Trails & Trip Guides Questions, Answered
8 researched, fact-checked answers to the questions hikers ask most about trails & trip guides.
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In plain English
Picking a pack for a trip is like packing a suitcase for a vacation. The longer you go, the more you bring, until you reach a place where you can restock. On long trails, hikers walk into towns every few days to buy food, so the pack only needs to hold food for the next stretch.
Some places add their own rules. In parts of bear country you must carry your food in a hard plastic container, which takes up a lot of room. In the desert, water is the heavy item, because there may be no stream for many miles.
On every trip, short or long, carry a small set of safety items often called the Ten Essentials: things like a map, a light, extra food and water, a warm layer and a first-aid kit. They are there for the day something goes wrong.
Food and water decide the size of long trips
The week-long and three-day answers turn days into liters using roughly 1.5 to 2.5 liters of pack space per day of food. That is a hiking rule of thumb, and so are pound-per-day food figures. The best-known published energy numbers, 3,400 to 4,300 kcal a day, come from military research on cold-weather field work, not backpacking.5 Research on endurance events also shows a ceiling: sustained energy use plateaus below about three times basal metabolic rate, and spending more than about 2.5 times draws down body stores.6 On a long trip, more food than that is hard to use anyway.
Water is usually the heaviest single item. A liter weighs about 1 kg.7 Guadalupe Mountains National Park works an example: a three-day, two-night trip at a gallon a day means about 24 lb of water.1
Canister routes change the math
The thru-hike answer notes that canister routes like the John Muir Trail push pack size up. The rules behind that are specific to each park. In Yosemite, all food, drinks, trash and toiletries must be stored, and hanging food is illegal everywhere in the park.2 Sequoia and Kings Canyon require containers from May 1 to October 31 in named areas such as the Rae Lakes Loop and Dusy Basin, and highly recommend them elsewhere.3 Inyo National Forest applies food storage rules year-round in all its wilderness areas.8
Size matters for the pack. Glacier Bay's loaner canister is 560 cubic inches, about 9 liters, holds roughly six days of food for one person and weighs 2.8 lb.9 Rules change, so check the current regulations for your route before you choose a pack.
Desert hiking: water, heat and timing
The desert answer says water needs often run 4 to 6 or more liters between refills. For comparison, Guadalupe Mountains advises a gallon, a little under 4 liters, per person per day, at about 8 lb.1 Grand Canyon rangers say hikers in heat can lose one to two quarts of water an hour, recommend salty snacks, and note that most heat-illness rescues involve people hiking between 10 a.m. and 4 p.m.10 The CDC also suggests doing outdoor activity in the coolest parts of the day when heat risk is high.11
Know the warning signs. The National Weather Service lists confusion, slurred speech and a body temperature above 103°F as signs of heat stroke, a severe emergency: call 911 or get the person to a hospital immediately.12
The 20% line on overnight packs
The overnight answer says the loaded pack should stay under roughly 20% of body weight. That figure has no primary source; it is a hiking-community rule of thumb. Deuter says people can carry a maximum of 20–25%, and Appalachian Trail hikers in one study actually carried about 25% (men) and 28% (women).13,14 A study of long-distance hikers found foot pressure rising clearly once packs passed about 10% of body weight.15 Lighter is better, but there is no single safe line.
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