Base weight, explained properly, and what to cut first

Base weight is everything in and on your pack except food, water and fuel. It is the number that does not change between the trailhead and the last night, which is exactly why it is the number worth optimising. Consumables are set by the trip; base weight is set by your decisions, once, and you carry that decision every day.

What base weight is, and what it is not#

Four weights get quoted, and they are not interchangeable.

Two rules settle almost every argument about what counts. First, worn items are not base weight, carried items are, so a jacket in the pack counts and the same jacket on your body does not. Second, the pack counts. Excluding it is the single most common way an unrealistic figure gets published.

Common convention splits base weight into three bands: above about 9 kg is traditional, 4.5 to 9 kg is lightweight, and under 4.5 kg is called ultralight. These are informal conventions, not standards, and nobody issues them. They are useful only as shorthand.

The consumables that sit on top#

Consumables are calculated, not guessed, and they follow directly from physics and physiology.

Food. Sustained walking with a load puts most people between 3,000 and 4,500 kcal per day. Dry backpacking food averages roughly 4.5 to 5 kcal per gram. Divide: 3,500 kcal at 4.5 kcal per gram is 778 g. That is where the familiar 600 to 900 g per person per day comes from, and it is why food selected for calorie density matters more than food selected for weight.

Water. Fresh water has a density very close to 1 kg per litre, so the maths needs no lookup. Two litres is 2 kg, and it is often the heaviest single item in the pack. Carrying water is a routing decision rather than a gear decision: if sources are 8 km apart, carry for 8 km, not for the day.

Fuel. Sized from the number of hot meals and the water volume boiled, which our stove fuel guide works through. Canisters add their own tare, typically 100 to 150 g of steel you carry full and carry empty.

Worked example, one person, three days, two litres carried:

• Food: 3 days times 750 g, which is 2.25 kg
• Water: 2 litres times 1 kg, which is 2.0 kg
• Fuel: 1 small canister, gas plus tare, roughly 0.3 kg

Consumables total 4.55 kg. That number is the reason a 7 kg base weight is an 11.5 kg pack on day one and a 7.5 kg pack on the last afternoon.

How much load your body tolerates#

Load as a fraction of body weight is the constraint that decides everything else. The published thresholds cluster tightly:

Run this backwards and it becomes a budget. A 70 kg walker aiming for the 20 percent band has 14.0 kg of total pack weight. Subtract the 4.55 kg of consumables above and 9.45 kg remains for base weight. That is the entire specification for the kit, derived in two subtractions, and it is what our base weight calculator does with your own numbers.

Note what this implies for smaller walkers. A 55 kg person at 20 percent has 11.0 kg total, and the same 4.55 kg of consumables leaves 6.45 kg of base weight. The consumables do not scale down much, because a day of walking needs a day of food. Lighter people are pushed toward lighter kit by arithmetic, not by preference.

The big three, and why they hold 60 percent#

Pack, shelter and sleep system are called the big three because they dominate base weight in every generation of kit, from canvas to laminates. The proportion barely moves.

Worked for a conventional 8 kg base weight: pack 1.8 kg, shelter 1.7 kg, sleeping bag and pad together 1.5 kg. That is 5.0 kg out of 8.0, or 62.5 percent. Now halve all three to a light kit: pack 0.9, shelter 0.8, sleep system 0.8, which is 2.5 kg. If the rest of the kit (cook set, clothing, first aid, electronics) stayed at 3.0 kg, base weight is 5.5 kg and the big three are 45 percent of it.

That second calculation is the useful one. The big three are where the first several kilograms live, but once they are light, they stop being the problem, and the remaining kit becomes the majority. Kits that stall around 5 to 6 kg have almost always optimised three items and left twenty others alone. If the sleep system is the target, quilts against sleeping bags sets out what the missing back and hood actually cost.

The order of operations for cutting#

Weight reduction has an efficiency ranking, and almost nobody works it in the right order. Sorted by grams removed for the effort and cost involved:

Ranks 1 to 5 cost nothing and routinely total 1.2 to 4.5 kg on a kit that has never been audited. They are also reversible: if you cut something and miss it, put it back. Ranks 6 to 8 cost real money and are irreversible in practice, which is why they belong after the free work, not before it.

Why the pack is chosen last#

A pack is not an independent purchase, it is a response to a load. Frameless packs are typically 400 to 700 g against 1,500 to 2,500 g for a framed pack, so the saving is real, but a frameless pack has no structure to transfer weight to your hips. It works up to roughly 9 kg of total pack weight, and above that the load hangs on your shoulders because there is nothing else holding it. The fit article explains why that fails.

