Throughout the past year, I think I’ve experienced a considerable shift in my collecting philosophy. What I like and what I’m drawn to has changed throughout the lifetime of this website—I’ve even cooled down on my IWC lust. Whatever it is, I’ve become less concerned with signaling something to others with the watch on my wrist, particularly to the online world and without much concern over price. This has led me to enjoy watches closer to my collecting origin story; a basic Timex, a G-Shock, an older Seiko 5, or the classic Casio F-91W in its varying flavors and colorways. It’s the kind of shift that can revive interest in a hobby, which can get stale over time.
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Case | Dial | Strap | Movement | Final Thoughts
Casio F-91W Specs
| Case Size | 34mm (diameter) x 38mm (lug-to-lug) x 8.5mm (thickness) |
| Water Resistance | 30m |
| Movement | Casio Quartz Module 593 |
| Case Material | Resin |
| Crystal | Resin |
| Lug Width | 18mm |
| Strap | Resin |
| Price | $15 – $20 |
This little black digital watch needs no introduction. The Casio F91 series is both famous and infamous for reasons I won’t get into here—I’ll leave that part to Watches of Espionage. Word on the street is that an estimated three million are produced every year. Prices on these climb sometimes but you can generally score one at around $15 and it’s more accurate than your Rolex. It’s fun, it works, it’s affordable, and I challenge collectors of all means and backgrounds to test drive one of these for a month and see what it can do to their “watch enthusiast” perspective.
Lightweight resin case
Casio refers to the case and crystal on the F-91W as resin in their material construction. So … plastic, a very plastic-ky plastic. It makes for an incredibly lightweight timepiece and together with the resin strap, the whole watch clocked in at 20.5g on my scale. In terms of size it’s about 34mm in diameter, 38mm lug-to-lug, and 8.5mm thick. And if those dimensions sound like something you’d never touch, just know that this is almost universally well-worn by a wide range of consumers—from scrawny Cap Hill hipsters all the way to SOF guys with tree trunk wrists. Try it. You might be surprised.
I think the small dimensions are also helped, visually, by the resin bumpers found on the four corners of the case. They flare out just a tad and make the watch seem a little more substantial on the wrist. They also allow for the three buttons to be actuated with positive confidence, unlike a Timex Expedition I reviewed recently. The caseback is also stainless steel, with basic engravings and four little screws. Casio also mentions that the watch is water resistant but doesn’t specify to what degree consistently across all models. The general consensus is 30m. This has led many to shy away from getting these watches wet. But, take a quick moment to search “F-91W torture test” on YouTube and you’ll quickly find that the watch will stand up to a casual swim just fine.
Charming retro dial
For such a small watch, the LCD display on the F-91W is pretty easy to read and packed with information. The two versions I have here are a little different in their coloring, with blue/red on the Casio F-91W-1YEG and green/orange on the Casio F-91W-3DG. I’ve read that this green/orange model is either some kind of JDM market or international model that can be tougher to find, with a mysterious little “-U-” marking just under the retro “Resist” text. I have no clue what that means and this version wasn’t hard to score on Amazon at all—I find myself wearing this one a little more actually. Both versions have arrows and text at the case corners that clearly mark the function of the corresponding buttons.
And then there’s the LED light. Unlike older Casios, these versions both have a single green LED bulb that lights up the display (or one corner of it, really). It’s not really a full backlight situation. Honestly, it’s not going to win out against something like Indiglo but I wasn’t really expecting it to. It’s more like a party trick … a really boring party trick. But overall, I like the visibility you get on the display while operating any of the available modes.
Basic strap with room for mods
The resin band on the Casio F-91W is as simple as things get. It’s integrated directly into the case and has a soft, comfortable construction to it. The plastic buckle is minimally branded and I’m glad the strap has enough holes to nail a great fit. I never really had a problem with Casio watches when it came to straps and this one fits just fine. But it seems like you can have some real fun popping this strap off and putting the watch on a NATO. Don’t take my word for it—the nearly 4,000 members over at r/F91Ws_on_NATOs seem to be having a blast with that little modification.
