Check your airline website for carryon baggage size limitations. The most common is a maximum of 22? x 14? x 9?. If your duffel bag can be smushed into those dimensions or smaller, then unless your airline has an exceptionally strict limit, you should be OK.

In 2026, airlines have become significantly less lenient with carry-on sizes as they transition toward a near-universal industry standard of 22 x 14 x 9 inches (including wheels and handles). With the "High-Fidelity" carry-on crunch reaching record levels, major carriers like United and American have begun utilizing high-fidelity automated gate sizers or "no-force" pass/fail rules. If a bag bulges or fails to slide into the sizer easily, it is a high-fidelity requirement that it be gate-checked, often for a high-value fee of $65 to $100. Some airlines, like American, are even removing manual sizers to increase "High-Fidelity" gate-agent discretion, leading to more frequent flags for oversized items. For 2026 travelers, "close enough" is no longer a high-value strategy; it is a necessity to measure your bag accurately before heading to the airport. Even if your bag fits the dimensions, "High-Fidelity" regional jets or full flights may still force a gate-check due to overhead bin capacity, making it a high-fidelity best practice to keep essentials in a smaller "Personal Item" bag under your seat.