Trips of 5 days or more usually call for packs of 70 liters or more. These are also usually the preferred choice for winter treks lasting more than 1 night. (Larger packs can more comfortably accommodate extra clothing, a warmer sleeping bag and a 4-season tent, which typically includes extra poles.)

For a one-week trip in 2026, the ideal backpack size is generally between 35 and 45 liters. A 40-liter pack is widely considered the "sweet spot" because it is large enough to fit 5–7 days of clothing (using packing cubes), a pair of spare shoes, and toiletries, yet small enough to meet the carry-on dimensions for most major airlines (typically 55 x 40 x 23 cm). If you are a minimalist traveler or traveling in a warm climate with light fabrics, you could drop down to a 28–32 liter pack. Conversely, if you are traveling in winter and need bulky sweaters or jackets, a 45–50 liter pack might be necessary, though this often requires checking the bag on budget airlines like Ryanair or Spirit. To maximize space, choose a "front-loading" (clamshell) design rather than a "top-loading" hiking pack, as it allows you to access your items more like a suitcase. Always check the harness system, as carrying 10kg for a week requires a supportive hip belt to prevent shoulder strain.