The Complete Guide to the Standard Backpack Size and Choosing One for Your Trip

Ryan Smith
Jun 29, 2018 · 16 min read

Choosing the right backpack for a trip can feel like an unnecessary stress, often resulting in a genuinely terrible choice or something that suits, but costs the Earth.

As stressful as it seems, however, it is vitally important that you end up choosing the right pack for your upcoming adventures the first time around, as the stress of having to replace one later one, which could be equally bad is far worse than doing it once and doing it right.

In this guide we’ll outline what is a standard backpack size, if there is such a thing, and how to go about choosing the right luggage for you.

(If you are a visual-learner, then scroll to the infographic at the end of this article)

Questions answered will include:

  • What is a standard backpack size?
  • Reporting on the differences for carry-on backpacks and full rucksacks
  • How to choose the best backpack for your trip and what you should be looking for in your luggage
  • Which size backpack you should be looking to take with you on a particular trip
  • How to test out backpacks to make sure they’re right for your body
  • And also how to fit them properly once you own them.

Before we start, the ultimate tip is to give yourself plenty of time to find the right pack. If you’re still six months away from your trip and it seems a long way away, the very least you should be doing is researching to find your backpack.

Without a doubt it’s the most important item you will take with you and the most difficult, by and large, to replace on the road.

What Is A Standard Backpack Size?

With the majority of packs falling between the seemingly endless range of 15 to 85 litres. This range alone is one of the main reasons why so many people can end up making the wrong choice when choosing a pack for their adventures.

This occurs particularly when first taking a trip of a certain type or duration. Someone may have been on a weekend trip to Rome and taken a 20 litre daypack, with the results being absolutely perfect. They apply same logic to a fortnight trip to the same city and find out very quickly that they needed more space than they have.

This can also be reversed, where a person may travel for 6 months with a larger backpack, perfectly, then realize that for their one month trip they are left with so much space in their rucksack that it’s uncomfortable to carry and the contents just unravel and move around.

The same principle can apply to different types of trip; a traveler may venture on a year-long continental trip, taking a 55 litre rucksack, working a charm the entire journey. They then may try and use the same rucksack for a week’s camping and find they don’t have anywhere near enough room for all of their belongings, despite going for far less time than they did in their original trip.

On top of litre capacity, a backpack’s big defining point is its ability to externally carry items.

Lots of sensibly arranged attachment details may be the difference between taking what you need and having to leave behind potentially useful equipment.

Do you need a sleeping back and mosquito net? Some packing cubes? Or bulky hiking boots? Chances are that they would slot nicely on the side of some backpacks, whilst with others you’d have to try and jam them in the main compartments.

Questioning seriously the purpose of your trip before deciding on what type of rucksack you will need is one of the most important aspects of successful backpack purchasing.

What Is The Difference Between Carry-on Backpacks, Daypacks And Multi-day Rucksacks?

Carry-on Backpacks

Different airlines decide what the dimensions for their cabin luggage are, so it’s always important to check company guidelines before you buy a backpack.

But for the majority of cases, the allowance is up to 45 linear inches, or 22 inches long, 14 inches wide and 9 inches deep.

Many manufacturers are aware of these guidelines and have designed packs which perfectly replicate these dimensions.

The benefits of carry-on backpack is that you won’t be charged for hold luggage, and this can also speed up your check-in before a flight.

Cons with carry-on backpacks are that they are generally small, meaning you are more restricted when packing for longer trips, and you have to be very specific on what you pack, as certain items are forbidden from the cabin.

Read More : The Search for the Best Business Backpack That Suits You

Multi-day Rucksacks

Multi-day rucksacks are measured by capacity in litres from 50 to 80, and for most major manufacturers the standardized method is to accumulate the volume of closed storage, which usually includes the main compartment, pockets and hip belt storage.

Other manufacturers may base their capacities slightly differently, which can cause a little confusion, but this is the most common method.

Positives of multi-day backpacks include their superior carrying capacity, number of handy pockets and pouches and space for larger attachments, such as a tent, sleeping bag and sleeping mat.

Negative features of a multi-day are that they can cost money to check-in to flights, where check-in baggage isn’t included, they can be heavy when full and it can be tricky to find a pack which fits perfectly.


The main purpose of a daypack is as the name suggests, to take out on day treks and trips, to carry only the most essential items, such as water, food and spare clothing.

Generally they are between 10 and 30 litres, and can either be compacted to fit inside a larger backpack or can also come detachable, if the manufacturer has included one in their design of a multi-day pack.

Benefits of having a daypack as a companion to a multi-day is largely for comfort and convenience. Rather than taking your entire trip’s worth of items in a full rucksack for a day’s hike, you can separate out only the items you need, and leave the majority of your luggage back at your campsite or accommodation.

There are few cons to taking a daypack along on your travels, other than that they can take up unwanted space when not in use.

What Size Backpack Should You Choose For Your Trip?

