What size bag is best for backpacking, Your Ultimate Guide to Choosing the Perfect Pack

So, you're bitten by the backpacking bug? That's awesome! Whether you're planning a weekend escape into the wilderness or an epic multi-week adventure, one of the most crucial decisions you'll make is choosing the right backpack. It's more than just a bag; it's your mobile home, your trusty companion, and getting it right can make or break your trip. Let's dive deep into the question: What size bag is best for backpacking?

Understanding Backpack Capacity: Liters are Your Friend

When we talk about backpack size, we're almost always referring to its capacity in liters. Think of liters as the internal volume of your backpack. The more liters, the more stuff you can cram in. But bigger isn't always better, and here's why:

Overpacking: A massive pack can tempt you to bring things you don't need, leading to unnecessary weight.
Discomfort: An oversized pack, even if not fully packed, can be awkward to carry and throw off your balance.
Cost: Larger packs often come with a higher price tag.

The "best" size is highly personal and depends on several key factors. Let's break them down.

Factor 1: Trip Length - How Long Will You Be Out?

This is the most significant determinant of backpack size. The longer you'll be away from civilization (and resupply points), the more gear and food you'll need to carry, and thus, the larger your pack will need to be.

Weekend Trips (1-3 nights): For short excursions, you can get away with a smaller pack.
- Ideal Size: 30-50 liters. This is generally enough for essentials like a sleeping bag, sleeping pad, some food, a stove, water filter, and a few changes of clothes.
- What to Expect: You'll likely be able to pack efficiently and avoid carrying too much extra weight.
Multi-Day Trips (3-5 nights): This is where most casual backpackers find their sweet spot. You'll need to carry more food and potentially extra layers for changing weather.
- Ideal Size: 50-65 liters. This offers a good balance of carrying capacity without being excessively large.
- What to Expect: You'll have room for all your essentials, plus a bit of wiggle room for comfort items or unexpected needs.
Extended Trips (5+ nights to weeks): For longer expeditions, especially in remote areas where resupply is infrequent, you'll need a substantial pack.
- Ideal Size: 65 liters and up. Some expedition-style packs can go as high as 80-100 liters.
- What to Expect: These are for serious hikers who need to carry significant amounts of food, fuel, and specialized gear.

Factor 2: Gear Size and Weight - What Are You Bringing?

The type of gear you use plays a massive role. Are you a minimalist who opts for ultralight, compressible equipment, or do you prefer more robust, comfortable, and potentially bulkier items?

Ultralight Gear: If you've invested in down sleeping bags, compact tents, and frameless packs, you can often fit more into a smaller volume.
Bulkier Gear: If you have a synthetic sleeping bag that doesn't compress as well, or a larger, more comfortable tent, you'll need more space.
Seasonal Considerations: Winter backpacking requires significantly more gear (warmer clothing, bulkier sleeping bags, snow gear), so you'll need a larger pack than you would for summer.

Factor 3: Your Body Size and Fit - The Crucial Element

This is often overlooked but is perhaps the most important factor. A pack that's too large or too small for your torso length will be incredibly uncomfortable, no matter its capacity.

Torso Length: Backpacks come in different torso lengths (short, regular, long). You need to measure your torso to ensure a proper fit. This is not your height, but the distance from your C7 vertebra (the prominent bone at the base of your neck) down to the iliac crest (the top of your hip bones).
Hip Belt and Shoulder Straps: A properly fitting pack will have a hip belt that rests on your iliac crest, transferring most of the weight to your hips. The shoulder straps should hug your shoulders without digging in or leaving a gap.
Women's Specific Packs: Many brands offer women's specific packs, which are designed with different torso shapes, shoulder strap contours, and hip belt angles to better fit the female anatomy.

General Recommendations for the Average American Hiker:

For most American backpackers venturing out for typical weekend or 3-4 day trips, a pack in the 50-65 liter range is usually the sweet spot. This provides enough capacity for essentials without being overly cumbersome.

Don't buy a pack based solely on capacity. A comfortable, well-fitting pack that's slightly too small is infinitely better than a massive, ill-fitting one.

How to Choose the Right Size: A Step-by-Step Approach

Ready to find your perfect pack? Follow these steps:

Determine your typical trip length. Are you mostly doing overnighters or week-long treks?
Assess your gear. Are you a minimalist with ultralight gear, or do you carry more comfort items? Consider seasonal needs.
Measure your torso length. This is non-negotiable for a good fit.
Go to an outdoor retailer and try on packs. Load them up with weight (most stores have sandbags for this). Walk around. Adjust all the straps. Pay attention to how the weight feels distributed.
Don't be afraid to ask for help. Store employees are usually very knowledgeable and can guide you through the fitting process.
Consider the brand and features. Once you have a general size in mind, research different brands and models that offer features important to you (e.g., hydration reservoir compatibility, external pockets, adjustable suspension).

FAQ: Your Backpacking Bag Questions Answered

How do I measure my torso length for a backpack?

To measure your torso length, have a friend help you. Locate the C7 vertebra, the bony protrusion at the base of your neck. Then, find the top of your hip bones, known as the iliac crest. Your friend will use a flexible tape measure to measure the distance along your spine from the C7 vertebra down to the imaginary line connecting the two points of your iliac crest. This measurement, in inches or centimeters, will help you select the correct pack size.

Why is pack fit more important than pack size?

A pack's fit is paramount because it directly impacts comfort and stability. A pack that fits your torso length correctly will distribute the weight primarily onto your hips, taking the strain off your shoulders and back. An ill-fitting pack, even if it's the "right" liter size, can cause chafing, pain, and an unbalanced gait, making your hike miserable. Conversely, a well-fitted pack, even if slightly smaller, will feel much more manageable.

How much should my backpack weigh when fully loaded?

A general rule of thumb is that your fully loaded backpack should not exceed 20% of your body weight. For example, if you weigh 150 pounds, your pack shouldn't weigh more than 30 pounds. This percentage can vary depending on your fitness level and the terrain. It's always a good idea to aim for lighter if possible.

When would I need a backpack larger than 65 liters?

You'd typically need a backpack larger than 65 liters for extended trips lasting a week or more, especially if you're in remote areas with limited resupply options. This also applies to winter backpacking, where bulkier clothing, sleeping bags, and extra gear for snow and cold weather are necessary. Expedition-style trips in harsh environments also demand larger capacities.

Choosing the right backpack size is a foundational step in successful backpacking. By considering your trip length, gear, and, most importantly, your body, you can select a pack that will carry your essentials comfortably and reliably, allowing you to focus on the incredible experiences the trail has to offer.