Hiking Backpack Sizing

What size hiking/camping backpack do you need?

The capacity of a backpack is measured in cubic inches (cu. in.) or liters. (One liter equals about 61 cubic inches.) Many backpacks come in two or three sizes to fit different torsos, so capacity is usually for the middle size. You will notice that many backpacks have a number, such as 65, in their model name. This refers to the approximate volume in liters. A 65-liter pack has a volume of approximately 4,000 cubic inches.

To choose the best backpack for your needs, consider the trips you plan to take. Extended backpacking in very cold areas requires bulkier, warmer gear plus more food. At the other extreme, you need much less space for gear and food for weekend hikes in warm weather. The traditional solution is to buy several backpacks of different sizes, but you can see why reviews recommend a 4,000-cubic-inch backpack as the best compromise.

For a warm-weather weekend trip -- 2,000 to 4,000 cu. in.

For a longer or cold-weather trip -- 4,000 to 7,000 cu. in.

Consider your gear and packing style too. It's possible to buy a down-filled summer sleeping bag that packs down to the size of a teacup, and alcohol stoves are tiny. Ultralight backpackers need a lot less volume. If you plan to buy the very lightest camping items, experts say you can likely get by with a volume of 2,440 to 2,750 cu. in. for a warm-weather weekend trip, or about 4,000 cubic inches for a longer trip.

If you want the most versatile pack, reviews recommend a backpack with about 4,000 cu. in., but make sure it has excellent compression for smaller loads. You can also start with the gear you have, and figure the volume you need.

Also consider your attitude toward backpack longevity. Reviews note that there's some tradeoff between weight and durability. Do you want to invest in a backpack you'll use for a decade or longer, even if this comes at the cost of carrying some extra weight all these years? Mainstream backpacks often carry lifetime guarantees, while ultralight backpacks are guaranteed against manufacturers' defects but not against tears in use.

Ultralight backpacks are best on trails or in open land, away from thorns and rocks. Many ultralight backpackers don't mind the idea of replacing a backpack that wears out, saying the extra comfort of carrying fewer pounds is well worth it. Also, ultralight backpacks seem to be evolving at a faster rate than most backpacks - adding durability and convenience while minimizing weight -- so you're more apt to want to trade up to a newer model.