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Review: Casio F-91W

Would you believe me if I told you that one of the most legendary watches in the world, crammed with features and complications, could be bought for less than $20? Well, it can, and it’s this, the Casio F91-W. But why is it such a legend?


Cigarettes. Today a health concern, but in 1946, they were the coolest thing since Percy the polar bear put an ice pole in a pile of ice. Without them, there would be no Casio. Let me explain. Apprentice lathe operator Tadao Kashio had just established his own business machining small, complex parts as a subcontractor.

But there’s no glory in subcontracting, so while he machined parts, his three younger brothers scratched their heads for ideas, things Tadao could make that would put the Kashio name on the map. The answer? A small finger ring with a conical cigarette holder mounted on top that allowed hands free smoking right down to the tip.

The idea was a runaway success with the many busy Japanese office workers who had no time for a cigarette break. It was the profits from this idea that went on to fund Kashio’s next project: the electric calculator. Yes, the bedrock of every student’s education, the Casio calculator, was the genesis of the Casio electronics empire—although this one definitely wouldn’t fit in a pencil case.

The world’s first all-electronic calculator, the 14-A went on sale in June of 1957, the product of over three years of problem-solving. At every step, the solution was to remove archaic mechanical technology and replace it with electronic relays, which sped up both the input and calculation processes. For example, on a gear-driven mechanical calculator, each number in the line had its own column of buttons from 0 to 9. The 14-A gave us just one selection of buttons for every number in the line, just as we have on calculators today.

Naturally, the business worked its way through every mechanical office item still in service and rewrote the rulebook to make it electronic. Typewriters, scientific calculators, calculators with memory, and finally, in 1968, the 152, an electronic calculator with an integrated circuit. Over time, these devices shrank to become portable and personal, until in 1974, Casio released its most portable electronic device yet: the Casiotron.

The Casiotron QW02 was not just Casio’s first watch, it also established the blueprint for how pretty much every Casio watch functions today. As well as the time, regulated by a quartz crystal and integrated circuit, the Casiotron also had an automatic calendar that didn’t need changing at the end of the month. Aside from costly perpetual calendar wristwatches, this was the first time the average consumer could own such a device.

The Casiotron was updated two years later to the X-1, which added a world timer and the all-important stopwatch, and from there it was a process of refinement, making it smaller, cheaper, more battery efficient. Yes, there were other technological developments, such as the 1980 C-80 calculator watch, the 1983 G-Shock DW 5000C and the 1985 FS-10 ultra-thin, but what we’re interested in here is the watch for everyone, which started with the 1980 F-5.

With a resin case and strap, no water resistance and an incredibly basic display, the F-5 set the ball rolling for the nine years of tinkering that would eventually lead to the legendary F-91W. There were some 30 models made in those nine years, each with many variants, and many more have come since. So what makes the F-91W so special?


Released in 1989, the F-91W was barely distinguishable from many of its other siblings, yet it has risen to become a watch sold by the millions every single year. It was the first watch designed by Casio’s chief designer Ryusuke Moriai and packs a whole bunch of features into its tiny resin case, including a 1/100th of a second chronograph with split seconds, an hourly alert, daily alarm function, annual calendar and backlight.

It was the go-to watch for children and armed forces alike, that sweet spot of budget, toughness and functionality basically unmatched anywhere else. Even the water resistance, rated at 30m, which is categorised as splashproof, has been routinely proven to be much greater. Basically, it can withstand almost anything, and is cheap enough to be easily replaced when it can’t.

Where the F-91Ws unexpected fame—or rather, infamy—came from, is in its ability to be replaced easily when it does get destroyed. This is a watch that earned the nickname, the “Taliban Special,” because its accuracy and low price made it the ideal candidate as a timer in improvised explosive devices. Officials at Guantanamo Bay were instructed to treat ownership of the F-91W as an identifier for terrorism—even though many of those officials were also owners of the watch.

It's said during the peak of the war on terror that a person wearing an F-91W in an airport had an increased likelihood of being searched, and that bulk purchases of F-91Ws were monitored by federal securities. The reality is that the F-91W was just the best, cheapest watch on sale, and its application was universal. Targeting people by the wearing of the most sold watch in the entire world is the very definition of finding a needle in a haystack.

The F-91W has continued to find success for the same reason it first found it: it’s cheap, it’s functional, it’s ubiquitous. The recent 80s fashion trend has also seen non-watch wearers embracing its no-nonsense looks, with younger generations even deliberately choosing it as an anti-luxury icon in protest of the ever-growing divide in wealth. The bizarre thing is, the F-91W looks just as at home next to a Patek Philippe grand complication as it does on the bedside table of an eight-year-old.

Not to mention that this black version is far from the only variant. There are as many colours available as you can think of, including “jelly” transparent models. And with it being so cheap, it means having a different colour for every day of the week is entirely possible.

So, what are the cons of owning an F-91W? Well, it’s cheap for a reason. This isn’t a luxury watch. The resin strap can get a bit sweaty and, although the battery is said to last seven years, it still needs changing. The calendar doesn’t sort leap years either so that needs changing manually in February. The side-mounted backlight is also about as bright as Kim Kardashian.

To be honest, the very similarly priced W-86 is actually a better watch. But it’s not always about better. The F-91W is the watch that evokes childhood memories of trying to stop the chronograph on exactly one second, the one that got the guards of Guantanamo Bay quaking in their boots, a watch that, before the Apple Watch, was the most popular in the entire world. I mean, at that price, you can just have both.

What do you think of the F-91W? Is it an icon in your eyes? Is there a watch you think of that better deserves the top spot?