There are a few simple decisions that need to be made in order to determine what kind of pack you need for your trips. These questions will help to guide you in choosing the category of pack you want, and ultimately making a decision about which one you want to get. First you should ask yourself what sort of trip do you like to go on, or if you are preparing for one specific trip, what sort of trip is it? Determining the type of trips will tell you what kind of pack you need.

Extended trips. These packs will be 4,000 cubic inches or larger. They will have really good suspension systems. These packs are excellent at transferring heavy loads through their hip belt, but they are also the largest and heaviest. Normally used on trips that will be more than one week.

Extended weekend. These packs are between 2,000-4,000 cubic inches. This is also the most popular category. options in this category tend to range from about 12 oz-about 4 lbs, and range in suspension from multiple metal stays and a frame sheet, to having no suspension. Because this category varies so wildly you will want to know what feature is most important to you (weight, comfort, pockets, etc.)

Technical daypacks. These packs are smaller packs, that at the biggest might hold enough for an overnight, but are generally for day hikes, not for carrying tents and sleeping bags. These offer tons of features, they are sometimes specialized for specialized activities like mountaineering but there are also some that are designed just for going around town.

Hydration packs. These packs are made for the sole purpose of having water with you. They are equipped with a bladder and a hose system to give you hands free drinking while you are hiking or biking. These usually only have enough room for a few things.

Now you need to choose what is most important to you. Packs are separated into categories based on the features they have:

Minimalist. These backpacks sacrifice everything to save on weight. Their goal is the faster and lighter the better. This is not the pack you should get if you are carrying a heavy load or usually take lots of gear. These are the packs to get if you think one the handle on your toothbrush and the label on your peanut butter are too much to keep.

Ultralight. This means you love saving weight, you'll give up a few things to get there, but you'd still like some suspension, and perhaps a daisy chain too.

Lightweight. These backpacks are the largest category, and offer a host of options. They make use of many weight saving technologies, but give up almost no features, and make basically no design changes to accomplish weight reduction.

Super packer. Super packers are huge and heavy, they are for people who believe that roughing it is nothing. They believe that comfort is number one, and they will bring 2 of everything. These packs offer tons of space and padding and suspension to boot. However it comes at the price of weight and speed.

Once you have decided what you need in a pack, you need to decide what you like in a pack. You need to test some alternatives, and look at different features too. For example, some packs offer exceptionally good ventilation, others amazing compression. See if you prefer external pockets or not. Discover just how much you want to pay. And above all, make sure it fits well.