What Size of Backpack for Backpacking: Finding Your Ideal Volume

Table of Contents

1. Introduction
2. The Basics of Backpack Volume
3. Backpack Size by Trip Length
4. How Your Gear Choices Dictate Pack Size
5. Beyond Liters: Understanding Torso Size and Fit
6. Step-by-Step: How to Measure Your Torso at Home
7. Weight Capacity vs. Volume Capacity
8. Pack Features That Help Manage Size
9. Practical Loading Techniques
10. Choosing the Right Pack for Specialized Use
11. Conclusion
12. FAQ

Introduction

You are standing in your living room with a pile of gear spread across the floor. You have your sleeping bag, a tent, a stove, and enough food for three days. The problem is your current pack looks like it might burst at the seams before you even reach the trailhead. Or perhaps you have the opposite problem: you bought a massive expedition pack for a simple overnight trip, and now you are carrying five pounds of empty fabric and unnecessary straps. Choosing the right pack size is a fundamental skill that separates frustrated hikers from prepared outdoorsmen.

At BattlBox, we know that your pack is the foundation of your entire kit. If the volume is wrong, your gear won't fit or your load will be unstable. If you want gear curated for that kind of loadout, get expert-curated gear delivered monthly. This guide covers how to choose the right volume based on your trip length, gear bulk, and activity type. We will also look at how to ensure the pack actually fits your body. Finding the right balance ensures you carry exactly what you need without being weighed down by extra space.

The Basics of Backpack Volume

When people ask about backpack size, they are usually talking about volume. In the outdoor industry, volume is almost always measured in liters (L). This measurement represents the total capacity of the main compartment plus any functional side pockets or lid compartments.

A 20L pack is roughly the size of a standard school backpack. A 85L pack is a massive hauler designed for weeks in the wilderness. Understanding these numbers is the first step in organizing your EDC (Everyday Carry) or your backcountry setup. For a deeper breakdown, see our guide to backpacking pack size.

Quick Answer: For most backpackers, a 40–50 liter pack is the "sweet spot" for weekend trips (1–3 nights). If you are heading out for a week or more, look for a 60–75 liter pack to accommodate extra food and supplies.

Backpack Size by Trip Length

The primary factor in choosing a pack size is how many nights you plan to spend outside. More nights mean more food, more fuel, and more clothing layers.

Day Hikes and Short Excursions (10L – 25L)

These packs are designed for trips where you return home or to a base camp by sunset. They are often called daypacks. They provide enough room for the essentials: a hydration bladder (a plastic water reservoir with a drinking tube), a lightweight rain shell, a small first aid kit, and snacks. A waterproof first aid kit is a smart add-on for this kind of loadout.

• 10L - 15L: Ideal for trail running or mountain biking where you only need water and a windbreaker.
• 20L - 25L: The standard for a full day hike. This size fits a warm layer, a lunch, and a comprehensive emergency kit.

Overnight and Weekend Trips (30L – 50L)

This is where backpacking truly begins. To fit a sleep system and shelter into a pack this size, your gear needs to be relatively compact. A Rockagator Hydric Series 40-Liter Waterproof Backpack is a solid example of a pack built for that kind of carry.

• 35L: Works for minimalist overnighters in warm weather. You will likely need to strap your sleeping pad to the outside.
• 45L - 50L: This is the most popular size for two-night weekend trips. It offers enough room for a tent, a sleeping bag, a stove, and a couple of days' worth of food without requiring expert packing skills.

Multi-Day Trips (50L – 70L)

When you are heading into the woods for 3 to 5 nights, your gear requirements increase. You need more food and perhaps a water filtration system. A VFX All-In-One Filter can help keep that side of your kit simple. These packs feature more robust suspension systems to handle the increased weight.

• 55L - 65L: The industry standard for traditional backpacking. Most beginners should start here as it is forgiving of bulkier, budget-friendly gear.
• 70L: Good for trips in cooler weather where you need to carry extra insulation or a heavier four-season tent.

Extended Expeditions (70L and Up)

These packs are for trips lasting a week or more, or for specialized missions like mountaineering. They are also common for parents who end up carrying gear for their children. For bigger hauls, start with the Camping Collection.

• 80L+: These are heavy haulers. They are designed to carry 50 pounds or more. You should only choose a pack this large if you are carrying professional equipment, winter camping gear, or supplies for a group.

How Your Gear Choices Dictate Pack Size

Two people going on the same three-day trip might need completely different pack sizes. This is because the volume of your gear is just as important as the number of items.

The "Big Three" Impact

The "Big Three" refers to your shelter, sleep system, and the pack itself. These items take up the most space. For a deeper field-tested look at those essentials, read Backpacking the BattlBox Way: What Every Backpacking Trip Needs.

