 2 inches, measure it as if that zipper is closed. Airlines assume you will pack the bag to its intended size, not stretch it beyond design limits. If you measure with the expansion open, you are measuring a bag that does not actually exist in normal use.

For duffel bags and soft luggage without rigid frames, place the bag on a flat surface and let it settle naturally. Do not compress it or fluff it up artificially. Measure the outline as it sits. This gives you the realistic dimension the bag will occupy in an overhead bin or cargo hold.

What to do if your bag is slightly over the limit

If your bag measures 46 linear inches and the limit is 45, you are over by one inch. Some airlines enforce limits strictly and will charge you or refuse the bag. Others have a small grace margin, usually 1 to 2 inches, especially for carry-on bags. You cannot count on this — it depends on the airline and the agent checking you in.

Your safest option is to measure before you travel and choose a bag that comes in under the limit with room to spare. If you already own a bag that is slightly over, contact your airline directly and ask whether they have flexibility. Some will let it through; others will not. Do not assume you can argue your way through at the gate — the agent has no authority to override size limits, and you may end up paying a fee or checking a carry-on bag you planned to keep with you.

Measuring bags you are buying online

When you shop for luggage online, the product description lists dimensions. These are measured the same way — length by width by depth. Add them up to get the linear dimension before you buy. Many online retailers also state the linear dimension directly, which saves you the math. If the listing does not include dimensions, look for customer reviews that mention whether the bag fits airline carry-on limits, or check the manufacturer's website.

Be aware that some retailers list interior dimensions (the space inside the bag) rather than exterior dimensions (the actual size of the bag as it sits). Interior measurements are smaller and will not match what an airline measures. Look for the word "exterior" or "overall" to make sure you are getting the right number. If you are unsure, email the seller before you buy.

Frequently Asked Questions

Do I measure my luggage with or without the wheels?

Measure only the main body of the bag. Wheels, handles, and straps that stick out are not included in the measurement itself, though airlines do consider them part of the bag's overall footprint for stowage purposes. Measure the straightest path across the bag's frame.

What if my bag is soft-sided and changes shape when I pack it?

Measure the bag in its normal packed state, not compressed or expanded. If your bag has an expandable zipper, measure it closed. Airlines assume you will pack the bag to its intended size, and that is what they measure at check-in.

Can I measure my bag in centimeters instead of inches?

Yes. Most airlines publish limits in both inches and centimeters. Measure whichever way is easier for you, then convert if needed. One inch equals 2.54 centimeters. A 45-inch limit is roughly 114 centimeters.

What happens if my bag is over the size limit at the airport?

The airline may charge you an oversize fee (usually $50 to $100), require you to check the bag instead of carrying it on, or refuse the bag entirely. Policies vary by airline. Measuring before you travel prevents this problem.

Do budget airlines measure luggage differently?

Budget airlines often have stricter size limits than major carriers — sometimes as low as 40 linear inches for carry-on bags. Always check your specific airline's policy on their website, because limits vary widely and change over time.