Calculate linear inches for luggage and shipping. Add length + width + height to check airline, UPS, FedEx, and USPS size limits.
Linear inches — the sum of a package's or luggage's length + width + height — is the standard size measurement used by airlines, shipping carriers, and travel companies. Most airlines limit checked bags to 62 linear inches and carry-ons to 45 linear inches. Exceeding these limits means oversized fees of $100-200 per bag.
This linear inches calculator instantly computes your total linear measurement and checks it against limits for all major airlines, shipping carriers (UPS, FedEx, USPS), and travel scenarios. Enter your dimensions in inches or centimeters, and the tool tells you whether you're within limits, by how much, and what fees you might face.
Beyond the simple sum, the calculator also computes dimensional (DIM) weight — used by shipping carriers to price large, light packages. DIM weight = (L × W × H) ÷ DIM factor, and carriers charge whichever is greater: actual weight or DIM weight. This often surprises shippers who assume light packages are cheap to ship. A quick check before packing can save you from surprise fees at the counter or on a shipping invoice.
It gives you the size number airlines and carriers actually use before you get to the counter. That makes it easier to catch an oversize bag or box early, when you can still repack or choose another carrier. It also helps you compare actual weight against dimensional weight so you know which limit is likely to cost more.
Linear inches = Length + Width + Height. Linear cm = Length_cm + Width_cm + Height_cm. Dimensional weight (lbs) = (L × W × H) ÷ 139 (UPS/FedEx domestic). Billable weight = max(actual weight, DIM weight). Volume = L × W × H.
Result: 60 linear inches — fits most airline checked bag limits (62")
28 + 20 + 12 = 60 linear inches. Under the standard 62" checked bag limit by 2 inches. Dimensional weight = (28 × 20 × 12) ÷ 139 = 48.3 lbs DIM weight.
Linear inches are just the outside length, width, and height added together. That sounds simple, but it matters because most airline and parcel rules are written around that single total rather than volume alone. Wheels, handles, and rigid corners still count because they affect the true outside dimensions.
For travel, the number helps determine whether a bag fits standard checked or carry-on limits. For shipping, it works alongside dimensional weight, which prices the space a package occupies. A box can be under a carrier's linear-size limit and still be expensive if its dimensional weight is high.
The most common mistake is measuring the contents instead of the exterior container. Another is mixing centimeters and inches mid-calculation. If you are close to a surcharge threshold, measure twice and round conservatively, because the carrier will usually use its own external measurement at drop-off.
Most US airlines allow 62 linear inches (157 cm) and 50 lbs for standard checked bags. International flights may allow 70 linear inches. Budget airlines like Spirit and Frontier may have stricter or smaller included limits.
Most airlines: 22×14×9 inches (45 linear inches). Some regional aircraft have smaller overhead bins. Personal items (under seat): typically 18×14×8 inches.
DIM weight prices the SPACE a package occupies, not just its mass. A large, light box costs more to ship because it uses truck/plane space. Carriers charge the higher of actual weight vs DIM weight.
UPS/FedEx domestic: divide cubic inches by 139. International: divide by 139 also (changed from 166). USPS uses DIM weight for Priority Mail packages over 1 cubic foot.
Always measure the OUTSIDE dimensions including wheels, handles, and any protrusions. Airline bag sizers measure the outside. Same for shipping — measure the actual box, not the contents.
Airlines charge $100-200 for bags 63-80 linear inches, and $200+ for bags over 80 linear inches. Some airlines refuse bags over 115 linear inches entirely. UPS and FedEx add surcharges for oversize packages.