Guide
Carry-on size guide
What the numbers on a bag's spec sheet mean, and how to tell whether your bag will go in the cabin.
Bag dimensions look precise and behave loosely. A bag listed at 21.5 x 13.5 x 8.5 inches can pass one gate and get stopped at another, because airlines publish different limits, use different sizers, and measure a packed bag rather than an empty one. This guide explains the three numbers that matter and how to check yours before you leave home.
The three measurements
- Height — the longest dimension, measured with the bag standing upright. This is usually the number that fails a sizer.
- Width — side to side. Rarely a problem for backpacks, often a problem for duffels carried on their long axis.
- Depth — front to back. This is the one that grows when you pack. A bag listed at 8.5 inches deep can reach 10 or 11 inches with a jacket stuffed in the front pocket.
Some airlines add the three together and publish a single "linear" figure — 45 linear inches is a common one. Adding your three numbers gives you a quick check, but a bag can be under the linear total and still fail on height alone.
How to measure your own bag properly
- Pack the bag the way you'd actually travel with it, including the front pockets.
- Stand it on the floor against a wall. Don't press it flat.
- Measure to the outermost point of each dimension, including handles, buckles, wheels and bulging pockets. Sizers don't make exceptions for a grab handle.
- Write the packed numbers down. Those are your real dimensions, not the spec sheet's.
- Compare against the airline's stated limits for the specific flight, not a number you remember from a previous trip.
Where the Kanso bags sit
| Bag | Listed dimensions | Linear total | Intended cabin role |
|---|---|---|---|
| Day 18 | 17 x 11 x 6 in (43 x 28 x 15 cm) | 34.0 in | Personal item, under the seat |
| Weekender 28 | 19 x 12 x 8 in (48 x 30 x 20 cm) | 39.0 in | Personal item or overhead, depending on packing |
| Carry 38 | 21.5 x 13.5 x 8.5 in (55 x 34 x 22 cm) | 43.5 in | Overhead carry-on |
| Split 42 | 22 x 14 x 9 in (56 x 36 x 23 cm) | 45.0 in | Overhead carry-on at the upper limit; may need checking |
Carry 38 and Split 42 are designed around common carry-on limits; airline rules vary. Split 42 sits at the upper end and may need to be checked on smaller regional aircraft. We can't promise any bag will be accepted on a given flight, and we won't pretend otherwise.
Questions people actually ask
Does a soft bag get more leeway than a hard case?
In practice a soft bag can compress into a sizer where a hard shell can't. That is not a rule you can rely on — it depends on the airport, the gate and how full the flight is. Pack so the bag fits without compression and you never have to find out.
Do backpack straps count?
They count if they stick out. Straps that flatten against the back panel usually add nothing measurable; a loaded harness with a padded hip belt can add an inch of depth. Carry 38 and Split 42 both have a harness cover, which is one reason we drew them that way.
What's a "personal item"?
The smaller of the two allowances on most airlines, meant to go under the seat in front of you. Day 18 is sized for that role. A packed Weekender 28 sometimes qualifies and sometimes doesn't, so treat it as an overhead bag when the flight is full.
Is 45 linear inches a universal rule?
No. It's common in the United States and not consistent worldwide, and several carriers publish weight limits in addition to dimensions. Always check the specific airline.
Pre-flight checklist
- Packed height, width and depth written down
- Airline's stated carry-on and personal-item limits checked for this flight
- Cabin weight limit checked, if the airline publishes one
- Front pockets not overstuffed
- Straps stowed or covered
- A plan for what you'd remove if asked to check the bag
Next
For two- and three-night trips, read the weekend packing guide. For five to seven nights out of one bag, read the one-bag packing guide. If you'd rather just be told, answer three questions.