Several factors are involved when you want to pick the correct backpack size, for example, the length of your trip, the type of travel, and the items you need to bring. Here are some guidelines to help you choose the correct size for you. 1. Daypacks - backpacks that are designed for short trips or day excursions. Daypacks have a capacity of 20-35 liters. It's a compact and lightweight backpack making it easier to maneuver or carry its user. 2. Weekend Trips - if you are going on a weekend trip, you will need a backpack with a 40-60 liters capacity. This bag size will allow you to carry all your essentials, clothes, personal items, and gear. 3. Extended Trips - for those trips longer than a weekend, you may need a backpack of 60-85 liters capacity. This bag size will help provide enough storage for all your essential items, clothes, food, and gear, such as your sleeping bag or camping equipment. 4. Multi-day backpacking - if you plan to go backpacking for several days, you will need a backpack with a capacity of 70 liters or more. This bag will give you enough space to bring your clothes, gear, food, water, and shelter. The size of your backpack for camping should be based on what you need and the camping trip you are taking. This would ensure that your backpack is efficient, comfortable, and fits you well for a shorter or longer period.