The weight of your backpack will vary throughout your journey. You should use a medium-sized bag (50-65 liters or 3100-4100 cubic inches) to carry your layers of clothing to adjust to changing temperatures throughout the day. The porters and yaks carrying your larger duffel bags may sometimes move slower than you and usually leave earlier in the morning. The items you bring daily should primarily be for inactivity rather than hiking. This may include a jacket and hat for the early morning, a camera and notebook for recording your impressions during breaks, and so on. It is not advisable to bring a smaller pack to carry less weight. Slightly larger packs distribute the weight on your back better and are easier to pack, especially with cold fingers.