Osprey Hydraulics

Types of packs

Backpacking packs can be 30 to 70-plus liters. To choose the right capacity, consider trip duration and the gear you’ll bring.

Backpack features
Think about the frame type, location of important pockets, padding and ventilation, among other things.

Backpack fit
Your pack should be correctly sized for your torso length (not overall height) and hip circumference. A fit-expert at an REI store can help.

By Activity

• Hiking: can hold a water reservoir and available in different torso sizes for right fit
• Climbing: narrow profile, abrasion-resistant reinforcements
• Traveling: pockets or compartments for organization, carry-on size

Capacity

• Packs that hold 20L or less are best for runs, day hikes, mountain biking or short trips.
• Packs between 20–35L are great for longer day hikes and as a travel carry-on.
• Packs holding 35–50L work for extended trips and mountaineering or climbing that calls for extra equipment.

Fit

The right daypack fit offers:

• A size appropriate for your torso length (not your overall height)
• A comfortably snug grip on your hips

Choose a gear capacity 

• Runs under 2 hours: 2 liters 
• Runs 2-3 hours: 2 to 6 liters 
• Runs 3-6 hours: 4 to 12 liters 
• Runs over 6 hours: 6+ liters 

Decide on bottles and/or reservoir 

• Most vests are compatible with both bottles and reservoirs. 
• Bottles are easier and faster to refill, usually holding 500 ml of water each. 
• Bottles can be soft or rigid. Rigid bottles are more durable.  
• Reservoirs hold more water, up to several liters. 

Get the right fit 

• Follow the manufacturer’s sizing guidelines. 
• Choose a snug fit. (Measure your chest while wearing your sports bra.) 
• Leave room for adjustment: The straps should sit in the middle of their adjustment range. 
• Women-specific vests offer fits optimized for the bust and shoulders.