Short answer
Base weight is everything in or on your pack except consumables: food, water and fuel. Worn clothing and pocket items are excluded. In the worked ledger, base weight is 5,700 g. Adding 4,630 g of consumables gives a total pack weight of 10,330 g, and adding 1,200 g worn gives a skin-out weight of 11,530 g. The categories are a bookkeeping choice, not a standard.
Base weight is the weight of everything carried in or on the pack, except consumables: food, water and fuel. Worn clothing and items in pockets are left out of it. Total pack weight adds the consumables back in, and skin-out weight adds the worn items. Each of the three numbers answers a different question, so compare packs using the same definition each time.
What counts toward base weight
Base weight includes the shelter, sleep system, pack, kitchen, water containers and treatment, clothing carried but not worn, electronics, essentials and an other category for anything that does not fit. The essentials category covers first aid, navigation, repair and light. Water is counted through its containers, not its contents, so an empty bottle or a filter belongs in base weight and the water inside it does not.
Fuel is a consumable. An empty fuel canister counts under the kitchen, and the fuel inside it counts as a consumable.
What base weight leaves out
There are two groups kept apart from base weight. Consumables are the food, water and fuel carried for the trip. They fall as the trip goes on. Worn items are the clothing on the body and the small objects in pockets, which the walker carries but does not load onto the pack.
Because consumables fall during a trip, the pack is heaviest at the start. Base weight does not change over the trip, which is why it is kept as a separate figure for comparing gear.
A worked ledger
The table is the ledger for one walker. Each category is entered in grams, and the last column shows how the model treats it.
| Category | Grams | Counted in |
|---|---|---|
| Shelter | 900 | Base weight |
| Sleep | 1,400 | Base weight |
| Pack | 1,100 | Base weight |
| Kitchen | 350 | Base weight |
| Water containers and treatment | 200 | Base weight |
| Clothing carried, not worn | 800 | Base weight |
| Electronics | 300 | Base weight |
| Essentials | 450 | Base weight |
| Other | 200 | Base weight |
| Food | 2,400 | Consumables |
| Water, 2 L | 2,000 | Consumables |
| Fuel | 230 | Consumables |
| Worn clothing and pocket items | 1,200 | Worn |
Worked example: one walker of 75 kg
Sum the nine base categories, then add the consumables and the worn items in turn.
base weight = 900 + 1,400 + 1,100 + 350 + 200 + 800 + 300 + 450 + 200 = 5,700 g consumables = 2,400 + 2,000 + 230 = 4,630 g (2 L of water at 1 L = 1 kg) total pack weight = 5,700 + 4,630 = 10,330 g = 10.33 kg skin-out weight = 10,330 + 1,200 = 11,530 g = 11.53 kg pack share = 10.33 ÷ 75 × 100 = 13.8% of body mass
Weighing gear for the ledger
Weigh each item separately, with the bag or case it normally lives in, because that is what gets carried. Write the grams next to the item and add them to its category. A kitchen scale in grams is enough for this, and the entries are easier to check when each one is weighed on its own. Keep every entry in grams, so that the sums in the ledger never mix grams and ounces.
Items with removable parts need care. A stove with its windscreen, or a shelter with its stakes, can be weighed as a whole and as parts. Record both, so that a trip without one part can still be totalled correctly. Empty the water containers before weighing them, so that the water is counted under consumables only.
Recheck the ledger after each trip. Items that were carried and not used are easy to spot in the list, though the ledger does not decide which items to keep. That decision depends on the route, the weather and the people walking it.
Where the weight comes from
Start with the largest categories, because a small change in a small category barely moves the total. Removing 100 g from the 200 g other category changes base weight by 100 ÷ 5,700 × 100 = 1.8%. Removing 500 g from the sleep system, at 1,400 g, changes it by 500 ÷ 5,700 × 100 = 8.8%. The sleep figure is the bigger lever on this ledger, though the choice depends on warmth and comfort as well as weight.
Water is the consumable most tied to the route, because the litres carried depend on where the sources are. Each litre carried is 1 kg, so the 2 L in the example is 2,000 g of the 10,330 g total, or 19.4%. Carrying one litre less removes 1,000 g from the total, and it also changes where water can be found on the route, which the ledger does not model.
Thresholds and what they mean
Many hikers sort packs by base weight. The ledger labels a base weight under 4.5 kg as ultralight by common convention, and 4.5 to 9 kg as lightweight by common convention. The 4.5 kg figure is about 10 lb and the 9 kg figure about 20 lb. These labels are community conventions, not standards, and no governing body sets them. The walker in the worked example, with 5.70 kg of base weight, falls in the lightweight band.
Some hikers also quote the pack as a percentage of body weight. Such rules of thumb are conventions too. The 13.8% share in the example is arithmetic, and it says nothing about whether a load suits a given walker.
Body weight and the energy cost of the pack
Pack weight also drives the energy cost of walking, and the Pandolf equation guide explains how the load enters the calculation. The energy tool accepts loads in 0.5 kg steps, so the 10.33 kg total in the example is entered as 10.5 kg for a 75 kg walker: Loaded miles with 10.5 kg.
What the ledger does not settle
The ledger counts essentials such as first aid, navigation, repair and light, so they are not left out to lower the total. What to carry is a separate question, covered in the ten essentials. A shelter’s weight belongs in the sleep and shelter categories, and what size tarp to choose covers how size affects the fabric and coverage you need. Water treatment counts under water containers and treatment, and filter or purifier sets out what each option does and does not treat.
Common questions
Is worn clothing part of base weight?
No. Worn clothing and items in pockets are excluded from base weight. They count in skin-out weight, which is pack weight plus worn weight. In the worked ledger, 10,330 g plus 1,200 g gives 11,530 g.
Does a full water bottle count as base weight?
No. Water is a consumable, so a full bottle counts under consumables at 1 kg per litre. The empty bottle, filter or treatment kit counts in base weight, under water containers and treatment.
Is there an official ultralight weight?
No. Labelling a base weight under 4.5 kg as ultralight, and 4.5 to 9 kg as lightweight, is a common convention. No standard sets those figures, so compare packs using the same ledger rules for each.
Sources
Published 2 November 2026. Reviewed 2 November 2026. Sources support the figures quoted; they do not endorse Trailwright. Report a correction through the owner’s contact page.