The classic quartz module we grew up with
This specific timekeeping module (Module 593) offers functions for a daily alarm, a chronograph/stopwatch, an annual calendar, and an hourly chime. You can also set it to display time in 12 or 24 hour formats. There’s also a fun little Easter egg. Hold down the bottom-right button for a few seconds and you’ll see “CA510” displayed on the entire screen. Can your Apple watch do that? This is apparently an anti-counterfeiting measure by Casio. Because, I guess people make fake F-91Ws.
The quartz movement is estimated to be accurate to +/- 30 seconds per month, but I think that’s extreme and it probably performs a little better than that. It’s all powered by a CR2016 3-volt lithium button cell and I’m guessing these can tick away for years. You won’t really have to worry about battery life too much. All told, I find this module a little easier to navigate and adjust when I compare it to other digital watches. And it’s easy to understand why this might actually end up as a one watch collection for the regular person out there that isn’t obsessing over mechanical watches and collecting all day.
Taking the plunge
This wasn’t really a watch review I ever thought about writing. I feel like everyone that’s into watches must’ve handled one of these at some point. They’re so incredibly ubiquitous across the world—like a classic Bic lighter or Pilot G-2 pen. But getting my thoughts down here has really helped clarify my recent attraction to these watches and if you’re still here, thank you. Welcome to my journey back to basics.
Does this mean I’ll cut out every other sport watch and just have myself a Casio collection? Probably not. But I will be a little more intentional whenever I choose to wear these watches. It’ll make for less of an ironic, gimmicky wrist check. And more of an instance of pure enthusiasm. That’s horology enthusiasm everyone can enjoy. If for some reason you haven’t taken the plunge, please do. These come in more colorways than what you see here, like the F-91WG with the gold trim or F91WM models with fully colored cases. Whichever one you go for, it’s sure to leave a smile on your face.
Co-Founder & Senior Editor
Michael Peñate is an American writer, photographer, and podcaster based in Seattle, Washington. His work typically focuses on the passage of time and the tools we use to connect with that very journey. From aviation to music and travel, his interests span a multitude of disciplines that often intersect with the world of watches – and the obsessive culture behind collecting them.
While not my first watch, this was what I wore as a teacher for years. Most comfy watch by far in the collection and a reminder of what a watch should be. A reliable tool that is fun to wear. Always appreciate the content and more so when it hits close to home!
Nice article Michael! With all the hype out there we forget what got us interested in the beginning, a basic, functional and accurate time piece. I’ll offer up my own Casio EAW-MRW-200H-1BV Men’s MRW200H-1BV Black Resin Dive Watch as an example.
I have it. I love it. It makes me happy. My 4 year old daughter loves it to, and I love that I can let her fiddle with it without worrying about it breaking.
Hello! I really enjoyed this write up and the comments. So, thought I would share my Casio collection with you. I purchased ‘3’ new Casio wrist watches back in 1992 and only had to change the battery once from factory install. these “3” are W74/593 module A162/593 both have Japan M on back and Japan “U” on lower face. Now the other is a A158W/593 Korea DK on back and no “U” or Japan on lower front. Thank’s for letting me post……………Henry
It knows the number days in each month and shows the correct day of the week as it changes date. The only thing it can’t do is recognise February 29th but can any watch?
I’ve been thinking about getting a couple of Casios for a while and this one is at the top of my list. Thanks for such an in-depth review of such a classic, iconic watch.
Great review i am going to buy one tomorrow.
I’m on my third F-91W. The first one lasted about ten years – I broke it while trying to change the strap, but the original battery was still going strong. My second one lasted fifteen years before the battery failed: I couldn’t replace it because it seems that the main body of the watch is now a ‘sealed unit’. Booooo! These are first class devices – they look good and keep excellent time. Only other criticism I’d make is that the standard strap doesn’t last much more than 18 months.
Ive just gone back to these small form Casios after years of wearing smart “watches” and its reignited my love for watches!
Will this remain my daily probably not! Am I currently watching out for deals on a few more various models to add to my rotation hell yes! I could easily have 2 or 3 maybe an A188 on a metal strap!
These little watches are just amazing at what they do no fuss no fluff!