Michael Turner
Answer: Bring a compact rucksack that fits within 18 x 14 x 8 in (45 x 35 x 20 cm) and stow it under the seat – that meets the carrier’s under‑seat allowance for standard economy bookings and keeps you off the gate‑check list in most cases.
Dimensions to follow: Typical under‑seat allowance ~18 x 14 x 8 in (45 x 35 x 20 cm); standard overhead cabin allowance ~22 x 14 x 9 in (56 x 36 x 23 cm). If the packed rucksack exceeds under‑seat volume or has a rigid frame, consider it equivalent to the overhead piece and expect possible gate intervention.
Packing recommendations: Place heavy items at the base, use a slim laptop sleeve, remove or collapse protruding external pockets, and zip the pack before measuring. Measure while packed; soft packs often compress and will qualify, rigid packs usually will not.
Fare and route exceptions: Many economy fare classes allow both an under‑seat piece and an overhead carry, but select discounted fares or certain international itineraries restrict overhead privileges. Review your booking rules and the carrier’s official allowance (search by IATA code DL) before travel to avoid surprises.
At the airport: During boarding, position the rucksack beneath the seat in front of you. If a gate agent asks for a gate check, remove valuables and accept the tag; oversized pieces may be checked at the gate and returned at the aircraft door or baggage claim depending on the flight.
Using a small rucksack as your underseat carry for this airline
A compact rucksack that fits beneath the seat is accepted as your underseat bag on most flights with the carrier; aim for no more than 18 x 14 x 8 in (45 x 35 x 20 cm) when packed.
Dimensions & practical verification
Official overhead allowance is 22 x 14 x 9 in (56 x 35 x 23 cm); anything smaller and stowable under the seat will be treated as the underseat piece. Measure the bag when fully packed (including any protruding straps, external pockets and laptop sleeve). Soft-sided packs compress better than framed models; rigid or wheeled packs are more likely to be flagged as carry-on rather than underseat.
Fare rules and gate handling
Main Cabin and higher fares permit one overhead bag plus one underseat bag. Basic Economy fares permit only the underseat piece – no overhead carry-on. At boarding agents’ discretion, oversized underseat bags may be gate‑checked; to avoid unexpected checks or fees, consolidate valuables and electronics in a clearly underseat‑sized pack and be prepared to demonstrate fit at the gate or check‑in counter.
Quick checklist: measure packed external dimensions, remove rigid add‑ons or wheels if possible, place laptop in a separate sleeve only if it still allows the bag to sit flat under the seat, and use a compressible tote for short trips when you expect strict enforcement.
Carry-on size limits and where to find the official dimensions
Use a small under‑seat carry that does not exceed 18 x 14 x 8 inches (45 x 35 x 20 cm); standard overhead allowance is 22 x 14 x 9 inches (56 x 35 x 23 cm) including wheels and handles.
Official source locations
Official measurements are posted on the airline’s baggage pages (example: https://www.delta.com/us/en/baggage/overview). Check the sections titled “Carry‑on baggage” and “Underseat bag” on that page. Additional authoritative places: the booking confirmation’s baggage section, the mobile app under “My Trips” or “Baggage”, and the carrier’s FAQ for international and Basic Economy rules.
How to verify and measure
Measure external length x width x height and include wheels, handles and exterior pockets. For mixed itineraries, open the carrier’s baggage page for each operating airline. Use the carrier’s published dimensions rather than suitcase manufacturer labels. If unsure, bring the bag to the gate sizer or contact Reservations with your reservation code for a definitive answer.
How to measure your daypack (width × height × depth) to meet the airline’s size limits
Measure with a rigid tape: include all external parts. Target the carrier’s maximum of 18 × 14 × 8 in (45.7 × 35.6 × 20.3 cm) and record width, height and depth as the outermost points, including straps, pockets, wheels and handles.
Place the bag on a flat surface in the orientation you intend to stow it (usually upright or laying flat under the seat). For soft constructions, pack it as you would for travel and compress firmly before measuring; for hard shells, measure the outer casing without deforming it.
Definitions: width = side-to-side at the widest external point (include side pockets and zipper pulls); height = top-to-bottom including any top handles or protruding roll-tops; depth = front-to-back including wheels, feet or front pockets. Always measure to the furthest protrusion.
