What Size Backpack Do You Need in 2021?
This is the most common 
question that comes up when searching for a travel backpack. How much space do you need and how exactly do you convert measurements of liters or ounces into something your familiar with? The first question is easy to answer since you should know how many items you plan to carry around and the size and weight of each. So now you just need to know how this translates into the popular size travel backpacks available today.
Liters vs Cubic Inches in Travel Backpacks
Most popular packs, such
as laptop backpacks, hiking backpacks, and rucksack backpacks all typically list the liter size in the model number. For example, the Osprey Packs Farpoint 70 Travel Backpack previously listed in the Best Travel Backpack 2018 list, is a 70 Liter Backpack.
As a point of reference, it would take 35 2-liter bottles of liquid to fill up the Osprey Packs Farpoint 70 Travel Backpack. That’s quite a lot of room to store items. A smaller size pack, such as a 40L backpack, would be the same capacity of about 20 2-liter bottles of liquid.
The other common measurement of capacity listed for travel backpacks is cubic inches. This tends to be a more accurate depiction of the overall capacity since Liters are often rounded to the nearest 10th for a nice clean number. It looks better to say the Osprey Packs Farpoint Backpack is 70L rather than 4,200 cubic inches. You can always convert cubic inches into Liters to get a more accurate number.
Selecting the Best Size Travel Backpack
As a general rule of thumb
, the following list of sizes is a great place to start when deciding how large of a travel backpack you might need.
- Up to 40L – Small Daypacks designed for quick excursions.
- 30-50L – Overnight Trips designed to carry just a little bit more.
- 40-70L – Weekend Trips designed for extended stays.
- 70L+ – Extended Trips of up to a week or more.
As you can see, it’s often helpful to decide what activity you might be doing in order to gauge which size travel backpack will meet your needs. You can also check out travel guides on how to pack items in a more efficient manner. There are many great ideas out there on maximizing space in small backpacks.
Is a 40L Backpack the Ideal Backpack?
Since most people will 
only be using their travel backpacks for quick day excursions, a 40L Backpack will suit most needs. It will hold several changes of clothes, a laptop, and other small essentials. For those wanting to travel light and minimize the weight they have on their back, then a 40L backpack or less makes perfect sense.
Ultimately when deciding what size travel backpack to purchase comes down to listing all the items you plan on carrying. This will give you a great visualization of what it might take to store all these items and if they are even needed at all. If you are traveling with others, you may even be able to distribute items in a way to reduce the sizes of travel backpacks for everyone involved. Maybe you can even eliminate some things you don’t really even need. I’m sure your back will thank you.
Hiking Backpacks and Other Large Travel Pack Sizes
If day excursions aren’t 
your thing, then you will definitely need a pack that is more substantial than a 40L backpack. This is where the Osprey Packs Farpoint 70L travel backpack and others really shine. They can hold a ton of hiking gear, so minimization really isn’t as big of an issue.
Since the large hiking backpacks will be holding a lot more weight, you’ll want to key in on features that will help you distribute the increased weight on your back and do so in the a comfortable manner.
Pay attention to padded straps. The wider the shoulder straps the better. They will distribute the weight more evenly. Also look for stabilizing belts that will help reduce the shifting of the hiking backpack since it will likely hang a lot lower on your back and can shift if you’re in rough terrain.
If you keep these key aspects in mind, finding a travel backpack that fits the activity you will be doing will be a lot easier.
What Size Backpack for 1 Month Traveling
Traveling for a month or more requires a backpack that is durable and can hold a lot of items. If you’re going to be living out of your backpack, then a larger bag up to 80 Liters is recommended. A smaller backpack like the Osprey Packs Farpoint 40L would be a good choice if you are staying in hostels or hotels where some items will be provided for you.
Traveling for 1 month usually requires around 1-2 weeks of clothes, plus miscellaneous items. Needless to say, clothing will take up the most space. Once way around this is to pack neutral colored clothing that can be mixed and matched easier which can reduce the overall need for more clothes.
When traveling for 1 month, also consider clothing with quick dry material since these types of garments can be washed in a hotel room and they dry out quicker. Ultimately, the best size backpack for 1 month travel is a 70 – 80 L backpack that can store a couple weeks worth of clothing, two pairs of footwear, and any miscellaneous items you may need.
Best Backpack for 3 Month Trip
3 month backpacking trips require tons of clothing and other gear. We recommend searching for the largest backpack you can find and then using packing tips and tricks to minimize your load out as much as possible.
Ideally, you will want to pack 3 weeks worth of clothing that dries quickly and is color neutral. Footwear should be minimized to reduce weight. Other aspects to consider when choosing a 3 month pack include all weather gear to brave the elements and camping gear should you need it.
These factors aren’t as critical if you’re staying in hotels, as a 40L backpack will likely suit your needs. But if you will be living out of your travel backpack for 3 months, it’s best to get the largest backpack you can find.
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