REI Co-op Flash 18 Review

Updated: March 31, 2023

The REI Co-op Flash 18 is a super-lightweight daypack, perfect for anyone who needs something versatile but is on a tight budget. The Flash 18 was the cheapest and lightest pack that we reviewed in our best hiking daypack review, and so we gave it our best lightweight and budget daypack awards.

We found the best use for this pack to be for short hikes from your campsites and for summits, as the lightweight and small design makes for easy climbing. However, because of that compact design, we also found it to be one of the more versatile daypacks that we’ve tested.

At only $40 (at the time of writing this), we’d also say that it’s the best pack for beginners because of that versatility and extremely affordable price point. So look no further if that sounds like something that fits your needs!

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REI Co-op Flash 18

Manufacturer: REI


  • Cheapest ($40) and lightest daypack that we reviewed 
  • Extremely light and very versatile
  • Nice, minimal and compact design


  • Small top-loading opening
  • Lacks any real support or comfort when it’s loaded heavily
  • Not very durable


The most obvious thing to like about the Flash 18 is the compactness of the design. It can be folded up and stuffed into a larger backpack or suitcase, making it a perfect last minute purchase that won’t break the bank for use while on holiday. While we could hardly call it feature-filled, it still offers most of the necessities that you’ll need at that awesome price.

As we mentioned, we found the Flash 18 to be one of the more versatile pack that we’ve tested. That was probably our favourite thing about it, really, as we could use it everywhere we went; from gym, to the office, to the hiking trails, and even to the ski slopes. Coupled with that price tag (we’ll keep repeating this because it’s amazing!), it definitely offers the most bang-for-buck out of any other daypack.

Now, making a lightweight pack like the Flash 18 doesn’t come without its downsides. It fell short on comfortability as soon as you load it with more than 6kgs of gear, as the lightweight shoulder straps start digging into your flesh.

While it wasn’t too bad for very short periods, it was noticeable as soon as you had to carry it for more than half an hour. Also, in order to keep that price tag and weight down (we’d assume), REI’s Co-op brand design team had to forego a lot of extras with the Flash 18, and that, we found, took a big bite out of the overall durability of the pack.

Finally, while it was perfect for tasks that don’t require a lot of gear or much organisation, the Flash 18’s top-loading design didn’t hold up well at all for other tasks.

So while we have stressed the strength of this pack’s versatility, we have to note that it’s only versatile in terms of activities that are short and don’t require constant access to the contents of the pack.

See Other Daypacks

Finding the correct daypack for your needs and budget remains a tricky task and sifting through the troves of reviews can be time consuming and confusing. To make things easier, check out our expert review on the best hiking daypacks here.

REI Co-op Flash Features

Capacity and Weight

At only 18L, the Flash 18 is definitely on the smaller end of the daypack spectrum. With this pack, though, we find this to be more of a feature than a disadvantage as it seems to be with other small packs.

The sole purpose of the Flash 18 is to be a small and lightweight pack to get you around the tightest of hikes or to allow you to move quickly while skiing or mountain biking. So, while it is small, we found the capacity here to be more than enough for its intended purposes.

At this point it’s obvious that this pack also excels in the weight department, at only 284g, it’s easily one of the lightest packs we’ve tested. We’ve already discussed the shortcomings of targeting such a lightweight design, with the feature-list being diminished slightly, but in this case it’s so light that we’d be more than willing to overlook those disadvantages.

Ventilation and Comfortability

This was one of the departments where the Flash 18 suffered for its minimalism. There’s no sign of a frame in the back panel, which means there’s little to no support to help keep the shape of the pack. This makes it easy to pack too much and distort the shape of the pack, rounding the back and making it sit horribly between your shoulders. As we mentioned before, we’d recommend not packing a lot of heavy gear into this pack; your shoulders will not appreciate it if you do.

As for the ventilation, it lacks any form of ventilation foam on the back panel. This doesn’t mean that it’s not breathable, however. Having such a thin layer of padding between your back and the innards of the pack actually provides a good bit of airflow. This is, once again, subject to how fully you load it. The shoulder straps are fairly padded and ventilate well, but dig into your shoulders at the first sign of overloading.


The most obvious thing about the Flash 18 when it comes to functionality is that it only has the one main compartment and one small zippered pocket on the back (that doesn’t really fit much).

No stretch-mesh pockets on the back or sides. That makes it incredibly inconvenient if you need access to water bottles and snacks while on your day activity, especially since it’s a top-loader.

In order to combat this, somewhat, is the fact that the Flash 18 is at least hydration compatible and you could get away with a 3L reservoir; provided you’re willing to give up 3L of capacity for your other gear.

There are a few other useful things to point out, such as the hipbelt and the sternum strap (which don’t provide much in the way of support anyway) being removable; and the sternum strap also doubles as a safety whistle in case of emergency. Lastly, it does also have four loops that give you options for attachments or for extra lashing.

Materials and Design

We’ve pretty much covered everything that we need to in terms of the material and design choices that REI’s Co-op brand made with the Flash 18. Everything was carefully thought out to minimise the cost and the weight.

The last thing to note is that the pack struggled quite a bit when it came down to our durability tests. The ripstop nylon design protected the contents from slight rain, but anything more than that got through pretty quickly. The material did hold up pretty well otherwise, without much damage being done throughout our testing.

About the author 

Mark Whitman

Mark has trekked extensively in Asia, Europe, South America and Africa. He founded Mountain IQ in 2014 with the sole aim to be the best online information portal to some of the most popular mountain destinations around the world. When not writing for Mountain IQ, Mark is out exploring the outdoors with his wife!

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