Linear Inches Calculator

About the Linear Inches Calculator

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 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 calculator 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.

When This Page Helps

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.

How to Use the Inputs

1. Enter the length, width, and height of your item.
2. Select inches or centimeters as the measurement unit.
3. View the total linear inches and linear centimeters.
4. Check compliance with airline and carrier limits.
5. Enter the actual weight for dimensional weight comparison.
6. Review the carrier-specific size and weight limits table.

Example Calculation

Tips & Best Practices

• Include wheels and handles in luggage measurements — airlines measure the outside.
• Soft-sided bags can often be compressed below size limits; hard-sided cannot.
• For shipping, a slightly smaller box might drop you below a surcharge threshold.
• Compare actual weight vs DIM weight before choosing a carrier.
• USPS Priority Mail flat-rate boxes ignore dimensions — great for dense items.
• Pack a tape measure when traveling to verify measurements on the spot.

What Linear Inches Actually Measure

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.

Airline and Shipping Use Cases

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.

Measuring Correctly

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.

Frequently Asked Questions

• What are the standard airline checked bag limits?

  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.

• What's the carry-on size limit?

  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.

• What is dimensional weight?

  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.

• What's the DIM factor for different carriers?

  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.

• Do I measure the outside of the bag or inside?

  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.

• What happens if my bag is oversized?

  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.