What Actually Fits in Each Kind of Bag

Every bag is sold by its name. Sling, messenger, backpack, duffel. None of those words tell you the one thing you need, which is what the bag actually holds.

Capacity is the honest way to compare carry, and it is measurable. Here is what each kind holds, using dimensions we publish rather than adjectives anyone can write.

Slings Hold What Your Pockets Cannot

A sling runs around 12 by 6 by 3 inches. In practice that is a phone, a wallet, keys, a charger and cable, sunglasses, a passport, and a paperback if you are careful.

What it does not hold is a laptop or a tablet in a case. That is not a shortcoming. A sling is sized to keep your pockets empty and your hands free, and one large enough for a laptop has stopped being a sling.

Look at our slings if the largest thing you carry daily is a phone.

Messengers Are Built Around One Flat Object

Ours run 16 to 17 inches wide and about 5 inches deep. That depth is the number people skip, and it is the one that decides what fits.

Five inches is a laptop, a notebook, a charger, and a folded jacket at a push. It is not a gym kit and it is not a change of clothes. A messenger is deliberately shallow, because a deep flat bag sags and swings against your hip when you walk.

Two of our messengers are sold in a 15.6 and a 17.3 version, which is the only reliable way to buy for a specific laptop.

Backpacks Are the Only Format That Scales

Ours run from 17 by 12 by 4 inches at the small end to 19 by 12 by 7 inches at the large end.

That range matters more than it looks. The difference between the two ends is mostly depth, and depth is what turns a laptop bag into a bag that also takes lunch, a jumper, a water bottle and a pair of trainers.

A 4 inch deep backpack is a slim commuter. A 7 inch deep backpack is a day bag you can also fly with. Both are backpacks and they are not remotely the same purchase. The backpacks are here.

Duffels Are Measured in Nights, Not Litres

Ours run 20 to 22 inches long, and the full-grain leather one is sold in four sizes from 21 up to 32 inches.

The useful translation is nights:

• 20 to 22 inches is one or two nights
• 24 inches is a long weekend, or two nights plus a suit
• 30 to 32 inches is a week, or a week plus boots

Most people buy one size up from what they need. A duffel that is not full sags in the middle and everything inside it moves around, so a slightly small bag packed properly carries better than a large one half empty. The duffels are here.

The Number Nobody Publishes

External dimensions are the outside of the bag. The compartment is smaller, and how much smaller depends on the padding and the structure.

This is why a 16 inch messenger is a sensible home for a 14 inch laptop and a risky one for a 16 inch laptop, even though the numbers look like they match. Roughly an inch disappears into the walls.

We publish the external dimensions on every product page, and where a bag is built for a specific laptop size we state that size instead of leaving you to do the arithmetic. Anyone who gives you neither is asking you to guess.

Common Questions

Can a Sling Take a Tablet?

A bare tablet, usually. A tablet in a keyboard case, usually not. Check the published width against the case rather than the tablet.

Is a Bigger Duffel Always Safer?

No, and this is the most common sizing mistake. An underfilled duffel loses its shape and becomes harder to carry than a smaller one packed full.

Which Format Works for Both Work and Weekends?

A backpack at the deep end of the range, around 18 to 19 inches tall and 7 inches deep. It is the only single bag that genuinely covers a commute and an overnight.

Sling or Messenger for the Office?

That depends on context rather than capacity, and we wrote about it separately in our guide to carrying a sling or a messenger to work.