Choosing the right size backpack is one of the most important gear decisions when preparing for a backpacking trip. Having a properly fitted pack will make carrying your gear much more comfortable and enjoyable. The wrong size pack can lead to shoulder, neck, and back pain, cause chafing and hot spots, and ultimately ruin your wilderness experience.
Backpacking packs come in a wide range of sizes and designs to accommodate different types of trips and gear loads. You’ll also find more specialized packs for activities like winter camping, alpine climbing, and hydration-focused running and biking. The key is matching your pack size and features to the specific demands of your trip.
Understanding Backpack Sizes
Backpack sizes are generally described in terms of capacity, which indicates the volume of gear the pack can hold. There are two main measurements used:
Liters: The most common measurement used internationally. Standard backpacking pack sizes range from about 20 liters to over 100 liters.
Cubic inches: Used more often in the US. To convert: 1 liter = 61 cubic inches. So a 50-liter pack is around 3,050 cubic inches.
When determining the right pack size, it’s important to consider your gear and trip details first, and then find the corresponding capacity. Just because a 60-liter pack is considered ideal for multi-day trips does not mean it will automatically be the right size for you. Focus on your specific needs and packing style.
Common Size Ranges and Their Uses
Here is an overview of some typical pack size categories and the activities they are designed for:
Daypack Backpacks (15-30 liters / 900-1,800 cubic inches)
Daypacks are great for hikes up to 5-6 hours when you only need to carry the 10 essentials, an extra layer, snacks, and water. Often have minimalist designs with just enough pockets and padding for short trips. May include a sleeve for a hydration reservoir.
Weekend Packs (30-50 liters / 1,800-3,000 cubic inches)
Perfect for 1–3-night camping trips when you need to pack clothing, a sleeping bag and pad, stove, food, and more gear. Streamlined design with enough support and pockets to handle heavier loads.
Multiday Backpacking Packs (50-80 liters / 3,000-5,000 cubic inches)
Built for wilderness excursions ranging from 3-5 nights. Bomber construction and enhanced suspension allow you to carry 7-15 pounds comfortably. Removable lids and spindrift collars allow overflow storage.
Extended Trip Packs (70+ liters / 4,200+ cubic inches)
Cavernous backpacks, in the 5,000+ cubic inch range for weeklong or longer trips. Exotic materials and heavy-duty frames carry the large gear load required when you’re far from civilization. Often feature detachable lid sections and multiple zippered access points.
Specialty Packs
Includes technical alpine and climbing-focused packs optimized for hauling ropes, axes, and bulky clothing. Also includes ultra-running vests designed to carry multiple soft flasks and minimal gear. Youth-specific, women’s specific, and ergonomic packs are also available.
Hydration Packs (1.5-3 liters / 100-200 cubic inches)
Hydration packs are Compact, highly ventilated packs designed to hold a hydration reservoir/bladder and minimal essentials during active pursuits like trail running, cycling, or hiking in hot weather. Focused on external hose routing and fluid access rather than load hauling ability.
Climbing Packs (25-35 liters / 1,500-2,100 cubic inches)
Used for technical ascents and multi-pitch climbing. Extra pockets and daisy chains for hauling gear. Often made with lightweight but super durable materials. Hip belts are removable since climbers use harnesses. Lid and spindrift pocket for quick access to essentials.
Factors Influencing Pack Size Selection
Choosing the right size backpack involves assessing multiple variables including your trip plans, gear, and personal preferences.
Duration of Trip
Not surprisingly, longer trips will require a big pack. The farther you’ll be from civilization, the more food, fuel, clothing, and camping gear you’ll need to carry. Even base weight increases with trip length as you add more consumables and a few extra comfort items. For trips under 3 nights, most people can get by with a pack under 50 liters. Bump up to a 60-80 liter pack for extended 4-7 night trips. And choose an 80+ liter expedition-ready pack for journeys over 1 week.
Gear Volume and Bulkiness
The combined volume and dimensions of your shelter, sleep system, stove, clothing, and other gear play a key role in ideal backpack capacity. Bulky synthetic sleeping bags, two-person tents, and larger cook sets fill more space than lightweight solo shelters, quilts, and alcohol stoves. Assess all your vital gear and determine the pack size that can comfortably fit it all.
Seasonal Considerations
The season you’ll be backpacking will influence how much gear you need to carry. In summer, you can get away with minimal clothing and a tarp shelter to shed rain. But cold weather hiking requires much bulkier gear – think subzero sleeping bags, 4-season tents, puffy layers, and winter boots. Even if trip length is the same, colder temps mean increasing pack size.
