Duffel Bag Sizes Explained

The size ladder, in published figures

Notice how loosely the two columns track each other. The Patagonia Black Hole 40 publishes 40 L of capacity inside a box of 50.0 L — it spends a fifth of its exterior on shape and fabric. The Osprey Daylite Duffel publishes 45 L inside a 43.4 L box, which is more capacity than its own outside dimensions enclose, because a soft bag stretches and capacity is measured packed.

Neither maker is being dishonest. They are measuring different things. Only one of the two — the exterior — is what a gate sizer checks.

30 to 45 liters: the carry-on band

A duffel in this band is competing with a carry-on case, and the deciding figure is depth. The standard box eight of our eleven US carriers publish is 22 × 14 × 9 in.

• Eagle Creek Cargo Hauler 40 — 9 in deep as published, inside the box on all three sides, clears 11 of 11 US carriers.
• Osprey Daylite Duffel 45 — also 9 in, also 11 of 11, and five liters bigger for $54 less.
• Patagonia Black Hole 40 — 10.6 in deep, which is 1.6 in over the standard limit. It clears 1 of 11.

Three bags, two of them nominally the same size, and a fit result that ranges from every carrier to almost none. The carry-on duffels ranked goes through that shelf properly.

60 to 110 liters: the checked band

Above roughly 50 L a duffel stops pretending to be a carry-on, and the governing figure changes from a three-dimension box to a single number: linear inches, the three dimensions added together. Almost every US carrier publishes 62 in as the checked limit.

Both wheeled duffels in our ledger clear it. The Eagle Creek at 30 × 14 × 15 in totals 59 in, and the Patagonia at 27 × 13 × 14.5 in totals 54.5 in. That is worth knowing, because the two large hardside cases we track publish figures over the same limit. How linear inches are measured is the reference for that rule.

What size to actually buy

• Weekend, carried on → 40 to 45 L, with published depth of 9 in or less. That is a bag you never check.
• One checked bag for two weeks → 70 to 90 L. Above that you will hit the 50 lb weight cap before you fill the bag.
• Gear hauling, expedition, team kit → 100 L and up, and check the linear inches before you buy: 110 L can be under the limit, as the Eagle Creek is, or over it, depending entirely on the shape.
• Anything you will carry far → check the empty weight. The spread in this ledger is 1.4 to 9.04 lb.

One thing to distrust

Round capacity numbers. A duffel advertised at exactly 40 L or 70 L is quoting a design target; the published dimensions are the measured object. When the two disagree — as they do on three of the five bags here — the dimensions are what the airline uses and the capacity is what the marketing uses.

Where a maker publishes no capacity at all, this site prints “Not published” rather than deriving one from the box, because a box volume and a stuffed capacity are not the same measurement and pretending otherwise would put a made-up number in a comparison table.