Include detachable parts in both configurations if possible: measure once with straps/handles tucked and once with them extended, then use the larger result. If a rigid wheel or handle assembly extends beyond the case, count that extension.
Measurement tips: press the tape against the bag edges, use a straightedge across bulges for an accurate width, mark extreme points with small tape before reading. Record results to the nearest 0.5 in (or 1 cm), then convert to the alternate system and keep a 0.5 in / 1 cm safety margin below the carrier limit to avoid surprises at the gate.
Features that make a rucksack acceptable as an under-seat carry for major carriers
Choose a slim rucksack with external flat pockets, tuck-away straps, and compressible fabric that measures no more than 18 × 14 × 8 in (45 × 35 × 20 cm) when fully packed.
Look for soft-sided construction (nylon or ballistic polyester) so the bag can be squashed under the seat; rigid frames and top-loading hardshells reduce clearances by 1–2 inches in depth. A dedicated laptop sleeve placed against the rear panel keeps electronics low and thin – aim for a sleeve that fits up to a 13–14″ laptop to avoid added bulk.
Tuck-away shoulder straps and a strap-management system prevent loops from snagging during stowage; zippers and buckles should lie flat. Avoid external wheels or hard telescoping handles: those add 1.5–3 in to depth and often push a carry into gate-checked territory.
Use compression pockets or side cinch straps to reduce measured depth. If the pack has an expansion zipper, keep it closed while boarding; expanded depth commonly exceeds allowed under-seat clearance by 1–2 inches.
For wet-weather gear, prefer a compact umbrella that stows flat or externally in a sleeve – e.g., a compact, heavy-duty model like the best rainproof golf umbrella fits most side sleeves without increasing overall depth.
| Feature | How it helps | Recommendation (measurable) |
|---|---|---|
| Soft-sided shell | Compresses to fit under seat; reduces firm-thickness penalties | Choose materials compressing ≥0.5 in under pressure; avoid hard inserts |
| Low-profile laptop sleeve | Keeps electronics close to rear panel, prevents middle bulge | Sleeve thickness ≤1 in; fits up to 14″ laptops |
| Tuck-away straps | Eliminates external loops that increase measured width/depth | Strap storage pocket or hideaway compartment included |
| Compression/cinch straps | Reduces depth when load is light or mid-size | Straps that reduce depth by ≥1 in when tightened |
| No wheels/hard handle | Keeps depth minimal and fits under seats built for soft goods | Depth savings: 1.5–3 in vs wheeled designs |
| Flat external pockets | Offer quick access without adding bulk to main body | Pocket depth ≤0.5 in when empty; avoid bulky water bottle holders |
Confirm suitability by placing the loaded rucksack on a flat surface and measuring width × height × depth; the golden rule is to stay at or under 18 × 14 × 8 in (45 × 35 × 20 cm) with expansion closed and straps stowed. If measurements approach limits, remove nonessential items (bulky coat, large umbrella) or transfer them to a jacket to ensure compliant under‑seat stowage.
Packing strategies to keep a daypack within an airline small-bag allowance
Pack clothing into a single 12–16 L compression cube and electronics into a separate 4–6 L flat sleeve so the pack remains slim and under most carriers’ small-bag limits.
- Layer for wear: Wear the bulkiest coat/shoes on the plane to free interior space and reduce packed thickness.
- Use compression cubes, not loose folding: Roll T-shirts and underwear, then compress into one cube – saves ~25–35% volume versus flat packing.
- Flat electronics profile: Place tablet/laptop in a thin neoprene sleeve and slide it against the rear panel to maintain a narrow depth.
- Replace liquids with solids: Swap shampoo/conditioner for 30–50 g solid bars; keep rule-of-thumb 100 ml containers to a minimum and store them in one clear 1 L plastic pouch for security checks.
- Shoe-as-container: Pack one pair of compact shoes; fill cavities with socks, spare charger, and small accessories to use dead space efficiently.
- Trim packaging and duplicates: Remove retail boxes, extra cables, and spare manuals; carry a single multiport charger instead of several adapters.
- Minimize external protrusions: Stow removable straps, hip-belts and water-bottle holsters inside the main compartment or zip them into an exterior pocket to avoid added bulk.