1. Sleeping Bags: A high-quality down sleeping bag might compress to the size of a loaf of bread. A cheaper synthetic bag might be the size of a large watermelon.
2. Tents: Ultralight trekking pole tents take up very little room. Traditional dome tents with heavy fiberglass poles are much bulkier.
3. Sleeping Pads: Inflatable pads fold down small, while closed-cell foam pads are bulky and usually must be strapped to the exterior of the pack.

Food and Water

Food is the most variable part of your pack volume. Freeze-dried meals in pouches are compact and light. Canned goods or fresh food take up significant space and add weight. Additionally, if you are hiking in an area that requires a bear canister (a hard-sided, bear-proof container), you must ensure your pack is wide enough to fit that rigid cylinder inside. If water is the variable, build around the Water Purification collection.

Seasonal Considerations

Summer gear is small. A lightweight quilt and a bug net don't take up much room. In the winter, you need a thicker sleeping bag, a heavy parka, extra fuel to melt snow for water, and more robust traction for your boots. When conditions get colder, the Fire Starters collection matters even more. Winter backpacking usually requires jumping up one full size category (e.g., moving from a 50L to a 65L pack).

Key Takeaway: Don't buy a backpack until you have most of your other gear. It is much easier to buy a pack that fits your gear than to try and force your gear to fit a pack that is too small.

Beyond Liters: Understanding Torso Size and Fit

While volume tells you how much gear the pack can hold, torso size tells you if the pack will fit your body. A 65L pack that is too long for your back will cause the weight to pull away from your shoulders, leading to back pain and fatigue. If you want another angle on sizing before you buy, check out What Size Bag Do I Need for Backpacking?.

What is Torso Length?

Torso length is the distance from your iliac crest (the top of your hip bones) to the C7 vertebra (the prominent bone at the base of your neck when you tilt your head forward). It has nothing to do with your height. A tall person can have a short torso, and a short person can have a long torso.

Why Fit Matters

Backpacks are designed to carry about 80% of the weight on your hips. The hip belt should wrap around the top of your hip bones, not your waist. If the pack is the wrong size, the hip belt will sit too high or too low, forcing your shoulders to carry the load. This is a recipe for a miserable trip. Once you know your load range, choose your BattlBox subscription so the gear keeps matching the pack.

Step-by-Step: How to Measure Your Torso at Home

You can easily measure your torso with a flexible measuring tape and a friend's help. Knowing this measurement allows you to shop for packs with confidence.

Step 1: Locate your C7 vertebra. Tilt your head forward and feel for the bony bump where your neck meets your shoulders. This is your starting point.

Step 2: Find your iliac crest. Put your hands on your hips with your thumbs pointing toward your spine. Imagine a line connecting your two thumbs across your back. This is your end point.

Step 3: Measure the distance. Have a friend measure the vertical distance along the curve of your spine from the C7 vertebra down to that imaginary line between your thumbs.

Step 4: Check the manufacturer’s size chart. Most brands offer packs in Small, Medium, or Large based on these measurements. For example, a "Medium" torso is often between 18 and 20 inches.

Weight Capacity vs. Volume Capacity

It is possible to fill a 40L pack with 50 pounds of lead weight. While the volume fits, the suspension system (the frame, stays, and padding) will likely fail. Every pack has a recommended load range.

• Lightweight Packs: These may have a volume of 50L but are only designed to carry 25–30 pounds comfortably. They use thinner materials and lighter frames.
• Workhorse Packs: These are built with heavy-duty internal frames (metal or plastic stays that provide structure) and can handle 50+ pounds.

If you carry heavy, traditional gear, do not buy an ultralight pack just to save weight. The pack will sag, and the straps will dig into your skin. Always match the weight of your kit to the manufacturer's load rating.

Pack Features That Help Manage Size

Sometimes you need a pack that can "shrink" or "grow" depending on the trip. Look for these features to increase the versatility of your pack.

Compression Straps

Most quality packs have straps on the sides. These allow you to cinch down the pack when it isn't full. This keeps the load close to your center of gravity and prevents gear from shifting around while you walk.

Floating Lids

The "lid" or "brain" of a backpack is the top compartment. A floating lid is attached with adjustable straps rather than a fixed hinge. This allows you to extend the lid upward to secure a bulky item (like a rope or a foam pad) between the lid and the main compartment.

External Lash Points and MOLLE

MOLLE (Modular Lightweight Load-carrying Equipment) is a system of webbing loops common on tactical and bushcraft packs. It allows you to attach extra pouches, knife sheaths, or tool rolls to the outside. For more on the blades and saws that often ride on those packs, see 12 Heavy-Duty Bushcraft Knives and Saws for the Wild.

Expansion Shrouds

Many top-loading packs have an extension of fabric at the top called a spindrift collar. If you have an unexpectedly large load, you can fill this extra space and secure it with the drawstring.