Personal Packing Style
Some backpackers run lean and are hardcore about each ounce. But others don’t mind carrying a few extra comfort items or “just in case” equipment. Know your philosophy. Minimalists can get by with smaller sizes, while those who pack heavy or haul photo gear need more space. There’s no right or wrong, only what meets your style.
Body Size and Pack Fit
Torso length plays an important role in getting a proper fitting pack. Shorter torsos need shorter packs, while those over 6 feet tall often size up to longer frame lengths. Hip belt size also impacts ideal capacity, though most belt sizes can be adjusted. Consult sizing guides and measure your body before deciding on pack size.
Proper weight distribution and loading also depend on a pack frame fitting your body type. A 65-liter pack may dig into a petite hiker while feeling perfect for someone taller. Test packs are weighted with gear to assess comfort and fit.
Types of Backpacking Packs
Backpacks fall into three main categories based on their internal frame system and suspension technology:
Frameless Packs
As the name suggests, these packs lack any kind of rigid frame structure. Often used for ultralight hiking and thru-hiking, they are minimalist bags made with lightweight but durable fabrics like Dyneema or X-Pac. Foam padding and minimal straps provide comfort for lighter loads up to 20-25 pounds. Ideal capacity is around 40-55 liters.
Internal Frame Packs
The most popular modern pack design, internal frame packs have a rigid plastic frame sheet and aluminum stays that provide structure, stability, and transfer weight to the hips. Dense foam panels add comfort without the need for a bulky external frame. Perfect for multi-day trips where carrying 30-50 pounds is expected. The main compartment and extendable collar offer 60-80 liters capacity.
External Frame Packs
Rarely seen today except in the hunting community, external frames support the load through an exposed rigid aluminum frame. While not as sleek looking as internal frames, they excel at hauling very heavy loads of meat or camping supplies. Less expensive but durable choice where ultra-lightweight isn’t necessary. Find in sizes ranging from juvenile 20-liter packs up to massive 100+ liter capacity expedition packs.
How to Measure for the Right Pack Fit
The most critical measurement for achieving an ideal and comfortable pack fit is your torso length. This determines the proper frame size you need.
Step-by-Step Guide to Measuring Torso Length
- Stand up straight with your back and shoulders aligned naturally.
- Place a book or carpenter’s square upright on the bony vertebrae protrusion at the base of your neck.
- Let the book or square fall so the lower edge rests on top of your hip bones, keeping your lower back straight.
- Measure from the top ridge of the book or square down to the shelf created at your hip bones. This is your preliminary torso length.
- For fine-tuning, have someone measure from the C7 vertebrae at the base of your neck down to the top of your hip belt on a backpack you’re testing.
- Choose a pack frame size that matches your torso length measurement. Sizes run from extra-short (14-16 inches) up to long (24 inches or more).
How to Determine Hip Belt Size
For proper load transfer to your legs and hips, your pack’s hip belt should wrap around the widest part of your hips with no gaps. Manufacturers design hip belts for S-M-L-sized torsos on corresponding frame lengths. You can further customize the fit by tightening the belt webbing as needed. If your hips measure:
- Under 36″: Go with a size small hip belt
- 36-42″: Choose a size medium
- Over 42″: Opt for a large hip belt
Women may find that unisex hip belts don’t properly accommodate the curve of their hips. In those cases, a pack with a women’s specific hip belt is ideal for comfort.
Adjusting and Fitting Shoulder Straps
Ideally, the shoulder straps on your pack will sit comfortably on your trapezius muscles without any pinching. Follow these tips for a good fit:
- Straps should be 2-3 inches apart at the collarbone to distribute weight
- Strap padding should end 1-2 inches below the armpits so the range of motion isn’t limited
- With the pack on, you should be able to fit your open hand between the strap and shoulder bone
- Straps can be adjusted both for length and angle to fine-tune fit
- Use load lifters if available to pull the pack closer to your shoulders
Additional Considerations
Beyond size and fit, also assess these factors when choosing your backpacking pack:
Load Distribution and Pack Weight
A key goal in pack selection is evenly distributing weight so that your legs and core carry most of the load rather than your shoulders and back. An adjustable suspension system, sternum strap, and padded hip belt all help you dial in a comfortable carry. Seek out packs known for great load transfer.
Also consider the pack’s weight, as you have to carry that too! Lightweight but durable materials can pare pounds without sacrificing durability. Focus on packs under 3 pounds to avoid adding unnecessary heft.
