A carry-on that works for one airline may be too large, too heavy or excluded from the fare on another. Most major U.S. airlines use limits close to 22 × 14 × 9 inches, while international carriers vary more widely and are more likely to impose weight limits. Before packing, confirm the permitted dimensions, weight, number of bags and fare allowance for every flight in your itinerary. What Are the Carry-On Size Limits for Major Airlines? Carry-on size restrictions vary by airline, but a compliant bag must meet the carrier’s exterior dimensions, weight limit and fare allowance. The tables below focus specifically on overhead carry-on luggage, rather than the broader rules for checked luggage and special baggage. Major U.S. Airlines Many large U.S. airlines follow the 22 × 14 × 9-inch standard, but low-cost carriers may allow different dimensions while charging separately for overhead baggage. Airline Maximum Carry-On Size Weight Limit Personal Item Allowance Included on Lowest Fare Key Exception American Airlines 22 × 14 × 9 in No published limit One, up to 18 × 14 × 8 in Yes Some aircraft and airports may apply additional restrictions Delta Air Lines 22 × 14 × 9 in No published limit on most routes One small underseat item Yes Cabin storage may affect whether the bag remains onboard United Airlines 22 × 14 × 9 in No published limit One, up to 17 × 10 × 9 in Usually no Basic Economy rules vary on selected international routes Southwest Airlines 24 × 16 × 10 in No published limit One underseat item Yes A compliant bag may still be gate-checked if bins are full JetBlue 22 × 14 × 9 in No published limit One, up to 17 × 13 × 8 in Yes The passenger must be able to lift the bag without assistance Alaska Airlines 22 × 14 × 9 in No published limit One small underseat item Yes Smaller aircraft may have limited overhead space Hawaiian Airlines 22 × 14 × 9 in 25 lb One small underseat item Yes The weight limit applies even when the dimensions comply Frontier Airlines 24 × 16 × 10 in 35 lb One, up to 18 × 14 × 8 in No Carry-on pricing depends on the fare and purchase time Allegiant Air 22 × 16 × 10 in No published limit One, up to 18 × 14 × 8 in No A fee normally applies to an overhead carry-on The comparison shows why 22 × 14 × 9 inches is a useful starting point, not a universal standard. Southwest and Frontier permit larger dimensions, while United, Frontier and Allegiant require closer attention to what the fare includes. Major International Airlines International airlines are more likely to limit both size and weight. Some also calculate the weight of the carry-on and personal item together. Airline Maximum Carry-On Size Weight Limit Personal Item Allowance Included on Lowest Fare Key Exception British Airways 56 × 45 × 25 cm 23 kg One small bag, route and cabin rules apply Yes The passenger must be able to lift the bag into the bin Air Canada 55 × 40 × 23 cm No fixed limit One, up to 43 × 33 × 16 cm Route-dependent Selected Economy Basic itineraries include only a personal item Lufthansa 55 × 40 × 23 cm 8 kg One, up to 40 × 30 × 15 cm Fare-dependent Short and medium-haul Economy Basic excludes the overhead bag Emirates 55 × 38 × 22 cm 7 kg in Economy No separate item generally stated for Economy Yes Economy departures from Brazil receive a higher weight allowance Air France 55 × 35 × 25 cm 12 kg combined in Economy One, up to 40 × 30 × 15 cm Not always Basic fares on eligible routes may include only the small bag Qatar Airways 50 × 37 × 25 cm 7 kg in Economy Limited small personal items Yes A laptop and its bag must fit within the cabin allowance Singapore Airlines 115 cm total dimensions 7 kg One small additional item Yes The three sides are added together instead of assessed separately A bag that meets a common U.S. limit may still exceed an international airline’s depth, width or weight allowance. International travelers should pay particular attention to combined weight limits and fares that include only a small underseat bag. Why Is Carry-On Size Only Part of the Airline Rule? Matching the published dimensions does not automatically mean a bag can travel in the cabin. Fare type, weight, carry-on and personal item rules, aircraft size and connecting airlines can all affect the final allowance.  The Fare May Not Include an Overhead Carry-On Some basic fares include only one personal item stored under the seat. Bringing an additional bag to the gate may result in a fee or require the bag to be checked. Review the baggage allowance shown during booking instead of assuming that “Economy” always includes an overhead bag. United, Frontier, Allegiant, Air Canada, Lufthansa and Air France all have fares or routes where the lowest option may exclude it. Size and Weight Limits Are Separate A correctly sized bag can still be rejected if it exceeds the weight limit. This matters particularly on airlines such as Hawaiian, Lufthansa, Emirates, Qatar Airways and Singapore Airlines. Weigh the finished bag, including its wheels, frame and everything packed inside. If an airline combines the weight of the carry-on and personal item, moving a laptop between bags will not reduce the total. Personal Item and Total Bag Allowances A backpack, duffel or tote is not automatically a personal item. It must meet the airline’s stated dimensions and fit completely under the seat.  