Every guide to carry-on rules obsesses over three numbers — 22 x 14 x 9 inches — and stops there. That’s fine if you only ever fly inside the United States, where the tape measure is the whole rule. The moment you fly Emirates, Qantas, Lufthansa or a European budget carrier, there is a second rule waiting: the scale, and it is far less forgiving than the sizer, because a soft bag can be squashed and a heavy bag cannot be talked down.
This is the reference page for that second rule. Every figure below is read from the carrier’s own baggage page, dated, and cited at the bottom — and where an airline publishes no weight limit at all, we say that rather than repeating a number someone made up.
Cabin baggage weight limits, airline by airline
Published cabin baggage weight limits by airline, with carry-on dimensions| Airline | Published cabin weight limit | Carry-on dimensions |
|---|
| American | None published | 22 x 14 x 9 in (56 x 36 x 23 cm) |
| Delta | None published | 22 x 14 x 9 in (45 linear in) |
| United | None published | 22 x 14 x 9 in |
| Southwest | None published | 24 x 16 x 10 in |
| JetBlue | None — stated as “no weight limit as long as you can lift it” | 22 x 14 x 9 in |
| Alaska | None published | 22 x 14 x 9 in incl. wheels & handles |
| Frontier | 35 lb (15.9 kg) | 24 x 16 x 10 in |
| Ryanair (priority cabin bag) | 10 kg (22 lb) | 55 x 40 x 20 cm |
| easyJet | 15 kg (33 lb), and you must be able to lift it yourself | Small bag 45 x 36 x 20 cm |
| Lufthansa | 8 kg (17.6 lb) | 55 x 40 x 23 cm |
| Emirates (Economy) | 7 kg (15 lb) | 115 cm total (L + W + H) |
| Qantas (international Economy) | 7 kg (15 lb) | One carry-on + one small personal item |
Read across those rows and the pattern is stark. The six largest US carriers on this list publish nocabin weight figure. Cross the Atlantic or the Pacific and 7–10 kg is the norm. A US traveler can fly for twenty years without a bag ever being weighed, then get stopped on their first Emirates flight with a backpack that has never been a problem before. Nothing about the bag changed; the rule did.
What “none published” actually means
It does not mean unlimited. It means the airline chose not to set a number, and left the constraint physical: you have to lift the bag into the overhead bin yourself. JetBlue says this in as many words. In practice a cabin bag that a passenger can’t hoist overhead gets taken off them at the door regardless of what any policy page says.
Two practical consequences. First, on US domestic flights, stop optimizing for weight and optimize for size — the sizer is the only gate, and our measuring guideis the relevant page. Second, don’t generalize from that experience. “My bag has always been fine” is a statement about the airlines you have flown, not about your bag.
Where limits are genuinely enforced
Enforcement is regional and it is predictable enough to plan around.
- Middle East and Asia-Pacific long-haul: weighing at check-in is routine and 7 kg is common. This is where a one-bag traveler with a packed 40L pack is most likely to have a problem.
- European budget carriers:weighing happens, but the bag-size gauge at the gate is the more aggressive enforcement point, since the paid cabin-bag allowance is what they are policing. Ryanair’s priority bag limit is 10 kg; easyJet publishes 15 kg.
- European full-service carriers:a published limit (Lufthansa’s 8 kg) that is enforced inconsistently — usually at check-in desks, rarely at self-service bag drop, occasionally at the gate on a full flight.
- US domestic: effectively never on the carriers above, with Frontier the exception that publishes a figure.
The honest planning rule: if your itinerary contains one weight-capped carrier, pack to that carrier’s limit for the whole trip. You cannot repack a suitcase-worth of belongings in a check-in queue.