Accessibility and Pockets
Consider how you like to organize and access your gear when backpacking. Do you want lots of exterior pockets and stash points? Look for a pack with daisy chains, hip belts, and shoulder strap storage. Or do you prefer packing cubes and bags within a cavernous main interior? Seek out a large panel loader opening. External lash points for tools like ice axes are also useful if needed.
Hydration Systems Compatibility
Many but not all packs come with dedicated sleeves and ports for hydration reservoirs and their tubing. If you plan to use a hydration bladder, ensure your pack is designed to accommodate it. Make sure the location of the reservoir won’t throw off your pack’s center of gravity.
Attachment Points for Gear
Some packs feature special loops, bungees, ice axe holders, and pickets for lashing on bulky items like sleeping pads, tent bodies, or rope. If you’ll be hauling equipment externally, search for a pack with ample exterior attachment points.
Balancing the Load
Strive to pack your heaviest gear close to your core, keeping the volume centered above your hips. Use the middle of the pack for dense items like food, stove fuel, cook kits, shareable gear, and your sleeping bag. Surround those with your sleeping pad, tent, and clothing layers. Place lighter items like your sleeping quilt, puffy, and rain layers towards the top and outer pockets.
Tips for Packing Gear Efficiently
Packing the right gear, the right way is highly important if you are traveling long distances for multiple days. Here are a few tips to help you pack better and more efficiently:
- Lay all your gear out on the floor and categorize the items into the least heavy, medium-weight, and heaviest.
- Pack the items that are lightweight and will not be needed frequently first.
- Pack heavier items afterward, and place them in the middle of the backpack so these rest on your waist. This helps in dividing the weight. This item can include, a ration, hydration pack, and other heavy equipment.
- Pack frequent-use items in the last, this will help you easily access these items without having to search for them.
- Use an accessory pocket to store a map, bug repellant, ID, and headlamp.
- Try to carry items that you can double use, for example, a cup can also be used in an eatery bowl.
- Pack water outside of the bag if possible, this helps in easy access to the water multiple times throughout the journey.
- Once, the backpack is completely packed make sure to try it on and walk a little. If you feel anything out of place, uncomfortable, or feel load misbalance, try rearranging the items and try on the backpack by carrying it again.
Note: Do not hang items outside the backpack, this can lead you to miss your balance.
Utilizing Compression and Packing Cubes
Take advantage of compression straps to cinch down bulky sleeping bags and pads. Use lightweight nylon packing cubes to organize clothing, food, and toiletries within your pack. Soft-sided cubes protect items while maximizing space efficiency. Consider using a foldable duffel as a liner for your main compartment to waterproof gear and simplify packing.
Essential Items to Include
Be sure to leave room for important accessories like microspikes, snowshoes, mosquito head nets, rain fly & ground sheet, water filter/purifier, first aid supplies, repair kit, gloves, warm hat, and navigation/signaling items like map, compass, and whistle. You may need these items readily accessible when conditions demand.
Conclusion
While pack sizing involves many factors, focus first on your projected trip plans and gear volume needs. Seek out a backpack with a capacity that fits your intended load, along with adjustable components to customize the fit. Field test potential packs are weighted down to mimic your typical carry. Finding the right size backpack that is comfortable, has great features, and is lightweight will ensure you enjoy many happy trails!
FAQs
What is the ideal capacity for an everyday backpack?
For most hiking and travel daypacks, a capacity of 20 to 35 liters is considered ideal. This range offers enough space to accommodate your essentials, including clothing, food, and extras like a camera or a book.
How do you determine the right backpack size for your needs?
Choosing the right backpack size depends on your intended use:
Under 10 to 20 liters: These backpacks are perfect for carrying everyday basics, optimal for light loads, and accommodating 13-inch laptops.
20 to 40 liters: Designed for handling larger workloads and weekend getaways. Best suited for students and capable of holding 15- to 16-inch laptops.
50 to 80 liters: Ideal for hikers and campers tackling longer adventures.
Should size up or size down when selecting a backpack?
If you are carrying a lot of gear or plan to go on extended hikes, you should size up. Conversely, if you’re carrying just a few essentials or going on a short hike, a smaller backpack will suffice.
How does backpack sizing work?
Backpack sizing is primarily based on torso length, which means you choose a backpack size that matches your torso measurement. Keep in mind that this choice also dictates the size of the accompanying hip belt.
What size backpack is best for international travel?
A 45-liter backpack is the largest size allowed as a carry-on for most US airlines. For international or budget airlines, opt for a bag under 40 liters. If you aim to pack ultralight, a backpack of 35 liters or less is acceptable for virtually any airline.