Linear inches is the sum of your luggage's length, width, and height

To find the linear inches of a bag, add together its length, width, and height in inches. That single number is what airlines use to decide whether your luggage fits their size limits. A bag measuring 22 inches long, 14 inches wide, and 9 inches tall has 45 linear inches (22 + 14 + 9 = 45). Most airlines allow carry-on bags up to 45 linear inches and checked bags up to 62 linear inches, though some budget carriers are stricter.

The measurement matters because airlines enforce it at the gate. If your bag exceeds the limit, you may be forced to check it, pay a fee, or leave it behind. Knowing your bag's linear inches before you pack saves you from that surprise at the counter.

Key Takeaways

  • Linear inches is length plus width plus height, measured in inches, and airlines use this number to enforce carry-on and checked bag size limits.
  • Most airlines allow 45 linear inches for carry-on and 62 for checked bags, but budget carriers often set lower limits, so check your airline's policy before packing.
  • Measure the bag's exterior dimensions at its widest points, including wheels, handles, and any protruding parts.
  • If your bag is close to the limit, pack light and avoid overstuffing, because a bulging bag may not fit even if the linear inches are technically under the threshold.

How to measure your bag correctly

Use a soft measuring tape or a ruler and measure the bag when it is empty and sitting upright on a flat surface. Measure the length from top to bottom, the width from side to side, and the depth from front to back. Always measure at the widest point of each dimension — if your bag has wheels, include them in the height measurement. If the handle extends above the bag, measure to the top of the handle.

Round up to the nearest whole inch. If your length is 21.5 inches, count it as 22. Airlines measure the same way, and rounding up protects you from being told your bag is oversized at check-in.

What counts toward the measurement

Wheels, handles, pockets, and any other part of the bag that sticks out all count. A rolling carry-on with a retractable handle and spinner wheels must include those in the height measurement. Soft-sided bags that bulge when packed may measure larger than their stated dimensions — if the bag expands, measure it in its expanded state.

Straps, compression panels, and external pockets do not add to the linear inches unless they make the bag wider or taller overall. A bag with a small front pocket still measures from the widest point of the bag itself, not from the pocket.

Carry-on versus checked bag limits

Most full-service airlines (United, American, Delta, Southwest) allow carry-on bags up to 45 linear inches and one personal item (purse, laptop bag, small backpack) with no size limit. Checked bags usually go up to 62 linear inches. Budget carriers like Spirit and Frontier often cap carry-on at 40 linear inches and charge for checked bags that exceed 62 linear inches.

Some airlines measure differently — a few use length × width × height instead of adding them, or they set limits on individual dimensions rather than the total. Always check your specific airline's website before packing. The policy is usually listed under "baggage" or "checked baggage" in their help section.

Bags that are close to the limit

If your bag measures 44 or 45 linear inches, it is at the edge of the carry-on threshold. Pack it light and avoid overstuffing. A bag that is technically 45 inches but bulges when full may not fit in the overhead bin or under the seat, and gate agents have the final say on whether a bag fits. Soft-sided bags are safer near the limit because they compress slightly, while hard-sided bags cannot flex.

If you are unsure, bring the bag to the airport early and test it against the sizing frame at the ticket counter. Most airlines have a metal or plastic frame near check-in that shows the exact dimensions allowed. If your bag does not fit the frame, you will know before you reach the gate.

How to find your bag's linear inches if you do not have it yet

Most luggage manufacturers list the linear inches on the product page or in the specifications. Look for "linear inches," "total inches," or "overall dimensions" — some sites list length, width, and depth separately, and you add them yourself. If the bag is sold in a store, ask a staff member or measure a display model.

Online retailers like Amazon, Walmart, and luggage-specific sites usually include the dimensions in the product details. If you are buying from a brand's own website, the specifications are almost always in the "Details" or "Specs" section below the product description.

What happens if your bag exceeds the limit

If your carry-on is oversized, the airline will gate-check it — send it to the cargo hold with checked bags — at no charge on most carriers. You will retrieve it at your destination. On some budget airlines, you may be charged a checked bag fee instead. If your checked bag exceeds the limit, you typically pay an oversize fee, usually between $50 and $100 depending on the airline.

The best strategy is to measure before you pack. If your bag is over the limit, use a smaller bag, pack less, or ship items ahead. Shipping a box of clothes ahead of time costs less than an oversize baggage fee and gives you more packing flexibility.

Frequently Asked Questions

Do I measure the bag with or without the handle extended?

Measure with the handle extended if it is a rolling bag. The handle is part of the bag's overall size, and airlines measure the bag as it would be stored. If the handle retracts completely inside the bag, you can measure without it extended, but most rolling bags have handles that stick up even when retracted, so include those.

What if my bag has a front pocket that adds an inch?

Measure from the widest point of the bag itself, not from the pocket. A small front pocket does not add to the linear inches unless it makes the entire bag deeper. If the pocket is flush with the bag's surface, it does not count.

Can I compress my soft-sided bag to fit the size limit?

Yes, soft-sided bags can compress, and airlines expect that. If your bag measures 46 inches when full but compresses to 44 inches when you remove some items, it will fit. Hard-sided bags cannot compress, so they must be under the limit when packed.

Do different airlines have different linear inch limits?

Yes. Most major airlines allow 45 linear inches for carry-on and 62 for checked bags, but budget carriers often allow 40 linear inches for carry-on. International airlines may have different limits. Check your specific airline's baggage policy on their website before you pack.

Is linear inches the same as cubic inches?

No. Linear inches is length plus width plus height. Cubic inches is length times width times height. Airlines use linear inches, not cubic inches. A bag that is 22 × 14 × 9 inches has 45 linear inches but 2,772 cubic inches.