Generally you need a few more items of clothing, unless you don’t give too much weight towards personal hygiene, for longer journeys, and you may need more items if you are taking a trip which includes certain activities.

Are you undertaking two weeks of city traveling, 4 nights of camping and wilderness trekking? Or is this the worldwide trip of a lifetime, seeing an amalgamation of all of possible tundra and terrain that the globe can possibly throw at you?

They all require different preparation and a different sized backpack to one another. Let’s look at some examples.

Camping Trips

For camping trips or overnight trekking expeditions with camping included you will need a multi-day pack, largely to carry the extra equipment and food you will require.

Tents, sleeping bags and cooking equipment will usually attach nicely to the outside of a backpack, depending on the model you choose.

Whether you take a daypack along on either of these types of trip depends on whether you will return to the same campsite night after night or if you need to take all of your belongings with you to a new campsite each night.

If it is the latter then a daypack would be largely redundant.

Read More: Five Of The Best Sling Backpacks For Day Treks And Hikes

Month-long Expedition

For expeditions up to a month where accommodation, cooking facilities and food are provided or available to purchase regularly at sites or en route, a carry-on or smaller capacity multi-day rucksack should suffice.

The reason for not needing a larger backpack is that without sleeping and cooking equipment you are unlikely to have too many bulky items with you, with the majority of your pack being taken up by clothing which can usually be well compressed.

Two-month Travel

It is also more convenient for travels that include flights, as only taking a carry-on pack will usually save you money on check-in fees, and you don’t have to wait around for your backpack at baggage claim.

A Real Adventure

The main reason for this is that you will most likely be experiencing a number of different climates and terrains and may need more equipment than if you were simply traveling through the same sorts of environments as is typical of shorter trips.

This table provides some guidelines on specific backpack capacity based on trip duration and season

General capacity guidelines depending on duration & season from Sierra Trading Post.

How To Choose The Best Backpack For You?

To choose the right backpack for you there are a number of criteria you should be taking into consideration.

It is not as simple as just going to a store or clicking online to find the right pack, although both can be a part of the process.

Being the most important aspect of your travels it is important you take the time, try out a few different styles and types, and really think before you make certain your choice.

To first get a shortlist together, you need to ask yourself what features you’d prefer in your backpack, and also what your budget realistically is.

Backpacks come in a number of different forms and levels of quality. Checking out some reviews from trustworthy websites is a good start to deciding what types of features you think would suit your trip.

Another method for getting a good idea of what features you might need for your trip is to go to some local outdoor adventure stores and speak to the staff, outline your trip itinerary and the sorts of activities you’re planning on doing, and they should be able to recommend backpack features that you should be looking out for.

Questions you should be looking to have answers for are:

  • Do I need external attachments?
  • What zip design is most convenient for me, from the top, or around the body?
  • Is it made from good quality materials that will last for the duration of my trip and longer?
  • Are the straps fully adjustable?
  • Are there enough compartments and side pockets?
  • Is it a trustworthy brand with a strong warranty?

From this you should be able to come up with a budget to match what you can realistically afford in a backpack.

Creating Your Shortlist

The next stage is to shortlist a number of them for testing, as even if they seem to have everything you desire, they still might not fit, and it’s best to have a number of different options to fall back on in.

It’s better to have too many options to choose between than not enough.

Select up to ten backpacks to test out in your shortlist, once you’ve selected them, you can then proceed to testing and you’re a step closer to owning your perfect backpack.

How To Test Out A Backpack

The best way to test them out is to go out to your local outdoor adventure shops and physically test out the packs.

If your local shops don’t have them, the next best thing to do is to buy them online, test them when you receive them.

And if they don’t fit right or something is wrong with them, return them to the seller as new (many countries have protection for online buying and you are well within your rights to return products you’re not satisfied with, no questions asked).

This is also why we suggest giving yourself as much time as possible to buy a backpack, as, unless you have enough money to buy ten backpacks before returning them, it could be a time consuming process waiting for your money to return to then buy a new one.

Firstly, comfort and support are what you should be seeking in your chosen rucksack. You are likely to spend a long time carrying this around, so the more comfortable it is, the better for you in the long run.

You also need to take into account how much weight you’re likely to be carrying in the bag, would it still be comfortable and supportive with anything from 5kg to 20kg of equipment inside?

Its weight bearing goes above and beyond comfort, too. Are the materials that the backpack is made of and the strength of stitching of sufficient quality? Will they be able to hold 20kg themselves without falling apart?

Finally, make sure the backpack is in perfect condition, even packs that have been in storage, or haven’t been sufficiently quality controlled can have defects that might be devastating later on in your trip.

Here’s the checklist for quality control

  • All seams should be perfectly stitched, with pressure areas particularly durable.
  • No holes or cuts should be found anywhere other than where obviously intentional.
  • Zips, pull ties and other facets of the bag which open and close should work perfectly as designed.
  • Straps and other attachment apparatus should clip together and function as intended.