So the sequence is forced:

1. Fix base weight through ranks 1 to 5, free.
2. Replace shelter and sleep system if the numbers justify it.
3. Add the consumables for your longest planned carry.
4. Read the total. That number chooses the pack: frameless under about 9 kg, a light framed pack from 9 to 14 kg, a full suspension pack above that.
5. Size the volume to the compressed kit, using how many litres you need.

Buying the pack first means guessing at step 4, and the guess is almost always too large. The volume then gets filled, and the base weight you were reducing goes back up.

Weigh your kit yourself#

You cannot manage a number you have never measured, and manufacturer weights are frequently for a different size or exclude the lid, the straps or the frame.

1. Use a kitchen scale to 1 g for items under 3 kg, and a bathroom scale by difference for anything heavier: weigh yourself, weigh yourself holding the item, subtract.
2. Weigh every item individually, including stuff sacks, straps and the pack itself. Stuff sacks alone commonly total 100 to 200 g.
3. List them in a spreadsheet in grams, with a column for category and a column for worn or carried.
4. Sort descending. The top ten lines usually account for 70 to 80 percent of base weight. Everything below line thirty is noise, and hunting grams there is a distraction.
5. Mark every item you did not use on the last trip. Those marks are rank 1 in the table above.
6. Re-weigh after the trip, not before. Post-trip is when you remember what stayed in the pack.

The spreadsheet is the deliverable. It converts opinions about gear into a sorted list, and the sorted list makes the next decision obvious.

Common mistakes#

Quoting base weight without the pack. It flatters the number by 500 to 2,500 g and makes comparison meaningless.

Moving items to pockets to lower the figure. Skin-out weight is unchanged. Your legs do not know which container the mass is in.

Cutting the insulation to hit a target. The number is not the goal, the trip is. A 4 kg base weight that gives you a sleepless night at 2 degrees C is worse than a 5.5 kg one that does not.

Optimising the small items first. Replacing a 90 g spoon with a 12 g spoon saves 78 g. Leaving one unused item behind often saves ten times that, for nothing.

Ignoring worn clothing. Boots, trousers and a jacket can total 2 to 3 kg. They are not base weight, but they are on you all day, and the layering system is worth auditing on the same spreadsheet.

Carrying full water past streams. The most common single kilogram of avoidable weight, and the easiest to remove.

Assuming a lighter kit packs itself. A light load in a large pack still rides badly. Load placement matters more, not less, as the pack gets less structured.

Frequently asked questions#

What exactly counts as base weight?#

Everything in or attached to your pack except food, water and fuel. That includes the pack, shelter, sleeping bag and pad, cook kit, spare clothing, first aid, repair kit, electronics and every stuff sack. Clothing you are wearing and poles in your hands do not count, though they still have to be carried by your body, which is what skin-out weight captures.

What is a good base weight for backpacking?#

By common convention, under 9 kg is lightweight and under 4.5 kg is ultralight, but the honest answer depends on your body weight and trip. Work it backwards: take 20 percent of your body weight as a total pack target, subtract your consumables for the longest carry, and the remainder is your base weight budget. For most three season trips that lands between 6 and 9 kg.

How much does backpacking food weigh per day?#

Between 600 and 900 g per person per day for dry food. The arithmetic: sustained walking with a load costs roughly 3,000 to 4,500 kcal a day, and dry trail food averages 4.5 to 5 kcal per gram, so 3,500 kcal is about 780 g. Choosing food by calories per gram, rather than by weight alone, is what keeps this number down.

Should I buy a lighter pack first or last?#

Last. A pack has to match the load it carries: a frameless pack saves around 1 kg but only transfers weight properly up to about 9 kg of total pack weight. Reduce the kit, add the consumables, read the total, then buy the pack that suits that number. Buying the pack first commits you to a load before you know what it is.

Is ultralight backpacking safe?#

The technique is safe, the target is not. Reducing weight through better selection and fewer duplicates carries no risk. Reducing weight by dropping insulation, shell layers, navigation, first aid, water treatment or emergency communication does. If a kit hits a low number by removing safety margin rather than redundancy, it has not been optimised, it has been gambled.

Does the pack itself count towards base weight?#

Yes, always. It is the item most often quietly excluded, and it is one of the three heaviest things in the system. Any base weight figure quoted without the pack should be increased by 500 to 2,500 g before you compare it with anything.

How do I actually weigh my gear at home?#

A kitchen scale accurate to 1 g handles anything up to about 3 kg. For heavier items, stand on a bathroom scale, note the reading, then hold the item and note the second reading; the difference is the item weight. Record everything in grams in a spreadsheet and sort descending, because the top ten items decide the outcome.

What is skin-out weight and why does it matter?#

Skin-out weight is total pack weight plus everything worn and carried in the hands: clothing, footwear, watch, poles. It matters because base weight can be reduced simply by wearing more, which changes nothing physiological. When comparing two kits honestly, compare skin-out weight, or at least state which convention you used.