Pack Weight to Body Weight Calculator
The commonly cited guidance is a loaded pack at about 20 percent of body weight and a base weight at about 10 percent, so a 170 lb hiker targets a 34 lb pack and a 17 lb base weight. Both are rules of thumb, not physiological limits.
Almost every hiker has heard that a pack should be about 20 percent of body weight loaded and about 10 percent as base weight. It is a useful starting point and a poor law. This calculator does the arithmetic, shows how far above or below the figure you are, and then the page explains where the rule comes from and where it breaks down, because a percentage that ignores pack fit, terrain and how long you have been walking is not the whole story.
Applies to both fields below.
Loaded includes food, water and fuel.
Under the commonly cited target.
Bars are drawn against 30 percent of body weight, which is roughly where load carriage guidance stops being casual.
What is the rule, precisely?
Pack weight as a percentage of body weight is your loaded pack divided by your body weight, times 100. The two figures repeated everywhere are 20 percent for a loaded pack and 10 percent for base weight, and the second follows from the first once you account for consumables.
| Body weight | 10% base weight | 20% loaded pack | 25% loaded pack | 30% loaded pack |
|---|---|---|---|---|
| 120 lb | 12 lb | 24 lb | 30 lb | 36 lb |
| 140 lb | 14 lb | 28 lb | 35 lb | 42 lb |
| 160 lb | 16 lb | 32 lb | 40 lb | 48 lb |
| 180 lb | 18 lb | 36 lb | 45 lb | 54 lb |
| 200 lb | 20 lb | 40 lb | 50 lb | 60 lb |
| 220 lb | 22 lb | 44 lb | 55 lb | 66 lb |
Read the 10 percent column against your gear list and the 20 percent column against day one of a trip, when food and water are at their heaviest. Those are different questions with different answers, and conflating them is why the rule confuses people. If you do not know your base weight yet, the base weight calculator takes about two minutes.
Where does the 20 percent figure come from?
Not from a single study anyone can point to. It is generally traced back to military load carriage guidance and general fitness advice, then repeated by retailers and guidebooks until it acquired the authority of a physical constant. What the load carriage literature does show reliably is narrower and more useful: energy cost rises faster than load, so each additional pound costs more than the one before it, and load placement and pack fit change perceived effort substantially at identical weight.
So the percentage is a heuristic that encodes something real without being precise about it. Treat it the way you would treat a target heart rate formula: a reasonable place to start, obviously wrong for some people, and no substitute for how you actually feel at mile fifteen.
Why does the rule punish smaller hikers?
Because gear does not scale with the person carrying it. A shelter, a stove, a water filter, a headlamp, a first aid kit and a repair kit weigh nearly the same whether you weigh 120 lb or 200 lb. Only clothing and the sleep system shrink meaningfully, and not by much.
The consequence is that 10 percent of body weight as base weight is a 20 lb allowance for a 200 lb hiker, which is a normal lightweight kit, and a 12 lb allowance for a 120 lb hiker, which demands genuinely ultralight gear. That is not a discipline problem, it is arithmetic. Smaller hikers usually have to spend more money and accept more deliberate gear choices to reach the same percentage, and it is worth naming that rather than pretending the target is equally easy for everyone. The tier definitions that sit behind all of this are on the base weight tiers chart.
What matters more than the percentage?
Three things, in order.
- Whether your pack suits the load. Frameless and lightly framed packs carry well to roughly 25 to 30 lb and poorly above it, because nothing transfers weight to your hips. A 32 lb load in the right pack feels lighter than a 27 lb load in the wrong one, which is the whole argument in frameless versus framed packs.
- Where the weight sits. Dense items high and close to your spine, light bulky items low and outboard. The same pack weight can feel like two different loads depending on the packing order.
- How many consecutive days you are doing it. One heavy day is a workout. Five heavy days is an injury risk, because the effect accumulates in tendons and feet long before it shows up in your legs.
What to do if you are over the number
Start with consumables, because they are usually the largest and cheapest thing to fix. Four litres of water is 8.8 lb and often two litres more than the terrain requires, and a week of food packed at 100 calories per ounce instead of 120 is roughly 2 lb of avoidable weight. Both are free to change: run them through the food weight calculator before you shop for anything.
Then work down the gear list from the heaviest item rather than the most annoying one. Shelter, sleep system and pack are usually about two thirds of base weight, so that is where a pound actually lives. The ordered method is in how to cut base weight, and if the pack itself is the problem, the ultralight backpack roundup covers what a lighter pack does and does not fix.
What does not get cut to hit a percentage: rain gear, insulation, navigation, water treatment and an emergency communication plan. Going ultralight must not mean going unprepared, and no percentage target is worth arriving at a cold camp without a shell.
Frequently asked questions
What percentage of body weight should a backpack be?
The figure repeated across retailers, guidebooks and outfitters is about 20 percent of body weight for a loaded pack, and about 10 percent for base weight. For a 170 lb hiker that is a 34 lb loaded pack and a 17 lb base weight. Both are rules of thumb rather than physiological limits, and fitness, terrain, pack fit and trip length move the real answer in either direction.
Is the 20 percent rule actually backed by research?
Not in the way people assume. The figure is usually traced back to military load carriage guidance and general fitness advice, then repeated until it sounds like a law. What research on load carriage does show consistently is that energy cost rises faster than load, and that pack fit and load placement change perceived effort substantially at the same weight. Treat 20 percent as a useful starting point, not a threshold.
Should I use base weight or full pack weight for the percentage?
Use both, for different jobs. Base weight against 10 percent tells you whether your gear list is in reasonable shape, because base weight is the part you control by buying and packing. Full pack weight against 20 percent tells you what your body actually has to move on day one, when food and water are at their heaviest. The second number is the one your knees respond to.
Does the percentage rule work for smaller hikers?
It works less well the lighter you are, because gear does not scale down with you. A shelter, a stove, a filter and a headlamp weigh nearly the same for a 120 lb hiker as for a 200 lb one, so the smaller hiker hits 20 percent with a kit the larger hiker would call minimal. Smaller hikers usually have to go genuinely ultralight to land near the target, which is a real cost rather than a failure of discipline.
What happens if I carry more than 20 percent of my body weight?
Usually nothing dramatic, and plenty of people carry 25 to 30 percent regularly. What changes is pace, fatigue and joint load, and the effect compounds over consecutive days rather than showing up on day one. If you are over the figure, the questions worth asking are whether your pack has a frame suited to the load, whether the heavy items sit high and close to your spine, and whether the excess is gear or consumables.
Does a heavier pack need a different backpack?
Yes, and this is where the percentage matters most. Frameless and lightly framed packs carry well up to roughly 25 to 30 lb of total load and become uncomfortable above it, because there is no structure transferring weight to your hips. If your loaded pack is above that, a framed pack will feel lighter at the same weight, which is one of the few genuinely free improvements available.
How we choose: we compare published manufacturer specifications, listed weights, and verified owner reviews across retailers. We do not test gear in person, and every weight quoted here is the manufacturer's figure unless we say otherwise, so weigh your own kit before you trust a total. Going lighter also means carrying less margin, so treat insulation, navigation, water treatment and an emergency plan as fixed costs rather than places to save grams.