What this tool is, and who it is for
Pack weight calculators answer a deceptively simple question: is the load on your back actually ultralight, or just lighter than it used to be? The distinction matters because the difference between carrying a 6 kg base and a 12 kg base is felt not as a doubling but as a step change in fatigue over the course of a day. The tool here uses the same base-weight definition the ultralight community settled on: every carried item except food, fuel, water and the pack itself. From there it computes body-weight ratios and frames the result against published thresholds, then layers in the shoulder-loading estimates that come from our instrumented carriage testing.
Used for the ratio classification only.
Everything you carry excluding food, fuel and water. Weigh it rather than estimating.
Food, fuel and anything you consume.
Enter the maximum you would carry at once, not the total for the day.
Determines the estimated load path through shoulders versus hips.
Base weight plus consumables plus water.
Base weight 7.2 kg against a 72 kg body weight.
Ultralight (10%): shed 0.0 kg
Lightweight (15%): shed 0.0 kg
Step-by-step user guide
How to operate the calculator in your browser, what to enter, and what to do with the result.
- 01
Open the calculator and enter your body weight first — every subsequent percentage is calculated against this value.
- 02
Itemise your pack into Base weight (shelter, sleep system, clothing, kitchen, electronics) and Consumables (food, fuel, water) on the form provided.
- 03
Pick the pack construction type closest to yours: frameless, minimal frame, internal frame or full-suspension.
- 04
Read the body-weight ratio band and the shoulder-loading estimate in the result card; these update as you change inputs.
- 05
Use the 'Shed to reach next band' figure as a concrete target for the gear you actually own, not gear you might buy.
What the calculator actually does with the numbers you enter
- 01
Base weight is the total of all carried items excluding food, fuel, water and the pack itself, which is the definition used across the ultralight community.
- 02
Consumables are counted at their average value across the trip, not at day one, so a five-day water carry does not distort the result.
- 03
Body-weight ratio thresholds follow community convention: below 10 percent is ultralight for a base weight, 10 to 15 percent is lightweight, and above 20 percent is conventional.
- 04
Shoulder loading estimates come from our instrumented carriage testing, which measured load distribution at 6 to 20 kg across frameless, minimal-frame and full-suspension packs.
Published sources behind the formulas
- [1]Backpacking base weight philosophy and thresholdsAndrew Skurka · 2025
- [2]Load carriage ergonomics and physiological costApplied Ergonomics · 2024
- [3]Backpack fitting and torso measurement guidanceREI Co-op Expert Advice · 2026
Frequently asked questions
Short, sourced answers to the questions readers send us most often about this calculator.
Should worn weight count toward my base weight?
No. Worn weight (clothes, shoes, sun hat) is excluded from base weight by convention so that two walkers with the same carried load but different carried clothing have comparable scores. Worn weight affects your day in different ways that this calculator does not attempt to model.
Why does my kitchen weight not match the brand's claim?
Manufacturer weights are taken on the lightest available component, often without stuff sack, fuel canister or wind screen. We recommend weighing your actual carried kit on a 1 g scale and entering that figure; it is the only honest number for the model.
What is a realistic base weight for three-season backpacking?
Conventional three-season kit lands between 9 and 14 kg for a beginner and 6 to 9 kg for an experienced walker using lightweight equipment. Below 6 kg means genuinely ultralight and requires both skill and trade-offs in comfort, durability and weather tolerance.
How do I account for food and water?
Enter them separately under Consumables. The calculator averages them across the trip — a 2 kg day-one water carry is not the same as a 0.4 kg average across five days, and the result card reflects that distinction.