By Michael Reynolds, Hiking Guide
Michael Reynolds is a hiking guide and outdoor instructor who helps people plan day hikes, backpacking trips, and longer trail adventures. His knowledge includes selecting appropriate hiking gear, adjusting backpacks for a good fit, and assisting hikers in preparing for various distances, terrains, and weather situations. He provides basic guidance that makes outdoor preparation easier for both beginner and expert hikers.
A hiker preparing for a weekend trek may stand in an outdoor store, looking at 30L, 40L, 50L, and 65L backpacks and wondering which number is most important. The answer is determined by factors other than the distance traveled. Hiking backpack size should correspond to both the amount of stuff you need to carry and the measurements of your body.
For a short day hike, a 15-30L pack may suffice. Overnight and multi-day trips demand additional capacity, but buying the largest pack available is not always the best option. A well-fitted 40L pack can be more useful than an unwieldy 65L pack stuffed with superfluous items.
The optimal hiking backpack size is determined by two factors: capacity and fit. Choose capacity based on your gear and trip length, and then select a physical pack size based mostly on your torso length and hip measurement.
Backpack Size Means Two Different Things
When individuals discuss backpack size, they frequently refer to two different metrics.
Capacity refers to how much the backpack can hold, which is commonly measured in liters. A 20L pack contains significantly less storage space than a 60L pack.
Physical size refers to how well the backpack fits your body. Manufacturers often provide alternative torso lengths or adjustable suspension systems to ensure that the pack sits properly on your back.
These two metrics must not be confounded.
You may need a 50L backpack if your vacation includes a tent, sleeping bag, food, clothing, and cooking supplies. However, this does not imply that you must always choose a “big” physical pack size. The correct torso size is determined by your body dimensions and the manufacturer’s sizing chart.
REI specifically recommends using torso length rather than overall height when determining backpack fit, while manufacturers such as Gregory also use torso length and hipbelt measurements to determine fit.
That distinction is one of the most important things to understand before buying.
Hiking Backpack Size by Trip Length
Trip duration provides a useful starting point for choosing capacity, but it is only a starting point. The amount of equipment you carry can change the answer considerably.
Current pack guidance from Gregory places short hikes and day trips around 18–30L, overnight and weekend trips around 35–50L, and extended backpacking around 55–75L or more. REI’s guidance similarly shows that backpack capacity increases with the length and gear demands of the trip.
| Trip type | Approximate capacity | Typical use |
| Short day hike | 10–20L | Water, food, light layers, essentials |
| Full-day hike | 20–30L | More food, water, clothing and safety gear |
| Overnight | 30–50L | Shelter, sleeping system, food and clothing |
| 2–3 days | 40–60L | Multi-day gear and additional supplies |
| Extended trip | 55–75L+ | Larger food, clothing and equipment load |
These ranges are not rules. A lightweight backpacker carrying compact equipment may use a smaller pack than someone carrying bulky traditional gear.
Weather also matters. Cold-weather clothing, a larger sleeping bag, extra insulation, or additional safety equipment can take up substantially more room than summer gear.
What Size Backpack Do I Need for a Day Hike?
For many day walks, 15-30L is a reasonable range, with the exact quantity determined by distance, weather, hydration requirements, and how much equipment you bring.
According to REI, 10-20L daypacks are suitable for shorter, simpler trips, whereas larger daypacks are useful for hikes that cross mealtimes or entail shifting temps. Gregory similarly positions many day-trip packs between 18 and 30 liters.
A short, two-hour walk in warm weather may require little more than:
· Water
· Snacks
· Phone
· First-aid supplies
· Light layer.
· Sun Protection
A full-day mountain hike could take far more.
You might need:
· Extra clothing
· Additional food
· Add more water
· Navigation equipment
· A headlamp
· Rain protection
· Emergency supplies.
That is why selecting a daypack based purely on the number of hours spent on the trail might be misleading.
A beneficial rule
Choose the smallest pack that can comfortably hold the things you actually need for the conditions.
A smaller pack might prevent needless packing, but it should never require you to abandon critical safety items.
For a practical day hike packing list, consider the trail first, then the backpack.
