How this instrument works
Linear inches is the simplest way an airline can size a bag without doing multiplication: measure the length, width and height of the packed suitcase — including wheels, handles and any external pockets that bulge out — and add the three numbers together. A bag that measures 24 by 18 by 12 inches, for instance, comes to 54 linear inches, comfortably inside most carriers' standard checked-bag allowance.
Most major airlines cap standard checked baggage at 158 centimeters, or 62 inches, of combined length, width and height before an oversize fee applies — a threshold set as an industry-wide guideline by the International Air Transport Association and adopted by most global carriers, though individual airlines, routes and fare classes can vary the exact number. Go a few inches over that line and the fee is often steep enough to have been worth checking before you packed, not after.
Linear inches is not the same measurement as the dimensional weight that parcel carriers like UPS or FedEx use to price shipments — dimensional weight multiplies length by width by height and divides the result by a size factor, producing a weight-equivalent number rather than a simple sum. Airlines add three numbers together; parcel carriers multiply and divide. Confusing the two is an easy way to misjudge whether a bag or box will trigger an extra charge.
- Measure your packed bag's length, width and height in inches, including wheels and any external pockets, and enter each in its field.
- Read Total linear inches — the sum of all three dimensions — the moment you finish entering the third number.
- Compare the result against your airline's stated limit, typically 62 linear inches for standard checked baggage.
- Over the limit? Try removing exterior pouches or swapping to a lower-profile bag — even one inch under the threshold can avoid an oversize fee.
Worked example — a 24×18×12 in checked suitcase
Enter 24 inches for length, 18 inches for width and 12 inches for height — a fairly typical large checked suitcase. Total linear inches comes to 24 + 18 + 12 = 54.0 inches, comfortably inside the 62-inch limit most major airlines apply to standard checked bags before charging an oversize fee.
Push those same three dimensions up a bit — a 28×20×14 in case, for example — and the total lands exactly on 62 linear inches, right at the typical threshold; go larger still, to 30×22×15 in, and the total climbs to 67 linear inches, five inches over the line and likely to trigger an oversize charge at check-in.
Questions
What's a typical airline's linear-inch limit for checked baggage?
Most major airlines cap standard checked baggage at 62 linear inches (158 cm) — length plus width plus height combined — a guideline set by the International Air Transport Association and adopted by most global carriers. Some budget airlines, international routes and premium cabins use different numbers, so it's worth checking your specific airline's page before a trip, especially if your bag is close to the limit.
Does linear inches include the bag's wheels and handles?
Yes. Airlines measure the outer shell of the packed bag as it will actually be handled, which means protruding wheels, handles and any external pockets or straps count toward all three dimensions. A hard-shell case that measures exactly to its listed dimensions can still land a few inches over the limit once wheels sticking out at the base are included.
Is linear inches the same as dimensional weight?
No. Linear inches simply adds length, width and height together, which is how most airlines size checked baggage. Dimensional weight, used by parcel carriers like UPS and FedEx, multiplies those same three dimensions and divides by a size factor to produce a weight-equivalent number for pricing shipments. The two measurements answer different questions and aren't interchangeable.
What happens if my bag goes over the linear-inch limit?
Airlines typically charge an oversize-baggage fee, which runs well beyond the standard checked-bag fee and can exceed $100 to $200 depending on the carrier and route. Some airlines also apply a separate, higher limit above which the bag can't be checked at all and must ship as air cargo instead — worth checking before you arrive at the airport with an already-packed bag.
Do carry-on bags use the same linear-inch rule?
Not usually. Carry-on bags are typically restricted by a smaller set of individual length, width and height maximums, often around 22×14×9 inches, that must each be met separately rather than a single combined linear-inch total. This calculator is built around the checked-baggage convention; check your airline's specific carry-on dimensions separately before packing a bag you intend to carry on.