Your empty backpack is a fifth of a 7 kg allowance
This is the part almost nobody accounts for, and it is the reason we publish empty weight as a spec on every pack we cover rather than treating it as a footnote. A 7 kg allowance is 15.4 lb. Here is what the bag itself takes out of it, using each maker’s own published figure:
Published empty weight of the packs we cover, as a share of a 7 kg cabin allowance| Pack | Capacity | Empty weight | Share of a 7 kg allowance |
|---|
| Sea to Summit Ultra-Sil Day Pack | 20 L | 0.16 lb (2.5 oz) | 1% |
| Pacsafe Metrosafe X | 20 L | 1.87 lb | 12% |
| Hynes Eagle 40L | 40 L | 2.2 lb | 14% |
| tomtoc Navigator-T66 | 40 L | 2.65 lb | 17% |
| Cotopaxi Allpa 35L | 35 L | 2.94 lb | 19% |
| Osprey Farpoint 40 | 40 L | 3.1 lb | 20% |
| Osprey Fairview 40 | 40 L | 3.2 lb | 21% |
| Nomatic Travel Bag 40L | 40 L | 3.42 lb | 22% |
| Peak Design Travel Backpack 45L | 35 L standard / 45 L expanded | 4.5 lb | 29% |
The spread between the lightest and the heaviest 40L pack here is 1.22 lb — about 0.55 kg, or 8% of a 7 kg allowance. That is roughly a day’s clothes, bought back before you have packed a single item. It is also the single strongest argument for caring about a spec that reads like trivia on a US domestic booking.
The last row is the outlier worth studying, because it shows what the top of the market charges you in grams. At a published 4.5 lb the Peak Design Travel Backpack 45L is the heaviest bag we cover without wheels, and on a 7 kg ticket it spends close to a third of your allowance on the bag. Four weatherproof access points and a shell that holds its shape are the reason; whether that is a fair trade is entirely a question of which airlines you fly.
Note how many packs in our registry have no published weight at all. That gap is concentrated at the budget end, and on a weight-capped carrier it matters: you cannot subtract a figure the maker won’t state. It is why our spec tables print “Not published” instead of an estimate.
The lightest bags we cover
If you fly weight-capped carriers regularly, these are the three worth knowing about. All three publish their weights, which is the first hurdle a bag has to clear to be considered here at all.
#1Lightest 40L carry-on
Hynes Eagle 40L Flight-Approved Carry-On Backpack
The perennial budget one-bag pick. A 40L clamshell with a real hip belt for a fraction of the premium price — genuinely capable for the money. You give up refinement and long-term durability, but for occasional trips it punches far above its cost.
Strengths
- +40L clamshell with a hip belt at a budget price
- +Compression straps to cinch a light load down to size
- +A frequent recommendation in one-bag communities
Trade-offs
- −Materials and zippers aren't built for years of hard use
- −No premium warranty to fall back on
| Capacity | 40 L |
|---|
| Weight (empty) | 2.2 lb |
|---|
| External dimensions | 20.1 x 13.4 x 9.8 in |
|---|
| Carry-on fit (our read) | Carry-on (check strict carriers) |
|---|
| Laptop sleeve | 15.6 in |
|---|
| Material | Water-repellent polyester |
|---|
| Warranty | Not published |
|---|
Fit note. A capable 40L for the price. Treat it as a few-years bag rather than a buy-it-for-life pack, and the value is hard to argue with. Same 40L strict-carrier caveat applies.
Specs read from the product listing, on July 21, 2026. “Not published” means the maker does not state that figure.
#2Lightest structured 40L
tomtoc Navigator-T66 40L Travel Backpack
A lot of well-built 40L for the money. A structured clamshell with a protective laptop compartment and a lifetime warranty that undercuts the premium brands by a wide margin. The trade-off is a simpler harness — fine for airport-to-hotel, less so for long walks under load.
