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When you start researching thru-hiking, you’ll quickly encounter the term “Big Three.” This refers to the three heaviest and most important pieces of gear you’ll carry: your backpack, your shelter, and your sleeping system. Together, these items typically account for half or more of your base weight (the weight of your pack without food, water, or fuel).
Understanding the Big Three is crucial because these items have the biggest impact on your comfort, your pack weight, and ultimately your success on the trail. Make smart choices here, and you’ll thank yourself with every mile.
Why the Big Three Matter
The Big Three matter for two critical reasons: weight and comfort. Every ounce you carry gets multiplied by every step you take over hundreds or thousands of miles. A pack that’s five pounds lighter means less strain on your knees, feet, and back. It means you can hike farther with less fatigue and recover faster at the end of each day.
But weight isn’t everything. The cheapest ultralight gear won’t help if it leaves you cold, wet, or uncomfortable. The key is finding the balance between weight, durability, and comfort that works for your body, your budget, and the specific trail you’re hiking.
Your Backpack: The Foundation
Your backpack is literally what holds everything together, but here’s the counterintuitive part: you should choose your backpack last. That’s because the right pack depends entirely on the volume and weight of everything else you’re carrying.
Capacity is measured in liters, and most thru-hikers use packs between 40 and 65 liters. If you’re going ultralight with minimal gear, a 40-50 liter pack works beautifully. If you’re carrying more traditional gear or hiking in colder seasons, you’ll need 55-65 liters. Bigger isn’t always better because extra space tempts you to fill it with things you don’t need.
Torso length matters more than your height. Backpacks are sized by the length of your back from your C7 vertebra (the bump at the base of your neck) to the top of your hip bones. Most outdoor retailers can measure this for you. A properly fitted pack transfers weight to your hips, not your shoulders.
Weight capacity is crucial. Pack manufacturers specify how much weight their packs can comfortably carry. Ultralight packs (under 2 pounds) typically max out around 25-30 pounds total weight. Traditional packs (3-5 pounds) can handle 35-45 pounds. Choose a pack rated for your expected total pack weight (base weight plus food and water).
Features to consider include hip belt pockets (invaluable for snacks and your phone), water bottle pockets you can reach while wearing the pack, and external attachment points for wet gear. Some hikers love packs with top lids and lots of pockets, while ultralight enthusiasts prefer simple roll-top designs.
Popular choices include the Osprey Exos/Eja series, Granite Gear Crown3, ULA Circuit, and Zpacks Arc Haul. Expect to spend $200-400 for a quality thru-hiking pack.
Your Shelter: Your Home on the Trail
Your shelter protects you from rain, wind, insects, and morning dew. The main options are tents, tarps, and hammocks, each with distinct advantages.
Tents are the most popular choice because they offer complete protection and are easiest to set up. Freestanding tents stand up without stakes, making them versatile on any terrain including wooden platforms. Non-freestanding tents require stakes or trekking poles but are typically lighter. Double-wall tents have a separate mesh inner and waterproof fly, offering better ventilation and less condensation. Single-wall tents combine everything into one layer, saving weight but often creating more interior moisture.
For thru-hiking, look for a tent weighing 2-3 pounds (solo) or 3-4 pounds (two-person). A two-person tent split between partners is often lighter per person than two solo tents. Key features include good ventilation, a vestibule for gear storage, and a bathtub floor that extends several inches up the walls.
Popular tents include the Big Agnes Copper Spur, Zpacks Duplex, TarpTent ProTrail, and Nemo Hornet. Budget $250-600.
Tarps are the ultralight option, often under 1 pound. They require practice to pitch properly and offer less bug and weather protection, but they’re incredibly versatile and provide excellent views. Most tarp users pair them with a bug bivy or mesh insert.
Hammocks work wonderfully in forests and eliminate the need to find flat ground. A complete hammock system (hammock, suspension, bug net, and tarp) typically weighs 2-3 pounds. The downside is they don’t work above treeline or in many desert sections where trees are scarce.
Your Sleeping System: Rest and Recovery
Your sleeping system has two main components: your sleeping bag or quilt and your sleeping pad. Together, they determine whether you sleep comfortably or shiver through the night.
Sleeping bags have zippers and hoods, fully enclosing you. Quilts eliminate the back insulation (which gets compressed under you anyway) and save significant weight, typically 1-2 pounds for a three-season quilt. Quilts attach to your sleeping pad to prevent drafts.
Temperature rating is critical. Most thru-hikers use a 20°F quilt for three-season hiking. If you sleep cold, size down 10 degrees. If you sleep hot, you might get away with 30°F. Remember that temperature ratings assume you’re wearing a base layer and hat and using a good sleeping pad.
Insulation type matters too. Down insulation offers the best warmth-to-weight ratio and compresses smaller, but loses insulation when wet and costs more. Synthetic insulation retains warmth when damp, dries faster, and costs less, but weighs more and is bulkier. For trails with frequent rain, synthetic or treated hydrophobic down makes sense.
Quality quilts from Enlightened Equipment, UGQ, or Katabatic run $300-450. Budget sleeping bags from REI or Big Agnes cost $200-350.
Sleeping pads provide both cushioning and critical insulation from the cold ground. The R-value measures insulation (higher is warmer), and you want at least 3.0 for three-season hiking. Foam pads like the Therm-a-Rest Z-Lite are nearly indestructible, cost under $50, and double as pack frames, but offer minimal cushioning. Inflatable pads are far more comfortable and warmer but can puncture and cost $150-250. Many hikers love the Therm-a-Rest NeoAir Xlite NXT or Nemo Tensor for their balance of weight, warmth, and comfort.
Putting It All Together
For reference, here are realistic Big Three weights:
Ultralight setup: 6-9 pounds (sub-2lb pack, 1-1.5lb shelter, 1.5-2lb sleeping system)
Lightweight setup: 10-14 pounds (3-3.5lb pack, 2-3lb shelter, 2.5-3.5lb sleeping system)
Traditional setup: 15-20 pounds (4-5lb pack, 4-5lb shelter, 3-5lb sleeping system)
Your goal should be a Big Three total that keeps your overall base weight under 20 pounds, ideally closer to 15 pounds. This makes a dramatic difference in your daily energy and injury prevention over a long thru-hike.
Making Your Choices
Don’t rush these decisions unless your open to returns and delays. Visit outdoor retailers to try on packs with weight in them. If possible, borrow or rent gear for a weekend shakedown hike. Read reviews on websites like REI, watch video reviews, and ask questions in thru-hiking forums.
Remember that the “best” gear is the gear that works for your body, your budget, and your hiking style. A slightly heavier setup that keeps you comfortable and confident is far better than ultralight gear that leaves you cold or anxious.
The Big Three represent your biggest investment in thru-hiking, both financially and in terms of comfort. Take your time, do your research, and choose wisely. Your feet, back, and future trail self will thank you.