Ultralight Backpack Buying Guide: How to Choose the Right Pack

Quick Answer

Choose an ultralight backpack by first estimating your total trail weight (base weight plus consumables). If your base weight is under 10–12 pounds, a frameless pack like the Murmur 36 saves significant weight; otherwise, opt for a framed pack for comfort. Always prioritize torso fit and hip belt placement over brand or style.

When you're ready to lighten your load, the ultralight backpack is the centerpiece of your kit. But with so many options, how do you choose the right one? This buying guide breaks down the key decisions: frameless vs. framed, pack volume, and fit. We'll give you concrete rules so you can pick a pack that matches your trip and body.

The right ultralight backpack doesn't just save weight—it improves your hiking experience by reducing strain and increasing agility. Whether you're a weekend warrior or a thru-hiker, understanding your needs before you buy will save you money and frustration.

Frameless vs. Framed Ultralight Backpacks

The biggest decision is whether your ultralight backpack has a frame. Frameless packs, like the Gossamer Gear Murmur 36, are the lightest option—some weigh under a pound. They work best when your total pack weight stays under 15–20 pounds, because without a frame, the pack transfers load directly to your shoulders. For example, the Murmur 36 weighs just 7.9 ounces, making it ideal for minimalists who have trimmed their base weight.

Framed packs add a few ounces but provide better load transfer to your hips, which is crucial for heavier loads or longer resupplies. If your base weight is above 12 pounds or you're carrying more than a few days of food and water, a framed pack will be more comfortable. Many ultralight framed packs still weigh under 2.5 pounds, so you don't have to sacrifice much weight for support.

• Weigh your fully loaded pack before a long trip to see if you're within the comfort range of your pack.

Pack Volume: How Many Liters Do You Need?

Pack volume is the next consideration. For day hikes or minimalist overnighters, a 20–30 liter pack is often enough. For multi-day trips, you'll likely need 30–50 liters. The key is to match volume to your gear and trip length. If you're using compression sacks and packing cubes, you can often get away with a smaller pack.

For example, the Gossamer Gear Vetta 20L Daypack is a roll-top design that offers expandability and easy access, perfect for day trips or as a summit pack. If you're going on a longer trip, a 36-liter pack like the Murmur 36 can handle a few days of gear if you pack efficiently. Always consider your sleeping bag and tent volume, and leave room for food and water.

Fit and Sizing: Getting the Right Torso Length

A well-fitting pack is essential for comfort and injury prevention. Measure your torso length (from the C7 vertebra to your iliac crest) and compare it to the pack's size range. Most ultralight packs come in small, medium, and large, but some are one-size-fits-all. The hip belt should sit on your hip bones, not your waist, and the shoulder straps should wrap comfortably without gaping.

When trying on a pack, load it with 10–15 pounds to simulate real conditions. Adjust the load lifters and sternum strap to see how it feels. A pack that fits well will feel like part of your body, not a burden. If you're between sizes, prioritize torso length over hip belt size, as you can often swap hip belts.

Key Features to Look For

Ultralight backpacks often come with minimal features, but some are worth their weight. Look for stretch mesh pockets for water bottles and gear, like the Murmur 36's UHMWPE Stretch Mesh front pocket. This allows you to access items without stopping. Shoulder strap pockets are also handy for keeping your phone or snacks close at hand.

Consider the pack's closure system: roll-tops are waterproof and compressible, while drawstrings are lighter but less weather-resistant. Also, check for attachment points for trekking poles or an ice axe. Finally, think about the fabric: lightweight materials like ALUULA are waterproof and durable but can be pricey. Weigh the benefits against your budget.

Decision Rules for Choosing an Ultralight Backpack

• Estimate your total pack weight: Weigh your base gear (excluding consumables) and add 2 pounds per day for food and water. If your total is under 20 pounds, a frameless pack works; if over, choose a framed pack. Know your weight before you buy.
• Match volume to trip length: Day hikes: 20–30L. Overnight: 30–40L. Multi-day: 40–50L. Use packing cubes to compress gear and reduce volume. Smaller pack encourages lighter packing.
• Get the right torso fit: Measure your torso and use the manufacturer's size chart. The hip belt should sit on your hip bones. Load the pack and adjust straps for a snug, comfortable fit. A good fit prevents pain and improves balance.

Products That Fit This Guide

• Murmur 36 Hyperlight Backpack: The latest restock has been updated with a UHMWPE Stretch Mesh front pocket. In the pursuit of lightness, every detail matters. That’s why you can now hike with our infamously light Murmur, now even lighter at 7.9 ounces, in the cutting-edge waterproof ALUULA Graflyte V52 fabric. Unlike traditional laminates, ALUULA is made from a 100% polyethylene fused at the molecular level—no adhesives, coatings,... This pack is a top choice for ultralight enthusiasts who want a frameless pack under 8 ounces. The stretch mesh pocket offers easy access, and the waterproof fabric protects your gear without a rain cover.
• Vetta 20L Daypack: Seize the day with a pack up for the task: the Vetta 20L Daypack. Its cult-classic roll-top design makes packing quick and seamless, paired with water bottle pockets, stretch mesh front pocket, shoulder strap pockets keep your essentials ready in seconds. Simple, rugged, and up for the challenge. The Vetta 20L Daypack is built for Type II Fun that loops back to the car. For day hikes or as a travel daypack, the Vetta 20L offers a roll-top closure that expands for extra gear. The multiple pockets keep essentials organized and accessible, making it a versatile addition to any quiver.

Is an Ultralight Backpack Right for You?

Best for

• Hikers with a base weight under 10–12 pounds who want to minimize pack weight
• Those doing short trips or fast-and-light missions where agility matters more than load capacity
• Travelers who need a packable daypack for exploring after arrival

Not for

• Hikers carrying heavy loads (over 20 pounds) or needing to carry lots of gear for extended trips
• Those who are new to backpacking and may not have refined their gear to be lightweight
• Anyone who prioritizes maximum comfort over weight savings

Choosing an ultralight backpack comes down to knowing your weight, trip length, and body. Start with a frameless pack if you're a gram-counter, but don't shy away from a framed model if you need support. Use the decision rules above to narrow your options, and always test the pack with weight before you commit. Happy trails!