Linear Inches Calculator - Sum Length, Width, Height

A linear inches calculator is a quick travel-planning tool that adds the length, width, and height of a bag, suitcase, or shipping box into one number expressed in inches. Most major airlines use that single number, called linear inches, to decide whether your luggage fits their carry-on or checked-bag limit, so travelers use this calculator before a flight to avoid oversized-bag fees at the counter.

• • Carry-on Sizing Before a Flight: Measure a roller bag, duffel, or backpack to confirm it stays at or below the 45 linear inch carry-on limit most airlines enforce.
• • Checked-Bag Compliance Check: Confirm the longest side plus the other two stays at or below 62 linear inches, the standard checked-bag maximum.
• • Shipping Box Dimension Check: Add the three external sides of a parcel to know its dimensional size in inches before you buy a postage label.
• • Storage and Closet Planning: Use the same total to estimate the run of a long shelf or the space a stored object will need.

Linear inches is widely used because luggage comes in many shapes, and one number based on length + width + height is easier for airline staff to verify than a more complex volume figure. A 22 x 14 x 9 inch carry-on, for example, sums to 45 linear inches, which matches the standard allowance used by most U.S. and international carriers.

When you plan a trip, the same total in centimeters can be useful because some international carriers publish bag limits in centimeters rather than inches. If you are sizing a custom bag, our bag calculator complements this tool by estimating bag volume, fabric needs, and surface area for sewn projects.

The math behind linear inches is a single addition. Each external side is converted to inches, summed, and compared to the airline thresholds that govern your trip. The same sum also becomes the basis for the dimensional weight used by shipping carriers.

• Length (L): The longest external side of the bag or package, measured in inches (or in cm or mm and converted).
• Width (W): The side-to-side external measurement, perpendicular to the length.
• Height (H): The top-to-bottom external measurement, including wheels, handles, and any fixed external pockets.

If you are working in centimeters or millimeters, the same total still works once you convert each input to inches first. The official inch-to-centimeter ratio is 1 in = 2.54 cm, so dividing your centimeter total by 2.54 yields the matching linear inches.

Once you have the linear inches total, the next decision is whether to fly with the bag or check it. For a quick standalone sanity check of a single dimension, our cm to in calculator converts centimeters to inches and back in one step, which is handy for travelers who measure their luggage in metric units.

According to International Air Transport Association (IATA), the recommended maximum size for a standard checked bag is 62 linear inches (158 cm), calculated as length + width + height.

These four ideas come up every time you compare luggage sizes, so learning them helps you interpret any airline's policy without rereading the rules page.

Linear inches is not the same as cubic inches. A 22 x 14 x 9 carry-on is 2,772 cubic inches but only 45 linear inches, which is why airlines chose linear inches as a quick way to standardize oddly shaped bags and soft duffels.

Carriers like UPS, FedEx, and USPS also use length x width x height, but they divide that product by 139 (retail ground) or 166 (priority services) to get a billable weight in pounds. Knowing both numbers helps you avoid a dimensional-weight reclassification on a low-density shipment.

When you want to express the same bag dimensions in larger units, our inches to yard conversion calculator turns the total into yards and feet for storage and shelving plans.

Follow these five steps to add the three sides of any bag or box and check it against the most common airline baggage limits.

1. 1 Set the Input Unit: Choose inches, centimeters, or millimeters in the unit selector so the calculator knows how to read the three measurements.
2. 2 Measure the Length: Measure the longest external side of the bag or box from seam to seam, including the wheels if they are fixed.
3. 3 Measure the Width: Measure the side-to-side dimension perpendicular to the length, again measuring the outside, not the inside.
4. 4 Measure the Height: Measure the top-to-bottom dimension, again on the outside and including wheels and any external pockets.
5. 5 Read the Total and Airline Status: Watch the linear inches and centimeter totals update in real time, and check the carry-on and checked-bag status chips for a quick Pass or Over read.

Suppose you are packing a soft duffel for a weekend trip. You set the input unit to inches and enter 24 in length, 12 in width, and 10 in height. The calculator sums them to 46 linear inches, just one inch over the 45 in carry-on ceiling, so the carry-on status reads Over and the checked-bag status reads Pass. You can either repack into a 22 x 14 x 9 carry-on or plan to check the duffel for the flight.

Using a linear inches calculator before you fly or ship a box saves time, prevents surprise fees, and lets you shop for luggage with the right size already in mind.

• • Avoids Oversized-Bag Fees: A 1 inch overage on a checked bag can trigger a $100 or more fee at the airport, so checking the total at home is much cheaper than paying at the counter.
• • Confirms Carry-On Compliance: Quickly verifies that a new carry-on fits the 45 linear inch ceiling so you can board without a gate check.
• • Speeds Up Packing: Lets you trim the bag dimensions, or switch to a smaller case, before the day of travel rather than repacking at the gate.
• • Improves Shipping Estimates: Pairs with dimensional-weight rules to predict the billable weight of a box before you buy postage.
• • Works in Any Unit: Accepts inches, centimeters, or millimeters so the same tool works for U.S. and international travelers.

Once the bag is sized, our business travel expense calculator can estimate the rest of the trip's costs so the whole trip stays on budget.

Several real-world conditions affect whether a bag actually meets a published limit, so always read the result as a starting point and confirm the exact airline policy before you fly.

• • Linear inches does not capture girth, so a very long and thin fishing rod case can still fail a fit check even when the linear inches total looks safe.
• • Some carriers apply a single-dimension cap, such as 30 inches in length, in addition to the linear inches total. This calculator does not enforce single-dimension caps.

Always check the airline's own website or your booking email for the most current baggage size rule, because limits change with route, aircraft, and frequent flyer status. The largest external footprint of the bag, including fixed wheels and protruding handles, is what the airline counter measures before deciding whether the bag is carry-on, checked, or oversized.

The inch-to-centimeter ratio is exact, so the 62 linear inch checked-bag limit is always 157.48 linear centimeters, and the 45 linear inch carry-on limit is always 114.3 linear centimeters, which makes it easy to compare a bag measured in centimeters against a limit published in inches.

According to U.S. National Institute of Standards and Technology (NIST), one inch is defined as exactly 2.54 centimeters, so the 45 linear inch carry-on limit is always 114.3 linear centimeters.

According to International Air Transport Association (IATA) Passenger Baggage Rules, the recommended maximum size for a standard checked bag is 158 cm (62 in) calculated as length + width + height, and carry-on dimensions of 56 x 45 x 25 cm (22 x 18 x 10 in) are measured including wheels and handles.

For international trips published in metric units, our inch to meter gives you the metric side of the same dimension so the totals can be checked side by side.