Methodology
How we evaluate fit This page explains the data sources, assumptions, and rules behind the results you see in Carry‑On Checker.
1) Sources
- Primary: Official airline websites (baggage policy pages and Conditions of Carriage).
- Secondary: Airline help centers and FAQ pages where official pages are ambiguous.
- Out of scope: Third‑party blogs and forum anecdotes do not determine limits; we may reference them for context only.
2) Definitions
| Term | Meaning |
|---|---|
| Carry‑on | The larger cabin bag permitted in overhead bins. Airlines typically specify a maximum Length × Width × Height. |
| Personal item | A smaller item that must fit under the seat in front. If an airline posts a size, we use it; otherwise we provide general guidance. |
| External dimensions | We treat your entries as outer dimensions, including wheels and handles, unless an airline clearly states otherwise. |
3) Unit handling
- You can enter dimensions in inches or centimeters; the tool converts internally using
1 in = 2.54 cm. - Displayed conversions are rounded to the nearest tenth (0.1) for readability; internal comparisons use full precision.
4) Fit logic
- Dimension match: For airlines that publish three separate limits (L, W, H), a bag fits when each entered dimension is less than or equal to the corresponding limit.
- Linear dimensions: If an airline specifies a single “linear” maximum (e.g., L + W + H ≤ N), we compare your sum against that value.
- Personal item: If posted, we use the airline’s under‑seat dimensions. If not posted, we provide conservative guidance based on common aircraft.
- Weight (optional): If an airline enforces a carry‑on weight, the checker will flag it when you add weight to your entry.
- Ties go to the airline: Borderline results are treated as may not fit to reflect real‑world variance in sizers and aircraft bins.
5) Data maintenance
- Refresh cadence: We review airlines on a rolling basis and update promptly when notified of published changes.
- Change notes: Material updates (new size/weight) are recorded with a date stamp on relevant pages.
- Corrections: Found an error? Email customerservice@carryonchecker.net and we’ll verify and fix.
6) Known limitations
- Policies may vary by fare type, route, aircraft, or status; always defer to your airline at check‑in or the gate.
- Gate sizers can differ from posted measurements; manufacturing tolerances and soft‑sided compression can affect outcomes.
- Special items (strollers, musical instruments, medical devices) follow separate rules and are not evaluated by this tool.
7) Responsible use
Carry‑On Checker provides guidance based on published rules and standard assumptions. It is not a guarantee of acceptance for any individual flight. When in doubt, choose a smaller bag or contact your airline.