[INTERNAL LINK NEEDED: day hike packing list]
What Size Backpack Do I Need for a 2–3 Day Hike?
For a typical 2-3 day backpacking trip, 40-60L is a good starting point, however skilled lightweight hikers may need less, while bulky gear or colder circumstances may require more.
Gregory presently recommends 50-65L for multi-day trips lasting 2-4 days, with various pack-sizing recommendations varying according to equipment volume.
Consider what should fit inside the pack:
• Tent or shelter
• Sleeping bag or quilt
• A sleeping pad
· Food
• Water
• Cooking equipment
• Extra clothing
• Rain Gear
• First-aid supplies
• Navigation and emergency equipment.
The crucial question is not simply, “How many days will I hike?”
Ask instead:
“What loudness does my entire gear system require?”
For example, a lightweight summer setup may fit well into a 40-50L pack. A three-day journey in colder weather, with heavier insulation and more supplies may push you to 55-60L.
35L, 50L, or 65L Backpack: Which Should I Buy?
These three capacities address many of the decisions that hikers encounter.
35L backpack
A 35L backpack is suitable for:
• Long day walks.
• Minimize overnight trips.
• Warm-weather fast packing.
• Hikers using compact equipment.
Its primary advantage is lesser volume and less temptation to carry superfluous stuff.
Its constraint is simple: large sleeping systems, tents, food, and clothing can quickly devour available space.
50L Backpack
A 50L backpack is one of the most adaptable options for hikers who want to use their pack for numerous purposes.
It can be used for:
• Long-distance hikes requiring heavy equipment.
• Overnight outings.
• Weekend backpacking.
• Suitable for light 2-3 day vacations.
For someone looking for their first backpacking pack, 50L can be a good compromise assuming their kit fits within.
65L backpack
65L backpacks offer ample space and are suitable for:
• Multi-day tours.
• Bulky equipment.
• Cold-weather backpacking.
• Longer journeys
• Traditional hiking setups.
The disadvantage is that increased space may encourage over packing. A larger pack may also become heavier once full.
Which one is right?
| Pack | Best suited to | Main advantage | Main limitation |
| 35L | Day hikes/minimal overnights | Compact | Limited space |
| 50L | Overnight/weekend trips | Versatile | May be tight for bulky gear |
| 65L | Multi-day/bulky loads | More capacity | Easier to overpack |
If your stuff fits comfortably in a 50L pack, there’s usually little reason to carry a 65L pack only for the extra space.
How to Select the Ideal Backpack Size for Your Skill Level
Your experience level does not exactly impact the size of your backpack, but it does influence how much gear you bring.
Beginner hikers
Beginners often carry more because they are still figuring out what they actually need.
A 20-30L daypack can hold all of your essential day-hiking gear without taking up too much space.
For overnight trips, a 45–60L pack may provide a comfortable starting point while you learn how your gear fits together.
Experienced Hikers
Experienced hikers often know exactly what they need for a particular route.
Someone who has reduced the size and weight of their shelter, sleeping system, clothing, and cooking equipment may be comfortable with a smaller-capacity pack.
This does not mean experienced hikers should automatically use smaller packs. The correct choice still depends on the trip.
Cold-Weather Hikers
Cold conditions can require significantly more bulky equipment.
Extra layers, insulation, gloves, hats, warmer sleeping systems, and other seasonal equipment can increase volume quickly.
For winter trips, capacity should be based on the complete equipment list rather than a standard summer backpacking recommendation.
How to Measure Your Torso for a Hiking Backpack
Your torso length is generally more important than your overall height when selecting the physical size of a backpack.
REI’s fitting method uses the distance between the C7 vertebra at the base of your neck and the iliac crest at the top of your hip bones.
You can measure it with help from another person.
Step 1: Find Your C7 Vertebra
Tilt your head forward.
Feel for the prominent bony point at the base of your neck. This is the C7 vertebra and marks the upper point of the measurement.
Step 2: Find Your Iliac Crest
Place your hands on your hips with your thumbs pointing backward.
The top of your hip bones marks the lower reference point.
