Quick Answer: What Are Linear Inches?
Linear inches are the total of a package or luggage’s three outside dimensions: length + width + height. If your dimensions are already in inches, you simply add them. If they are in centimeters, convert to inches first, then add. This measurement is widely used by airlines, shipping companies, storage providers, and movers to determine if an item meets size limits.
How Do You Calculate Linear Inches Step by Step?
- Measure the longest side (length).
- Measure the second side (width).
- Measure the third side (height/depth).
- Use the same unit for all dimensions.
- Add all three numbers together.
If your dimensions are in centimeters, convert first:
Then apply the linear inches formula using the converted values.
Linear Inches Examples
Example 1: Suitcase in Inches
A suitcase measures 30 in × 20 in × 12 in.
If an airline allows up to 62 linear inches for checked baggage, this bag is right at the limit.
Example 2: Box in Centimeters
A box measures 70 cm × 40 cm × 30 cm.
Convert each to inches:
- 70 ÷ 2.54 = 27.56 in
- 40 ÷ 2.54 = 15.75 in
- 30 ÷ 2.54 = 11.81 in
Add the converted dimensions:
Why Linear Inches Matter for Airlines
Many airlines use linear inches to set baggage size limits for checked luggage. A common limit is 62 linear inches, though rules vary by airline, route, fare class, and loyalty status. If your bag exceeds the limit, you may be charged oversize baggage fees or denied acceptance depending on policy.
Important: Wheels, handles, side pockets, and protruding parts are usually included in measurements. Always measure the true outer dimensions, not just the fabric body of the bag.
| Use Case | Typical Rule | What to Check |
|---|---|---|
| Checked airline bag | Often 62 linear inches max | Include wheels/handles; verify carrier policy |
| Shipping package | Carrier-specific dimensional limits | Linear inches and dimensional weight rules |
| Moving/storage items | Space-planning and fit checks | Doorway/vehicle dimensions and total size |
Difference Between Linear Inches and Square Inches
This is one of the most common points of confusion. Linear inches are a one-dimensional sum of three side lengths. Square inches are area, calculated as length × width. They are not interchangeable.
- Linear inches: L + W + H (used for size limits)
- Square inches: L × W (used for surface area)
- Cubic inches: L × W × H (used for volume)
Common Mistakes When Calculating Linear Inches
- Mixing units: Adding centimeters and inches together without conversion.
- Forgetting protrusions: Excluding wheels, handles, or external pockets.
- Rounding too early: Convert and add accurately before rounding final results.
- Using inside dimensions: Use outside dimensions for airline and shipping compliance.
- Assuming every airline is the same: Limits and fees vary.
How to Measure Luggage Correctly
Place your luggage on a flat surface and use a rigid tape measure. Measure:
- Length: Longest side from end to end.
- Width: Side-to-side distance at the widest point.
- Height/Depth: Front-to-back thickness at the deepest point.
If your bag expands with a zipper extension, measure it in the expanded state if you plan to travel that way.
Linear Inches for Shipping and E-Commerce
For online sellers and shippers, linear inches help with carton selection and carrier compliance. While dimensional weight often drives shipping cost, linear size still matters for acceptance thresholds and surcharge triggers. Oversize packages may incur additional handling or oversized package fees.
Best practice is to keep a packing chart with common box sizes and their linear-inch totals. This speeds up fulfillment and prevents last-minute label corrections.
Practical Tips to Stay Under 62 Linear Inches
- Choose rounded-corner luggage designs with compact wheel systems.
- Avoid overstuffing expandable sections unless needed.
- Use compression cubes to reduce bulging.
- Measure before you leave for the airport, not at check-in.
- If near the limit, re-check with a second tape measure for accuracy.
Formula Recap
Use this simple method every time:
If dimensions are metric:
Frequently Asked Questions
Is 62 linear inches the same for every airline?
No. Many airlines use 62 linear inches for standard checked bags, but rules can differ by route, ticket type, and fare brand. Always confirm with your airline directly.
Do wheels and handles count in linear inches?
Yes, in most airline and shipping contexts. Measure the maximum outside dimensions including fixed protrusions.
Can I calculate linear inches with centimeters?
Yes. Convert each dimension from centimeters to inches by dividing by 2.54, then add the three values.
What if only one dimension exceeds the limit?
Linear inches are based on the total sum. A large single dimension can still cause the total to exceed the limit and trigger oversize rules.
Are linear inches used for carry-ons?
Carry-ons are usually restricted by individual dimensions rather than linear inches, though some carriers reference both. Check your carrier's carry-on chart.
Final Takeaway
If you’ve ever asked, “How do you calculate linear inches?” the process is straightforward: measure length, width, and height, then add them together in inches. This simple calculation can save you from airline oversize fees, shipping surprises, and packaging errors. Use the calculator on this page whenever you need a fast, accurate result.