Casio F-91W Review – 10 Years Later

The Casio F-91W, the tried and true watch that might just get you sent to Guantanamo.

I’m now on my third Casio F-91W. After being tired of finding my phone stuck in my jean pockets when all I need is the time I found myself searching for a watch.

What I found was a ridiculous number of sometimes insanely priced watches.

All I wanted:

  • A simple watch
  • Preferably digital
  • An alarm
  • The date, and
  • A couple meters of water resistance for the rain or odd river crossing in the back country.

After a few long hours searching the depths of amazon and eBay I came across something I thought had to be a miss-price, the Casio F-91W. What is it?

Its an astoundingly simple watch. So ubiquitous it goes unseen by many. It even has such a following it has its own wikipedia page, which is worth a read by the way.

The Casio F-91W has become so ubiquitous and available that a certain terrorist group started using it to the extent the TSA might give you a second look for wearing one.

The features of the F-91W are spartan yes, but so well designed and thoughtful I’d like to cover them in some depth especially in regards to backpacking but I will cover every day situations too.

The Casio F-91W

Casio F-91W

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  • Ultralight weight (0.7oz, or 20g)
  • Slim design, doesn’t snag on clothes
  • 7 Year battery life
  • Bombproof construction
  • Can handle the shower or a swim
  • Inexpensive


  • Straps weaken and break after 3-5 years (on my third)
  • Scratches are inevitable
  • Not made in the USA
  • Looks a bit retro

The classic Casio alarm

The watch has two alarm modes, a simple hourly beep at the top of the hour, and a customizable daily alarm.

The daily alarm will chime a set of 20 beep-beep’s before realizing you’re in a different room, this prevents the watch’s battery from draining and I find is enough to wake me up.

During heavier sleeps – which tend to happen outdoors when I want to wake up and hit the trail early, I find the alarm isn’t quite enough to wake me every time. I found tying the watch to some cord and dangling it in front of my face from the top of the tarp solved that problem.

The alarm, like the date and time, is relatively simple to work out I believe I only read the manual once.


The stopwatch was a feature I never thought I needed until I had it. I use it most often for timing something in the oven.

Out hiking I find myself using the stopwatch a considerably amount, especially on day hikes where I’m tracking my pace. Working from trail time estimates I’ll estimate my progress to make sure I’ll be home before dark or just to update my walking partners to let them how long we’ve been walking. I don’t know about you but my hiking partners like to chime on how long we’ve been walking I like to be able to tell them its only been 17 minutes.

Is the Casio F-91W Waterproof?

The Casio F-91W is labeled of having water resistance to a depth of 5m.

What does that mean in every day terms?

5 meters of water resistance is enough to wear through the rain, go for a swim, cross a river, wash your hands, or as I do yes, you can even shower with Casio F91W.

The only time I have ever had a problem with water causing damage was while I was on my second F-91W. Where I somehow lost one of the backplate screws, after a few weeks condensation from taking showers built up in behind the screen cover. After realizing the lost screw I dried the watch out for a few days then replaced the screw using one from my first watch – I still had the old one as it worked more or less fine as only the strap was broken! Since then I haven’t had any problems.

Casio F-91W Battery Life

The battery life on this thing is crazy, today we talk about smart watches with battery life numbers in the days and hours. While this watch! This watch’s battery will last you a solid SEVEN YEARS at least.

In all honesty, the straps tend to deteriorate, tear or snap before the battery ever dies however you can find replacement straps online and replacing them is relatively simple with a push pin. If you’re not happy with the standard black strap you can sometimes search around online for different colors and materials (I’m currently rocking a bright green sports style strap on mine.)


If you’re looking for the lightest ultralight backpacking watch, the Casio F-91W is incredibly hard to beat.

At 0.7oz, that’s only 20g, it’s the lightest backpacking watch available and you’ll hardly feel it on your wrist.

Shape and Fit

The shape and fit of the watch is incredibly low profile, it’s not bulky like newer smart watches, or even like older style gshock type watches that tend to bulge and get caught in clothing constantly. Its slim, light, and only does what its supposed to do.


As I’ve just mentioned, the only real problem I’ve had was where the rubber/resin straps deteriorated after a lot of time in adverse conditions like hot showers and lots of sunshine.

Other durability problems I’ve noticed is the front isn’t very scratch resistant, being plastic, a few brushes against a boulder or two will eventually leave a few war wounds. It’s nothing I’ve ever worried about, but it is there if you look closely.

Strength and design wise, other than the straps, the thing is a tank and you could drive over it and not worry, its flat, compact, and robust.

Affordability and Availability

The Casio F-91W is probably one of the cheapest watches you will ever find that delivers the same qualities and features. Its price is so low, simply because after their first run in 1991, and now over three decades of production, they’ve managed to get the cost down as low as feasibly possible.

The watch is available in almost any country of the world, and online shipping is almost always free as it tends to just be shipped in a flat bubble wrap envelope.

The Verdict

The Casio F-91W is an alarming, water resistant, superstar that I don’t ever see leaving my wrist – and even if I replace it in town for something “smart”, I’ll always go back to the Casio for backpacking and hiking for its simple reliability and lightweight effectiveness.

Oh, and by the way, the F-91W is only the most popular of the entire F-series, if you like its features, but don’t like its slightly dated retro look, you might be able to find something a little more grown up, one of my friend uses a stainless steel version where the straps don’t wear out nearly as quickly.

Or if you’re ok spending a little more for an improved light function, I’ve been wanting to trial out the famed F105W-1A which is in all respects the same watch, behaves and looks exactly the same it just comes with a slightly different faceplate and a backlit screen when you hit the light button.

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