How much food do you need? How heavy will your pack be? Enter your trip details and we'll estimate your calorie needs, food weight, and total starting pack weight.
The calculator starts with your trip length and the average calories burned per day at your chosen intensity. Easy flat terrain averages around 2,500 calories a day. Moderate hiking runs closer to 3,000. Strenuous alpine routes with big elevation and thin air regularly push 3,500 to 4,000 calories.
From that calorie target, the calculator converts to food weight using caloric density — the number of calories packed into each ounce. A standard backpacking food mix (bars, instant meals, trail mix) averages around 110 calories per ounce. If you're going ultralight with dehydrated meals and nut butter, you can push that to 130 cal/oz. If you're bringing heavier real food, budget closer to 90 cal/oz.
Total calories = days × intensity (cal/day) Food weight (oz) = total calories ÷ caloric density (cal/oz) Total pack weight = base gear + food weight + water weight The total pack weight calculation only appears when you add base gear and water in the Advanced Options. Those numbers are personal — your sleep system, shelter, clothing, stove, and water strategy vary too much to estimate for you.
Most grocery store backpacking food lands in the 100 to 120 cal/oz range. Nut butters, olive oil, and dark chocolate are the outliers — closer to 160 to 180 cal/oz — and serious ultralight packers lean hard on them. Fresh vegetables, canned goods, and anything with high water content drop well below 90 cal/oz and add weight fast. If you're building a custom food list, weigh your food and divide calories by ounces. The 110 default is a reasonable starting point for most trips.
Glacier National Park requires bear canisters throughout the backcountry. Many wilderness areas in the Bob Marshall, Beartooth, and Absaroka-Beartooth require or strongly recommend them as well. A standard BV500 holds roughly 100 cubic inches of food, which works out to about 7 days of food for one person depending on packaging bulk. If your trip multiplies out to more than 7 person-days, plan for multiple canisters or a larger canister like the BV475 or Garcia.
Bear boxes are available at some high-use trailheads, but you can't count on them being open or at your specific campsite. Don't plan a trip around infrastructure you haven't confirmed.
There's no universal "right" pack weight, but a common rule of thumb is to keep your total load under 20–30% of your body weight. On rough Montana terrain — loose talus, sustained grades, high altitude — the lower end of that range makes a real difference by day two. Ultralight setups with base weights under 10 pounds make it much easier to stay within that window even on longer trips.
Water is often underestimated. Two liters weighs 4.4 pounds. On a hot day with long stretches between sources, you might carry three liters or more. Factor that in before you head out, and know your water sources.
These estimates use a moderate intensity (3,000 cal/day) and standard mix caloric density (110 cal/oz).
| Days | 1 Person | 2 People | 4 People |
|---|---|---|---|
| 2 days | 3.4 lbs | 6.8 lbs | 13.6 lbs |
| 3 days | 5.1 lbs | 10.2 lbs | 20.5 lbs |
| 5 days | 8.5 lbs | 17.0 lbs | 34.1 lbs |
| 7 days | 11.9 lbs | 23.9 lbs | 47.7 lbs |
| 10 days | 17.0 lbs | 34.1 lbs | 68.2 lbs |
Most backpackers need between 1.5 and 2.5 pounds of food per day, depending on caloric density and exertion level. On moderate terrain, plan for around 3,000 calories per person per day. On strenuous alpine routes, that climbs to 4,000 calories or more. Using high-calorie dehydrated foods (around 130 cal/oz) keeps pack weight down; fresh or heavy food (around 90 cal/oz) adds significant weight fast.
A typical backpacking pack weighs between 25 and 45 pounds when loaded for a multi-day trip. Base gear weight (shelter, sleep system, clothing, stove) usually runs 10 to 20 pounds for a traditional setup, or under 10 pounds for ultralight. Add food weight (roughly 1.5 to 2 lbs per day), water weight (2.2 lbs per liter), and any extras. Most hikers aim to keep total pack weight under 30% of body weight.
Bear canisters are required in some areas of Montana and strongly recommended across most of the backcountry. Glacier National Park, portions of the Bob Marshall Wilderness, and many Beartooth-area trailheads require hard-sided canisters or approved bear-resistant storage. Even where not required, hanging food is increasingly ineffective due to bear conditioning. A standard BV500 canister holds roughly 7 person-days of food. Plan accordingly for longer trips or larger groups.
Caloric density is the number of calories per ounce of food. It matters because every ounce you carry costs energy and pack weight. Ultralight dehydrated meals and nut-based foods run around 130 calories per ounce. A standard mix of backpacking food (bars, instant meals, some snacks) averages around 110 cal/oz. Fresh produce, canned goods, and anything with high water content drop well below 90 cal/oz and add weight fast. Higher caloric density means you carry less weight for the same energy, which adds up fast on a week-long trip.
Most outdoor medicine and sports science guidelines suggest keeping total pack weight under 20–30% of your body weight. For a 160-pound person, that's a 32 to 48 pound ceiling. On rough Montana terrain with significant elevation gain, erring toward the lighter end makes a real difference by day two. Ultralight backpackers aim for a base weight under 10 pounds so total loaded weight stays manageable even with several days of food and water.
Heading out for a day hike instead? Use the Hiking Time Calculator to estimate how long your hike will take based on distance and elevation gain.