Personal item vs carry-on
Know which bag usually goes under the seat and which one normally goes overhead.
Guides
Learn what to measure, which bag type to choose, and what to verify before trusting a cabin baggage result.

Packing checklist
Before you compare
Pack the bag first, then measure it.
Measure the widest length, width, and height.
Include wheels, handles, straps, pockets, and bulges.
Check whether your fare includes the selected bag type.
Open the official source before you fly.
Know which bag usually goes under the seat and which one normally goes overhead.
Include wheels, handles, side pockets, and the shape your bag has when it is full.
A bag can match dimensions but still require priority, a bundle, or a paid cabin bag.
Use CabinFit as a planning tool, then confirm the airline page before travel.
Bag types
Personal items usually fit under the seat. Carry-ons usually go in the overhead bin and can depend more heavily on fare bundles, aircraft, boarding group, or paid add-ons.

Usually under the seat

Usually overhead bin
Measurement guide
CabinFit compares the numbers you enter. It does not assume a soft bag will compress, and it does not ignore wheels, handles, or pockets that stick out.
Orientation check
Airlines and bag brands do not always list dimensions in the same order. CabinFit checks all six possible orientations before showing a result.
Next step
Use the checker for one airline, compare the same bag across all rules, or build a multi-airline trip plan.