Practical Loading Techniques

The way you pack your bag can make a small pack feel larger. Learning to use every cubic inch of space is a skill that comes with practice.

• Stuff, Don't Fold: Clothing takes up less room when stuffed into the gaps between larger items rather than being folded into flat rectangles.
• Remove Packaging: Take food out of bulky boxes and put it into plastic zip-top bags. This removes air and wasted space.
• Nested Gear: Put your stove and fuel inside your cooking pot. An Überleben Stöker | Stove - Ultralight Titanium is a good example of gear that stays compact.
• The Bottom Layer: Place your sleeping bag at the very bottom. It provides a cushioned base for the rest of your gear and doesn't need to be accessed until you reach camp.

Note: Never put heavy items like water or food at the very top or very bottom of the pack. Keep the heaviest items centered and close to your spine for the best balance.

Choosing the Right Pack for Specialized Use

Not every backpacking trip is a standard trek on a groomed trail. Different activities require different pack philosophies.

Bushcraft and Survival

If you are practicing bushcraft, you are likely carrying heavy steel tools like axes, saws, and fixed-blade knives. You might also carry a heavy canvas tarp rather than a lightweight nylon tent. For these trips, the Bushcraft collection is the right next step. A pack with high-denier (thicker) fabric and external attachment points is better than a lightweight trekking pack. A 45L to 55L rugged pack is usually sufficient for a few nights of bushcraft.

Hunting

Hunting packs need to carry your gear in and, ideally, help you carry meat out. These often feature an external frame or a "load shelf" that allows you to sandwich heavy loads between the frame and the pack bag. Because of the weight of the meat, the Hunting & Fishing collection is the place to start even for shorter trips.

Emergency Preparedness

When building a "Go-Bag" or "Bug-Out Bag," you want a pack that is ready to move. The Emergency / Disaster Preparedness collection is a strong fit for that kind of loadout. A 30L to 40L pack is usually the limit for most people to carry comfortably over long distances during an emergency.

Bottom line: Your pack should be the last thing you buy. Once you have your gear, you can accurately measure its total volume and weight, then select a pack that supports that specific load.

Conclusion

Selecting the right backpack size is about understanding the relationship between volume, weight, and your body's geometry. A pack that is too small leads to gear being left behind or dangerously lashed to the exterior. A pack that is too large adds unnecessary weight and can become a disorganized mess. Most hikers find that a 50L pack is the most versatile starting point for weekend adventures.

As you progress in your outdoor journey, your gear will likely become lighter and more compact. You might eventually find that you can fit a three-day trip into a 35L pack. The key is to start with what you have, measure your torso for a proper fit, and practice packing before you hit the trail. If you want a pack-and-gear setup that keeps pace with your goals, start your BattlBox subscription.

Our mission at BattlBox is to provide you with the gear and knowledge to step into the wild with confidence. Whether you are looking for a compact daypack for your EDC or a rugged hauler for your next expedition, we curate the best equipment to help you get there. Preparation is the bridge between a survival situation and a successful adventure.

• Step 1: Gather all the gear you intend to carry.
• Step 2: Measure your torso length to ensure the pack frame fits.
• Step 3: Choose a volume based on your trip length (e.g., 50L for 3 days).
• Step 4: Test the fully loaded pack on a short walk before your trip.

Adventure. Delivered.

FAQ

What size backpack do I need for a 3-day trip?

For a typical 3-day (2-night) backpacking trip, a 40 to 50-liter backpack is usually ideal. This provides enough space for a tent, sleeping bag, pad, stove, and food. If your gear is older or bulkier, you might want to move up to a 60-liter pack to ensure everything fits inside. For a compact backup ignition option, the Pull Start Fire Starter is a useful add-on.

Can a backpack be too big for backpacking?

Yes, a pack that is too large can be detrimental because it adds unnecessary weight and often leads to "load creep," where you pack extra items just because you have the space. An oversized pack can also be unstable if the compression straps can't tighten the load sufficiently, causing the weight to shift while you walk. If you want a step-by-step packing refresher, read How to Properly Pack a Bug Out Bag.

Is a 40L backpack big enough for backpacking?

A 40L backpack is sufficient for experienced backpackers with lightweight, compact gear or for anyone going on a minimalist overnight trip in warm weather. If you have a high-quality down sleeping bag and a small tent, 40L can easily work for a weekend. For a pocket-sized light that stays useful beyond the trail, a Powertac SOL LED Rechargeable Keychain Light is a smart EDC choice.

How do I know what size backpack fits my frame?

To find the right fit, you must measure your torso length from your C7 vertebra to your iliac crest. Most backpack manufacturers provide a size chart that correlates this measurement to their pack sizes (Small, Medium, Large). Once you have the pack, ensure the hip belt sits on your hip bones and there are no gaps between the shoulder straps and the top of your back. For another sizing reference, see What Size Bag Do I Need for Backpacking?.