How To Fit A Backpack To Yourself?

Body measurements

To avoid potential issues, it’s advised that you follow the right fitting instructions for your body type and your backpack type.

  1. Measure Your Torso Length
From Rei

For a properly fitted backpack, the most important measurement to consider is your torso length.

  • To measure your torso length, first find the 7th cervical (C7) vertebra (the bone you can feel at the top of your back between your shoulders, when you tilt your head forwards).
  • Then run your hands down the side of your torso, with your index fingers facing forwards and your thumbs facing towards each other along your back, until you reach the top of your hip bones.
  • Then run your thumbs across your back until they both reach your lumbar. From this point, up to your C7 is your torso measurement
  • Stand up straight and get someone to measure the distance between your C7 and your lumbar for you.
  • Record the measurement and there you have it, your torso measurement.

2. Measure Your Hip Size

From Rei

It’s also important to measure your hip size when trying to fit a backpack.

Although, usually, if your torso measurement is correct, a backpack which matches should also match your hip measurements, it’s still worth completing this measurement to make certain.

  • To do this, use your tape measure and wrap it around the top of your hips, which you found in the torso measurement.
  • Take it all the way around your body and record the measurement. It’s worth noting that this shouldn’t be confused with your waist size for pants or trousers, as this line is slightly higher than the trouser line, so don’t just use your usual clothing measurements

Pack adjustments

The main aim of fitting a backpack is to ensure that the majority of the weight bearing is done by your hips, not your back or shoulders.

The reason for this is that your legs are home to the strongest muscles in your body and can carry much more of a strain than other areas

On the flip side, your spine is one of the most delicate, and should bear as little weight as possible.

Most backpacks, particularly multi-days, come with a similar style of adjustment, where you can remove the main shoulder straps from a core in the centre of the pack, and simply move it up or down depending on your torso length measurement.

From Ellis-Brigham

Make sure the base of the hipbelt and the top of the shoulder strap are the distance away from each other that you previously measured.

There are four main adjustments you will need to make:

  • Hipbelt
  • Shoulder straps
  • Load-Lifter straps
  • Sternum straps


Before you begin, load up your backpack with the equivalent weight, or as close to, as what you’re likely to be taking with you, as well as a friend or mirror, then adjustments can begin in two different stages.

  1. Hipbelt
From Ellis-Brigham

Firstly, the shoulder straps and hipbelt.

  • Put your backpack on and tighten the hipbelt until it tightly hugs the top of your hip bones.
  • If it seems like it’s a little high, loosen the shoulder straps, if it sits a little low, tighten the shoulder straps, this will alter the position of the hip belt.
  • Clip the hipbelt buckle together, and tighten. The belt should sit comfortably tight, not too tight so that it pinches or hurts, and not too loose.
  • Now double check that the padded hipbelt sits above your hips, if not, tighten or loosen the shoulder straps again until it does.

2. Shoulder Straps

From yuankuei

Now, move onto the shoulder straps. They should again fit snuggly around your shoulders.

If they feel loose, tighten the straps by pulling the cords hanging from each, if they feel tight, pull the buckle of each until they fit just right.

As mentioned, your shoulders should not be carrying much of the weight at all, but the strap should still be tight enough as to relieve the strain on your back.

For the perfect fit, the anchor points should be one to two inches below the height of your shoulders.

3. Load lifters

From StackExchange

Next up for adjustment are load-lifters. These are straps which connect to the shoulder harness and an anchor point near the top of the back panel.

When properly tense, they should sit at a 45 degree angle from your shoulder to the anchor point at the top of your backpack.

It’s important not too over tense these straps, as comfortable as it may feel, it will cause undue discomfort later on in your trip.

4. Sternum Strap

From BoGear

Last on the checklist is the sternum strap. This is the strap that sits between your shoulder straps and connects across your chest, or sternum.

The perfect height for this should be roughly one inch below your collarbones. The width of your sternum strap should be enough so that it is snug, but not too much so that your arms can’t move to their full capabilities.

On The Move

Making sure you’re familiar with your packs adjustment points before you set off is vitally important.

Secondly, memorize your ideal fit when you’re at home, what it looks like, how it feels, as when you’re on the road this will make your overall experience with your pack much better.

When you start to feel aches or pains from your pack, it’s time to adjust the fit. Trial and error will help you find the sweet spot each time, but don’t just accept discomfort as a standard of hiking or traveling.

It is also important to make sure your posture is as good as possible throughout your travels. If your body position is off, your backpack will be too, which will increase the strain on sensitive parts of the body.


Sum it Up

To quickly recap; you should take your time when choosing, decide on the length and type of your trip which helps you decide the size of backpack you will need, decide on the features you need in a backpack, shortlist a number of potential packs, and then use the above fitting guide to decide on if it really suits you properly.

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Originally published at

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Collection of posts from Mr.Abroad

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