What Size Backpack Do I Need?

Feb 17, 2023

Man with backpack climbing a hill.

As an Amazon Associate, Modded gets commissions for purchases made through links in this post.

Exploring the outdoors is an American pastime as old as baseball. Is there any better way to connect with nature and exercise simultaneously? Whether on a hike at a state park or backpacking through western Europe, half the battle of planning is packing. You may ask, “What size backpack do I need?” This guide on backpacks will guide your decision.

Ask These Questions

The trip you’ve planned is getting closer each day, so it’s time to consider what backpack you need. The size of your gear will differ based on a few factors, such as:

  • Location: The first question to ask is where you’re going. More specifically, how is the weather going to be at your destination? Suppose you’re backpacking through the Guadalupe Mountains in Texas. The climate will be mild compared to a trip to Denali National Park in Alaska. Lighter clothes mean you’ll need less space, so you can pack less or make room for other stuff.
  • Length: Another factor to consider is how long your trip is. You won’t need a large bag if you’re going for a weekend. A day trip will call for an even smaller bag, depending on what you need to bring. However, a weeklong or month-long expedition requires a heavier set of luggage.
  • Packing: The size of your backpack is essential, but it’s also crucial to consider how you pack. Are you a minimalist? Can you get away with two extra shirts, trousers and hygiene products? Or will you load everything you possibly need? If you’re conscious about how you pack, you can save space and get away with a lighter backpack.

Different Backpack Sizes

Before you buy a backpack, understand that companies measure backpacks in liters. So you’ll need to break out the metric system notes from grade school. Backpacks start around 10 liters and climb to 70 liters or more. The size you get will determine how much you can pack and how heavy the bag will feel on your back while hiking.  

What Size Backpack Do I Need?

Now it’s time to start looking for backpacks. You should base your bag decision on the factors mentioned above and pick the one best for your travels. Consider how your bag will suit you on this trip and others in the future. Here are four categories of backpacks based on how many liters they hold.

1. 10 Liters or Smaller

The most compact backpacks have a capacity of 10 liters or fewer. These bags are ideal for children who need a light load while traveling. They’re also terrific for adults if you’re going on a day trip and know you’re coming back home on the same day. These backpacks are practical if you’re doing recreational activities like a sporting event or need a small bag for an extra pair of clothes, hygiene products and a phone charger. 

2. 10 to 30 Liters

The next step up in backpacks is the 10 to 30-liter capacity. These backpacks are the more traditional kind you’d see someone walk around a college campus with. You can use gear in this category for school, work commuting or camping trips. 

This backpack category is ideal for day trips like the smaller bags above. Their design suits you if you plan on spending the day hiking. They’re large enough to carry a day’s worth of supplies. However, they’re light enough for adults to carry all day while on the trail. 

3. 30 to 50 Liters

If those knapsacks aren’t big enough, it’s time to graduate to the 30 to 50-liter category. You may consider these backpacks as medium-sized bags. They’re the ones you’ll typically see hikers wear while on the trails. Their design is practical for multi-day trips. Sometimes, a weekend getaway is all you need to feel reinvigorated. A 30-liter bag can hold the essentials like emergency kits, food and hygiene supplies. These backpacks are best for trips between one and three days.

4. 50 Liters and Up

The last category is for the big kahuna. If you’re going on an extended hike, these backpacks are the ones for you. Have you seen “The Amazing Race” on CBS? On the show, contestants race worldwide with these bags on their backs. 

A 50-liter backpack is ideal if your trip will last a week. Anything longer needs a 70 or 80-liter bag. These backpacks are best for those going on long hikes. Some trails in the US take a month or longer to navigate. For example, the Continental Divide Trail runs from New Mexico to Montana. The trek is 3,000 miles long and requires five months or more to walk the entire trail. You’ll surely need a large backpack for that feat.

What Size Backpack Do I Need?

Backpacking is a fun adventure many people undertake annually. The fresh feeling of nature refreshes your mind and body like nothing else. One thing you’ll need to consider on your trip is the packing. You may ask, “What size backpack do I need?” Use this guide for your decision.

Stay up to date with the latest by subscribing to Modded Minute.


Jack Shaw is a senior writer at Modded. Jack is an avid enthusiast for keeping up with personal health and enjoying nature. He has over five years of experience writing in the men's lifestyle niche, and has written extensively on topics of fitness, exploring the outdoors and men's interests. His writings have been featured in SportsEd TV, Love Inc., and Offroad Xtreme among many more publications.