What this tool is, and who it is for
Food is the heaviest thing most backpackers carry and the most under-planned. This estimator solves the problem the way a physiologist would: take your activity profile, multiply by an appropriate MET value, adjust for pack weight, gradient and cold, then divide by the energy density of the food you actually plan to eat. The output is in kilocalories per day and grams per day at three realistic densities. It is a planning tool, not a dietary prescription, and the limitations panel flags that distinction clearly.
Dehydrated meals sit near 4.0 kcal/g, nut and oil mixes near 5.0, added oils near 6.0.
Walking expenditure plus four non-walking waking hours at rest rate.
612 g per day at 5.0 kcal/g.
Pack and cold adjustments applied: ×1.08 pack, ×1.00 cold.
Carbohydrate: 383 g/day — primary fuel at moderate to hard effort.
Fat: 119 g/day — the highest energy density available.
Protein: 115 g/day — higher intakes support recovery on multi-day efforts.
Step-by-step user guide
How to operate the calculator in your browser, what to enter, and what to do with the result.
- 01
Enter your body weight and the trip duration in days. Most trip planning errors start here — round up, because you will eat more than you think.
- 02
Choose the activity profile: easy day, long day, climbing day or expedition day. Each has a different MET value applied.
- 03
Set your pack weight and the typical gradient for the day — the calculator adjusts both automatically.
- 04
Pick a cold exposure level. Even mild cold adds 5 to 15 percent to the requirement through thermoregulation.
- 05
Read daily kilocalories, then read the food weight at each of three densities. Plan against the middle figure unless you have a specific reason not to.
What the calculator actually does with the numbers you enter
- 01
Energy expenditure is estimated from MET values multiplied by body mass and duration, the standard approach used in the Compendium of Physical Activities.
- 02
Load carriage and gradient increase the MET value; the model adds an allowance rather than treating all walking as equivalent.
- 03
Cold exposure adds an energy cost through thermoregulation, modelled as an increment above the activity value in low temperatures.
- 04
Food weight is derived from total kilocalories divided by energy density, using 4.0 kcal per gram for dehydrated meals, 5.0 for nut and oil rich mixes, and 6.0 for added fats and oils.
Published sources behind the formulas
- [1]Compendium of physical activities — MET valuesArizona State University / ACSM · 2024
- [2]Nutrition and energy requirements in the backcountryWilderness Medical Society · 2024
- [3]Energy density and weight of backcountry foodBackpacking Light · 2025
Frequently asked questions
Short, sourced answers to the questions readers send us most often about this calculator.
How many kcal per gram for backpacking food?
Most commercial dehydrated meals sit around 4.0 to 4.5 kcal per gram as packaged. Add nuts, oil, cheese or butter and you can reach 5.0 to 6.0. Pure sugar is 4.0, fat is 9.0. A reasonable target is a daily average of 4.5 to 5.0 kcal per gram across the whole pack.
Do I need to factor cold?
Yes. Below about 5 degrees Celsius, the body burns noticeably more to maintain core temperature, and below freezing the increment is meaningful. The calculator adds 5 to 15 percent depending on the temperature range you choose. In sustained cold, plan for the higher end.
What about heavy exertion days?
Use the climbing day or expedition day profile and the result will be substantially higher than a normal day. Most backpackers under-eat on heavy days and over-eat on rest days, which is the wrong way around. Front-load calories for the days you will actually work hard.
Should I eat before or during exercise?
Both. About 200 to 400 kcal an hour during effort is realistic for sustained multi-hour work, with carbohydrates dominant. The calculator gives total kilocalories per day; distribute them across eating occasions rather than concentrating them at the end of the day, when appetite at altitude often collapses.