What this calculator does
Linear inches is the sum of a bag length, width and height. It is not a volume or a diagonal, just the three dimensions added together, and almost every airline uses it for checked baggage. The common limit is 62 linear inches, which is 158 cm.
Because the three add rather than multiply, bags of very different shapes can measure identically. A tall narrow case and a short wide one can both come to 62, which is why a bag that looks oversized may pass and a modest-looking one may not. Wheels and handles count, and they are what usually pushes a bag over.
The formula
The three dimensions are added to give the linear measurement, which is compared against the limit entered. The centimetre equivalent uses 2.54 cm to the inch. The volume figure is included for comparison only, to show how differently shaped bags of the same linear size can hold quite different amounts.
| Term | Meaning |
|---|---|
| Linear inches | Length plus width plus height, added rather than multiplied. |
| Checked limit | Commonly 62 linear inches, or 158 cm, though it varies by airline and fare. |
| Carry-on limit | Commonly 45 linear inches, around 115 cm, and usually enforced by a sizer at the gate. |
| Overall dimensions | Measured including wheels, handles and any external pockets, not just the main compartment. |
The inputs explained
| Field | What to enter |
|---|---|
| Length (in) | The longest dimension, in inches, measured including wheels and handles. |
| Width (in) | The width, in inches. |
| Height (in) | The depth or thickness, in inches, measured when the bag is packed rather than empty. |
| Airline limit (in) | The airline limit to check against. 62 inches is the most common for checked bags, and 45 for carry-on. |
When to use it
Checking a bag before a flight
The purpose the measurement exists for. Oversize fees are charged per bag per sector and are usually far more than the value of whatever pushed it over.
Choosing a suitcase
Listed dimensions are often for the case body alone, with wheels and handle extra. Adding the real external measurements is the only way to know whether a bag marketed as compliant actually is once packed.
Comparing two bags of the same rated size
The volume figure shows how much two bags at the same linear measurement differ in what they hold. A deeper, squarer bag holds more than a long flat one at the same 62 inches.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
At what depth does a 28 by 20 inch bag go over the limit?
The length and width held fixed while the depth increases, which is what happens as a bag is overpacked.
| Depth | Linear inches | Against the limit | Volume |
|---|---|---|---|
| 8 in | 56.0 in | Within limit (6.0 in to spare) | 4,480 in³ |
| 12 in | 60.0 in | Within limit (2.0 in to spare) | 6,720 in³ |
| 14 in | 62.0 in | Within limit (0.0 in to spare) | 7,840 in³ |
| 16 in | 64.0 in | Over by 2.0 in | 8,960 in³ |
| 20 in | 68.0 in | Over by 6.0 in | 11,200 in³ |
Questions
Do wheels and handles count?
Yes. Airlines measure the greatest external dimensions, and a sizer at the gate is a physical box the bag either fits in or does not. Wheels and a recessed handle typically add two to three inches to the length, which is enough to take a bag marketed as 62 inches over it.
What is the usual carry-on limit?
Around 45 linear inches, roughly 115 cm, though carry-on is more often specified as three separate maximum dimensions rather than a total, because the constraint is fitting the overhead locker. Check the individual dimensions as well as the sum.
What happens if a bag is over?
An oversize fee, charged per bag and usually per sector, so a return trip is charged twice. Above a second and much higher threshold, often 80 linear inches, many airlines will not carry the bag as ordinary baggage at all.
Is 62 linear inches the same as 158 cm?
Yes, near enough. 62 inches is 157.48 cm, and airlines quoting the metric figure round it to 158. A bag right on the line by one measure is on the line by the other, so there is no advantage in choosing which unit to be measured in.
For the volumetric weight couriers charge on, which is a different calculation entirely, see the dimensional weight calculator. For sizing boxes for a house move, see the moving boxes calculator.