It all depends on what you use it for, what you want to bring, where are you going, and how long you are going there.

The industry standard for determining backpack and duffel bag size is a measurement of volume, either in cubic liters or cubic inches. For most of us this these measurements do not mean much without some sort of context.

For reference, a one-gallon jug is almost 4 liters. A rolled t-shirt takes up roughly a liter of space.

Consider what the primary use of the bag is, is it a gym bag, a diaper bag, or a catch all for weekend camping trips? Also consider what your packing style is. Are you a boy scout who is prepared for anything? Or are you an Ultralight hotdogger who counts every ounce?

Daypacks usually land anywhere between 20-40 liters. A light packer can get multiple days out of a 30L pack.

Multiday Packs typically fall in the 40–60-liter range. A light packer traveling solo would be able to get a weeks’ worth of stuff in a 50L bag no problem.

Expedition Bags are great for a “catch all” when floating the Smith River (4-day trip), or a weekend long camping trip with family. An expedition bag is usually upwards of 90L. At this point keep in mind, a fully packed 90L duffel will be easily 40-50lbs. So don’t plan on moving it far from your vehicle or vessel without a lot of effort.

Packing Style?

Everybody packs different. So, take all of this with a grain of salt.

Boy scout-is prepared for everything and anything. This person is great to have on a trip, because if you forgot something, they likely brought an extra.

Rationalist-packs sensibly, a pair of underwear for each day, and only what is logical.

Ultralight Hotdogger-leaves everything but the bare essentials. Deodorant, and personal hygiene are secondary concerns.

Carry On Size? 

Carry-on size falls under the 50-liter mark (22 x 14 x 9 inches). So, if your duffel is larger than 50L don’t stuff it full if you want to get it in the overhead compartment. Duffels are versatile in this regard, making them easier to pack in tight spaces.

Your Destination?

Consider where you are traveling and what time of year it is. Is it full blow winter? If so, you might need a more space for layers, a winter coat, especially if you don’t want to sweat your way through the airport. And vice versus, if you are traveling to a tropical climate for a surf trip, you might need a pair of boardshorts and a few t-shirts. In that case you might get away with a much smaller bag.

Our Duffel Bags

The Smith and Rogue design team whittled our Ramble On Duffel Bag Collection down to three sizes, small (30L), medium (55L), and large (95L). This we think corresponds to the day, multi-day, expedition categories mentioned above.

In addition to our duffels, we expanded the Ramble On Collection to include a 28L + 35L backpacks. The 28L is designed for quick overnight turn arounds. The 35L is enough to get you through a multi-day trip.

For us the 30L makes a great gym bag or weekend bag, the 55L for week long trips, and the 95L for the expedition (fishing trip, rafting/floating, hunting camp, surf-trip, ski bag).   

The Take-Away

The moral of this story, each person has different needs depending on where you are going, what you are bringing, and how long you are going. Figure those things out and you should have a good idea.

Also check out out the video below for more on our Ramble On Duffle Bag and designer Rob G's breakdown of the sizes.