Step 3: Measure Between the Two Points
Have another person measure from the C7 vertebra down to the line connecting the top of your hip bones.
Use that measurement against the manufacturer’s sizing chart.
Do not assume a medium from one brand will fit exactly like a medium from another. REI notes that torso ranges vary by manufacturer and model, so the specific pack’s chart should always take priority.
How Should a Hiking Backpack Fit?
A properly fitted backpack should feel stable without creating painful pressure points.
The hipbelt should sit around your hip bones rather than hanging low around your waist. REI’s current daypack guidance recommends positioning the top edge of the hipbelt roughly one finger width above the top of your hips, then checking how the shoulder straps contact your back.
When adjusting a backpack, start with the hipbelt.
1. Position the Hipbelt
Place it securely around your hips and tighten it comfortably.
2. Adjust the Shoulder Straps
Pull the shoulder straps until they sit comfortably against your shoulders without forcing the pack excessively into your back.
3. Adjust the Load Lifters
If your backpack has load-lifter straps, adjust them according to the manufacturer’s instructions to bring the upper pack closer to your body.
4. Check the Sternum Strap
The sternum strap should help stabilize the shoulder straps. It should not be tightened so aggressively that it restricts breathing.
5. Walk With Weight Inside
Never judge a backpack only while it is empty in a store.
Put some representative weight inside and walk around. Bend, climb stairs if possible, and move your arms.
Look for:
• Excessive shoulder pressure
• Hipbelt slipping
• Pack movement
• Rubbing
• Unusual pressure on your lower back
A pack that feels comfortable empty can feel very different when loaded.
How Much Weight Should You Carry?
There is no single backpack weight that is safe or comfortable for every hiker.
Your body, fitness, experience, terrain, distance, and pack design all matter.
The practical goal is to carry what you need without adding unnecessary weight.
For beginners, this means avoiding the temptation to fill every available pocket.
A larger backpack does not make a heavier load easier. It only provides more space.
The pack’s suspension system also matters. Heavier loads generally benefit from a more supportive frame and hipbelt, while lightweight loads may work well with simpler designs. Gregory similarly distinguishes between streamlined packs for lighter missions and structured packs for heavier loads.
How to Pack a Backpack Efficiently
Knowing how to pack a backpack can make a smaller pack much more useful.
Start by separating equipment into groups:
• Sleeping gear
• Cooking equipment
• Clothing
• Food
• Emergency equipment
• Frequently used items
Then consider how often you will need each item.
Put Frequently Used Items Where You Can Reach Them
Keep items such as:
• Snacks
• Water
• Rain jacket
• Map
• Phone
In exterior pockets or areas that are easy to access.
Keep Dense Items Close to Your Back
Items with more weight should generally be positioned close to your body’s center rather than hanging far away from your back.
This helps the load feel more stable while walking.
Protect Items From Weather
A pack’s capacity is not the same thing as its waterproof rating.
If rain is possible, protect clothing, sleeping equipment, electronics, and other sensitive items using appropriate waterproof bags or the pack manufacturer’s recommended system.
A rain cover can provide another layer of protection, but it should not be treated as a guarantee that everything inside the backpack will remain completely dry.
Don’t Choose Your Backpack Before Choosing Your Gear
One of the easiest mistakes is buying a 65L pack first and then filling it.
If you already own your major equipment, lay it all out before choosing a backpack.
Measure or estimate the volume of:
• Sleeping bag
• Tent
• Sleeping pad
• Clothing
• Food
• Stove
• Cooking equipment
Then consider how much additional space you realistically need.
This approach can lead to a smaller and more efficient pack.
It also prevents you from buying a backpack that is much larger than your actual equipment requires.
Common Backpack Sizing Mistakes
Choosing by Height Alone
Two people who are the same height can have different torso lengths.
Fix: Measure your torso and use the manufacturer’s size chart.
Buying the Largest Pack “Just in Case”
Extra capacity often becomes extra gear.
Fix: Estimate your actual equipment volume first.
Ignoring the Hipbelt
Shoulder straps should not carry the entire load.
A properly fitted hipbelt helps transfer load toward the hips. REI says the majority of a backpack’s weight should be supported by the hips when the pack is correctly fitted.