- Choose compressible fabrics: Pick merino, nylon, or polyester garments that spring back but compress thinly; avoid heavy cottons and rigid items.
- Use multi-function pieces: Scarf that doubles as a blanket, jacket with lots of pockets, and toiletries that serve multiple purposes shrink the packing list.
- Distribute weight smartly: Heavier objects next to the rear panel keep the pack compact; light, soft items toward the face to prevent bulging.
Quick pre-flight verification: fully zip the loaded daypack, compress it by hand, then place it into an airline sizer or measure width × height × depth; if any dimension exceeds the carrier limit, remove one small cube or swap a bulky garment for a lighter alternative.
Bring a laptop rucksack alongside a carry-on?
Yes – you can usually carry a laptop rucksack in addition to one overhead carry bag if the small bag fits under the seat or meets the airline’s under‑seat allowance; follow the practical steps below to avoid gate‑check or surprises at the gate.
- Target dimensions for under‑seat placement: no more than 18 × 14 × 8 inches (45 × 35 × 20 cm) external when packed; standard overhead limit is typically 22 × 14 × 9 inches (56 × 36 × 23 cm).
- Keep the rucksack’s loaded weight around 7–10 kg (15–22 lb); heavier loads increase the chance staff will ask you to gate‑check it, especially on regional jets.
- Use a slim, lay‑flat laptop compartment or a removable sleeve so the computer can quickly clear security without dumping the whole bag.
- Prefer soft‑sided designs with compression straps or external cinch pockets – they compress to fit under seats better than rigid shells.
- Place liquids, chargers and valuables in the larger carry bag or on your person if a gate‑check is required; never put passports, medication or irreplaceables in checked luggage.
- Wear the rucksack through boarding if bins look full–this reduces the chance it will be measured or asked to be checked.
- For connections on small aircraft, consolidate contents into the overhead carry if necessary; regional turboprops often have no under‑seat allowance.
- Model selection tip: choose a business‑oriented daypack with a TSA‑friendly laptop sleeve, quick‑access front pocket and a built‑in trolley pass‑through – see recommended options: best luggage for frequent business travelers.
- Measure the rucksack fully packed (W×H×D) before travel; if it exceeds target under‑seat dimensions, move nonessential items to the overhead bag.
- At check‑in, confirm with the agent that you will carry one overhead bag plus one small under‑seat bag free of charge for your fare class.
- At security, remove the laptop to a tray or leave it in the sleeve only if the sleeve is checkpoint‑friendly; keep liquids accessible.
- Board early or use priority boarding when possible to secure under‑seat space; if bins are full, be prepared to gate‑check and move valuables to your person immediately.
- If gate‑checked, attach luggage tags securely and request a gate‑check receipt so you can retrieve the bag at baggage claim or at the jetway on arrival.
Follow these specific measures to reduce the risk of having to check your laptop rucksack and to protect electronics and documents during the trip.
Gate actions when a gate agent says your carry bag is oversized
Immediate steps at the gate
Comply with the agent’s direction and shrink the profile right away: remove jackets, scarves, bulky liquids and extra shoes into your coat or pockets to create room for under-seat stowage.
Take out electronics and fragile items (laptop, tablet, camera) and place them in a thin sleeve or on your person so the main bag becomes flatter.
Collapse external straps, empty outer compartments, and tuck any protruding elements (tripod legs, water bottle, umbrella) inside to reduce measured depth and width.
Politely ask the agent to place the bag in the gate sizer while you watch; if a measurement is taken, photograph the sizer with the bag in place and the agent’s badge for later reference.
If the agent insists on gate-checking or a fee
Request the specific option: gate-check with a claim tag, check at the desk, or pay the checked-baggage charge. If gate-check is offered, remove valuables and medications; keep the claim tag and photograph it along with the bag before handing it over.
If a fee is demanded, ask for the amount and a printed receipt. If you believe the decision is incorrect, calmly request a supervisor and show photos of your compressed load and the sizer attempt.
Document everything: timestamped photos of the packed bag, the sizer, boarding pass, and any receipts or claim tags. Use this evidence when filing a dispute with customer service if needed.
If the bag is returned with dirt, stains or odors from being gate-checked or placed in cargo, clean fabric surfaces promptly; for upholstery stains see how to clean cat sick off carpet for stain-removal techniques that apply to fabric linings and seat material.