Strengths
- +Structured clamshell and a well-padded laptop compartment
- +Lifetime warranty at a mid-tier price
- +Clean, business-appropriate looks
Trade-offs
- −Simpler hip belt and back panel than an Osprey — less comfortable under a heavy load
- −At 40L, the same strict-carrier caveat applies when packed full
| Capacity | 40 L |
|---|
| Weight (empty) | 2.65 lb |
|---|
| External dimensions | 20.5 x 13 x 9 in |
|---|
| Carry-on fit (our read) | Carry-on (check strict carriers) |
|---|
| Laptop sleeve | 17.3 in |
|---|
| Material | Recycled 1680D PET fabric, YKK zippers |
|---|
| Warranty | 1-year (2-year with registration) |
|---|
Fit note. The tomtoc's strength is protective tech carry at a mid price; its weakness is the suspension. If you'll walk far with it loaded, budget for the comfort gap versus a hip-belted Osprey.
Specs read from the product listing, on July 21, 2026. “Not published” means the maker does not state that figure.
#3Lightest second bag
Sea to Summit Ultra-Sil Ultralight Day Pack 20L
Twenty liters that weigh two and a half ounces and stuff into their own pocket at roughly the size of a lemon. This is the second bag you carry because you can't feel it — a beach, a market, a day hike — and it is emphatically not a bag to carry a laptop or a heavy load in.
Strengths
- +2.5 oz and packs to about 2 x 4 x 7 inches — it disappears in a main bag
- +20L is real capacity, not a token amount
- +Simple, durable siliconized nylon with nothing to break
Trade-offs
- −No padding, no frame, no laptop sleeve — thin straps bite under weight
- −Water-resistant only: unsealed seams and an exposed zipper let water in
| Capacity | 20 L |
|---|
| Weight (empty) | 0.16 lb |
|---|
| External dimensions | Not published |
|---|
| Carry-on fit (our read) | Personal-item sized |
|---|
| Laptop sleeve | Not published |
|---|
| Material | Ultra-Sil siliconized nylon |
|---|
| Warranty | Not published |
|---|
Fit note. Sea to Summit publishes the numbers that matter for a packable: 20L capacity, 2.5 oz (72 g) empty, and a packed size of about 2 x 4 x 7 in. They also state plainly that the fabric is waterproof but the pack is not — the seams aren't sealed and the zipper isn't covered. That honesty is why it's here.
Specs read from the product listing, on August 11, 2026. “Not published” means the maker does not state that figure.
Getting under the limit
In rough order of how much weight each move actually saves:
1. Wear the heavy things. Boots, jacket and the thickest layer go on your body, which no carrier weighs. On a 7 kg allowance this is frequently the entire difference, and it costs nothing.
2. Move density into the personal item. Chargers, cables, a book, toiletries and a spare pair of shoes are small and heavy. Weight limits are almost always applied to the cabin bag alone, so keep the personal item deliberately under-filled on the outbound and use it as the release valve at check-in. Our personal item vs carry-on guide covers how the two allowances differ.
3. Cut the liquids.Water is a kilogram per liter. A full toiletry kit is often 1–1.5 kg of a 7 kg allowance, and solids — shampoo bar, solid deodorant, toothpaste tabs — remove most of it. See the liquids rule guide, which solves for space; on a weight-capped carrier it also solves for the scale.
4. Buy a lighter bag, eventually.Worth 0.5–1 kg, but it is a purchase rather than a packing decision, so treat it as the long-term fix rather than the one you make the night before.
5. Take fewer things.The unglamorous one that beats all of the above. Five days of clothes plus a wash mid-trip covers two weeks — the method is in two weeks in a carry-on.
Two things this page can’t do for you
It can’t cover your fare.Allowances vary by cabin and fare class as well as by carrier — Lufthansa’s Economy Basic, for example, excludes the carry-on entirely and allows only a 40 x 30 x 15 cm personal item. Business and first cabins usually get more. Check the allowance attached to the ticket you actually bought.
It can’t stay current on its own.Airlines change baggage rules with no notice and they trend stricter. The figures above are dated at the bottom of this page, and the airline’s own page is linked for every one of them. Before you fly, click through to the carrier and confirm — that takes thirty seconds and it is the only version of this information that is guaranteed current.