Bag sizer: does it fit your airline?

Free tool — neutral comparison, no airline spin

Sizer boxes differ by airline and the fine print is where gate-check fees live. Measure your bag including wheels, handles and bulging pockets, enter the numbers, and compare the verdict across every airline at once. Rotation is allowed — any orientation that fits the box passes.

How to measure so the verdict holds at the gate

Gate agents do not measure the bag you think you own — they drop it into a metal sizing frame. Three habits that keep the verdict honest: measure the bag packed, because a stuffed front pocket adds real depth; include everything rigid, since wheels and handles count on most airlines (Alaska says so explicitly); and use the frame-friendly orientation — sizer boxes accept the bag in any rotation, so sort your three sides longest-to-shortest exactly as this tool does.

The second trap is not size at all: it is the fare. Ultra-low-cost carriers and basic fares on United, Air Canada, WestJet and Porter can strip your ticket down to a personal item — a bag that fits the frame perfectly still earns a gate fee on those tickets. That is what the fare selector above models, using each airline's published policy. Weight is the third dimension: Frontier and Sun Country cap cabin bags at 35 lb, Flair at 22 lb, Aeromexico at 22 lb combined, and Air Canada simply requires you to lift the bag yourself. If your bag fails on inches, check the full airline reference — if it fails on fare, upgrade before the gate makes the decision for you.

Limits are the airlines' published carry-on maximums (wheels and handles included where stated), re-verified 2026-07-30 — see each airline's page for its source. Weight limits vary; basic/ultra-low fares can exclude the overhead bag entirely. When the airline is stricter, the airline wins.