1. Source records
Airline rules are entered from airline baggage pages or other clearly identified policy sources. Bag records favor manufacturer product pages; retailer records are used when manufacturer data is incomplete or unavailable. Each reviewed row keeps a source URL, review date, confidence level, and notes for caveats such as fare class, route, or regional aircraft.
2. Dimension normalization
Bag and airline dimensions are normalized into inches so they can be compared on the same axes. The visualizer treats height, width, and depth as a measured box, then labels dimensions that are missing, estimated, or source-dependent instead of filling gaps with false precision.
3. Fit and practical risk
Fit results compare the bag's published dimensions with the selected airline rule. Rigid bags are treated strictly. Soft bags may receive limited practical-risk context when they are only slightly over a rule, but the site still marks the overage and keeps the result separate from a clean fit.
4. Visual scale checks
The fit visualizer renders the bag against the airline allowance box so the tight axis is visible. When approved product imagery is available, it is shown to scale. When it is not, the page falls back to a dimension-driven silhouette and discloses that limitation.
5. Recommendation ranking
Finder results lead with fit status and spare room, then an active second-airline constraint, source and product evidence, and the selected traveler preferences. Exact-rule guide pages use calculated fit; incomplete or estimated rules use a separately labeled research shortlist. Commerce links do not change whether a bag fits an airline rule.
6. Limits to keep in mind
Recommendations are not guarantees. Airline staff, packed shape, handles, wheels, straps, fare class, aircraft, airport enforcement, and policy changes can change the outcome. If an airline does not publish exact dimensions for a rule, the site labels the result as unknown or estimated and keeps the relevant caveat visible.