The 45L is better for: 1-bag-travel for trips 4 days and longer. More access and organization options. Trips where you need multiple jackets, pairs of shoes, or other bulky clothing.
People Also Ask
For a multi-day, or weekend hike, a 45L to 55L backpack offers enough volume for the average backpacker. The extra capacity allows for carrying more food, water, fuel, and some comfort items you might leave behind for a single night trip.
Whether you're an ultralight thru hiker, lightweight weekend warrior, or even an ambitious day hiker, a 45 liter pack can be the perfect size. If you're just getting started backpacking, a larger pack (55 – 65 liters) will give you more wiggle room and more options.
What size backpack do I need for 2 or 3-days (weekend hike)? For a multi-day, or weekend hike, a 45L to 55L backpack offers enough volume for the average backpacker. The extra capacity allows for carrying more food, water, fuel, and some comfort items you might leave behind for a single night trip.
40-50 Liters (The Ultralight Thru-Hiker)A pack this size can be used for multi-day backpacking trips and even Continental Trail thru-hikes provided you keep a lightweight and minimalist philosophy.
2-3 Day Packs: 35-50 litersA weekend backpack like a standard 40L backpack is big enough to carry a backpacking sleeping bag, small tent, and pad, as well as extra clothing and layers.
21–35 liters: This is the sweet spot for most hiking and travel daypacks. There's enough capacity to hold food, clothing and some extras, like a camera and a book. 36–50 liters: These larger packs are ideal for trips that require additional clothing and gear, such as climbing, mountaineering or non-summer hiking.
A 30L – 50L backpack will be just the ticket. It will be able to hold all your sleeping, cooking, and camping gear you need for trips up to 5 or 6 days.
Large Backpacks: 40+ LitersLarge backpacks have a capacity of 40 liters or more, which is plenty of space for all your travel gear, even on longer journeys. If you're planning a backpacking trip for seven to ten days (or longer if you're travel-savvy and can pack light), this is the size you'll want.
For vacations of 2 to 3 weeks, medium-sized luggage is ideal. It offers ample storage capacity without exceeding airline weight restrictions or becoming too difficult to maneuver. Consider options around 24 to 26 inches, which strike the ideal balance between accommodating your belongings and maintaining ease of use.
I recommend a backpack around 40L-50L. Personally, I wouldn't go over 65L, but some people like a bigger bag. You can always go smaller, but I wouldn't recommend anything smaller than 35L — unless you're into minimalist travel.
The most popular size check-in luggage is 25- to 29-inches tall and various widths. Medium-sized check-in luggage measures 25-26” tall and around 18” wide. * One medium-sized suitcase will generally hold what you need for a week-long getaway.
Bottom Line. Is a backpack a carry on? In many cases, as long as it's not larger than about 55L, yes, you can use many backpacking backpacks as a carry on.
Most airlines allow carry-on luggage that measures up to a maximum of 22 x 14 x 9 inches. In terms of volume, backpacks that are 40-45 liters are good as a carry-on. Anything bigger than that might require you to have it checked in instead.
Ultimately, most 40L or 45L duffel bags will fit as carry-ons, especially the ones (like a duffel bag!) that are soft enough to shift shape slightly. You'll need a very soft, squishy duffel or a small backpack if you plan to use a duffel as an under-the-seat bag.
A 45L bag maximizes overhead space but can get heavy when fully packed; 35L bags tend to be more manageable. Clamshell designs open like a book and are easiest to pack, but bags that open traditionally tend to have more structure.