For airlines using an 18 × 14 × 8-inch personal-item limit, the BAGSMART Moss Overnighter measures approximately 17.3 × 13 × 7.9 inches. Its 30L capacity can support a lightly packed two- or three-day trip, while separate laptop and shoe compartments keep electronics and footwear away from clothing. Because soft bags can bulge when full, measure it after packing rather than treating its empty dimensions as guaranteed clearance. Aircraft Type and Route-Specific Rules The published maximum describes what the airline generally accepts, but the aircraft must still have enough storage space. Regional jets and smaller planes may have bins that cannot accommodate a standard rolling suitcase. Travelers using regional aircraft can review the more specific Delta carry-on size rules for an example of how aircraft and cabin space can affect an otherwise compliant bag. When mobility and packing margin matter, the BAGSMART Blast 28L Travel Backpack offers a more compact alternative to a wheeled case. At approximately 16.5 × 12.2 × 8.1 inches and 0.9 kg, it leaves more room within many common size and weight limits. Its full-opening main compartment supports suitcase-style packing, while the backpack design keeps both hands available during transfers, stairways and public transport. It should still be compared with the rules for the actual flight rather than treated as universally approved. Connecting Flights May Follow Different Rules A connection can place one itinerary under several cabin-baggage policies. The airline selling the ticket may not operate every segment, and a codeshare partner may use a smaller aircraft or a different allowance. Compare every operating carrier before departure. Packing to the strictest size and weight limit is usually the safest choice when the itinerary includes several airlines. The allowance displayed on the ticket or booking confirmation should take priority over a general airline comparison. How Should You Measure Carry-On Luggage? Measure the bag as the airline will see it at the airport: fully packed and standing on its wheels. Product names such as “20-inch carry-on” do not provide all the measurements needed to determine compliance. Include Wheels, Handles and Exterior Pockets Measure the complete exterior height, width and depth. Wheels, fixed handles, protective feet and filled exterior pockets all count. A suitcase body may be within the limit while its wheels push the total height over it. Measure the widest and deepest points rather than the flat center panels. Measure the Bag After Packing Soft-sided bags and backpacks can expand beyond their empty dimensions. A tightly packed front pocket or rounded main compartment may prevent the bag from sliding into an airport sizer. Close every zipper, tighten compression straps and place the bag on a flat surface before measuring. Do not rely on being able to force an overfilled bag into the sizer. Check the Expanded Dimensions An expansion zipper changes the bag’s depth even if the height and width remain the same. A suitcase accepted in its standard form may exceed the limit after expansion. Use the expanded setting only when the resulting dimensions still comply. Otherwise, reserve that additional space for ground travel or for a return journey on which the bag will be checked. Compare Dimensions in the Same Order and Unit Airlines do not always present dimensions in the same order. One may list height × width × depth, while another uses length × width × height. Match each side by its physical orientation and convert inches to centimeters when necessary. For an airline such as Singapore Airlines, add length, width and height and compare the result with the total-dimension limit. Weigh the Fully Packed Bag Use a luggage scale after packing all clothing, toiletries and electronics. Check the personal item at the same time if the airline uses a combined cabin weight. Leave a small margin instead of packing exactly to the limit. Small scale differences and last-minute purchases can otherwise turn a compliant bag into an overweight one. What Happens if a Carry-On Exceeds the Airline Limit? The outcome depends on where the problem is found, how far the bag exceeds the rule and whether the fare includes checked baggage. The Bag May Need to Be Checked An oversized or overweight carry-on may be tagged and placed in the aircraft hold. The same can happen to a compliant bag when overhead bins are full, although involuntary gate-checking is often handled differently from a rule violation. Before boarding, move medication, documents, valuables, power banks and spare lithium batteries into the personal item you will keep in the cabin. Oversize or Overweight Fees May Apply If the bag exceeds the allowance, the airline may charge a checked-bag, gate-handling, oversize or overweight fee. Paying at the gate can cost more than adding baggage during booking or online check-in. A carry-on fee also does not override the physical limit. Purchasing an overhead bag gives you an allowance, not permission to bring one that is too large or heavy. You May Be Asked to Repack the Bag If only one pocket or a small amount of weight creates the problem, airline staff may allow you to redistribute items. This works only when the other bag still meets its own allowance. Wear a bulky layer or move a permitted small item if necessary, but never transfer spare batteries or power banks into checked baggage simply to reduce cabin weight. Conclusion The safest carry-on choice is not simply the smallest bag. It is one that fits the strictest flight in the itinerary, stays within any weight limit and is included with the booked fare. Travelers taking several airlines should pack to the least generous allowance, while those on a single direct flight can follow the operating carrier’s exact policy. Measure and weigh the packed bag once, then confirm the allowance shown in the reservation before leaving for the airport. FAQ Can You Bring Both a Backpack and a Carry-On Suitcase? Usually, yes, if the fare includes one overhead carry-on and one personal item. The suitcase must meet the carry-on limit, and the backpack must fit completely under the seat. Some basic fares include only the backpack-sized personal item. Can a Soft-Sided Bag Be Compressed to Fit the Airline Sizer? Yes, if it fits inside the sizer without excessive force and remains within the stated limit. Overfilled pockets, rigid contents or strained zippers may prevent a soft bag from qualifying even when its empty dimensions are smaller. Do Airlines Check Carry-On Size at Check-In or at the Gate? They may check it at either point. Low-cost carriers and airlines using automated or manual sizers may inspect bags before security, at check-in or during boarding. Enforcement can also increase on full flights. Where Will You Collect Your Carry-On if It Is Gate-Checked? It depends on the airline, airport and aircraft. Some bags are returned beside the aircraft or on the jet bridge, while others go to the regular baggage carousel. Confirm the collection point with the gate agent and keep the baggage receipt.