Testing an Empty Backpack
An empty pack can hide fit problems.
Fix: Try it with representative weight.
Forgetting Seasonal Differences
A summer pack may not hold your winter equipment.
Fix: Choose capacity around the conditions of your most demanding regular trips, or use different packs if your trips vary greatly.
How Backpack Fit Can Affect Comfort on the Trail
A poorly fitted pack can become a problem over a long day.
Rubbing from shoulder straps or a loose hipbelt can create hot spots that become painful as mileage increases. If you are trying to prevent blisters hiking, remember that feet are not the only area affected by poor equipment fit.
Before a longer trip, take a properly loaded backpack on shorter walks.
Check for:
• Heel or foot irritation
• Shoulder rubbing
• Hipbelt pressure
• Lower-back discomfort
• Hot spots
• Pack movement
Fix problems before the major trip rather than hoping they disappear after several hours on the trail.
Frequently Asked Questions
Which size pack is right for a day hike?
A 10-30L pack is what you will see for most day hikes. For short and simple hikes 10 20L may be enough, but for multi day hikes which include extra food, water, layers of clothing and safety gear we see that 20 30L is what is used. What you choose really does depend on the trail and weather as well as what you will be bringing with you.
What kind of backpack do I need for a 2-3 day hike?
A 40-60L pack is what we recommend to start for 2 to 3 day trips. With light gear you may do fine with less capacity, also if you are going for cold weather or want that traditional bulky gear you may end up using more. Pack size should be determined by your full equipment list and not just trip duration.
Is a 35L backpack large enough for an overnight trip?
It is the case that which also happens to play out should you go with compact gear and find yourself in mild weather. A 35L pack does not do well with bulkier items like sleeping bags, clothing, or shelter which means it is best for hikers that know what they will fit in that space.
Is your 50L backpack sufficient for a weekend?
For instance on short to medium duration weekends trips which aren’t of a great exertion level. A 50L pack is a good compromise between what it can carry and how easy it is to wear. For winter use, with more gear, or when you require packing in lots of food and water that number goes up.
Is a 65L backpack too big?
Also at times a 65L pack does fit for multi day trips, cold weather gear, or when you have bulkier items to carry. That said we see people choose the 65L which they think is better in terms of space and then they fill it with unneeded stuff.
Does backpack size depend on height?
The fit of a backpack is not to be determined by height alone. Torso length is the key measurement in which to base your choice of pack size and also which the manufacturers use to put forward specific torso length ranges for each model.
How do I determine that my hiking pack is the right fit?
The hip belt should fit snugly at the hips, the shoulder straps should make good contact without too much pressure, and the pack should stay put when you move. Before you buy the backpack try it out with the weight it will carry and follow the manufacturer’s instructions for adjustment.
Should I get a different pack for each hike?
You can, also find that one pack may not fit all situations. For short hikes a 20-30L day pack may be what you’re looking for, but for multi day trips a 50-65L backpacking pack is the way to go. If your hiking varies greatly we recommend you to own packs that are suited to their specific use.
Do I have a hiking pack that will work for travel?
Some of the best hiking packs for travel are those which have panel access and great organization. Also it is important to note that travel and hiking pack designs are very different. Hiking packs mainly focus on what is comfortable for the user on the trail, while travel packs may put more so on easy access, luggage like organization, and laptop storage.
How do I increase the capacity of my small hiking backpack?
Instead of just packing everything in tighter, identify what is bulky or redundant and get rid of that, at the same time use compact gear and improve overall organization. Put out what you use the most in the outer pockets and put the heavy equipment near your back. Also do not remove your safety gear to save space.
Final Thoughts
Capacity is a function of your gear, fit is an issue of your body. For day hikes which go the distance a 20-30L pack may be what you require, and for multi night and weekend trips a 40-60L pack is a good play. For longer or gear heavy adventures you may want to look at 55-75L and up.
Before purchase make out a practical list of what you do have, look at the weather and length of your trips, and compare your equipment volume to that of the backpack’s capacity. Also measure your torso and refer to the manufacturer’s fit chart which is a better guide than using height as the sole determinant of size.