One Hundred Million and Counting.
4 min read
The Casio F-91W has been in production since 1989. The design has not changed. Not the case, not the module, not the strap, not the LCD layout. Thirty-seven years of the exact same watch, produced over and over, and it has sold more than 100 million units. No other watch in history comes close.
It was designed by Ryusuke Moriai as his first project at Casio. He went on to create some of the most iconic G-Shocks ever made. But his debut was this: a 21-gram resin rectangle with a module that costs almost nothing to produce, a battery that lasts seven years, and a price tag that makes it disposable.
And yet people keep it. For decades. There is something in this object that refuses to be thrown away.
Through the eyes of a designer
The F-91W is 35.2mm wide, 38.2mm lug to lug, 8.5mm thick. It weighs less than a stack of coins. The case is resin with a stainless steel back. The crystal is acrylic. The strap is 18mm urethane. Every material was chosen for one reason: cost efficiency.
But cost efficiency, when pursued with enough discipline, produces its own kind of beauty. There is no decoration on this watch. No brushed surfaces, no polished edges, no logo placement strategy. The LCD display shows hours, minutes, seconds, day, and date. The three buttons on the side control everything. The backlight is a green LED so dim it has become a meme. Casio never upgraded it. At this point, the weak light is part of the identity.
From a design perspective, the F-91W is what happens when you remove every element that does not serve a function. No curves for style. No textures for perceived quality. No weight for perceived value. What remains is an object that is entirely honest about what it is: a device that tells time, reliably, for almost nothing.
That is harder to design than it sounds. Most products add features to justify their price. The F-91W justifies its existence by having nothing unnecessary.
Who wears it
This is where it gets interesting. Barack Obama wore one. Billionaire Chuck Feeney wore one. Subcomandante Marcos wore one while leading a rebellion in southern Mexico. Fidel Castro wore one. It appears on the wrists of soldiers, students, software engineers, and collectors who own watches that cost a thousand times more.
The F-91W does not signal wealth. It does not signal taste. It does not signal membership in any tribe. It signals something harder to define: a complete indifference to what your watch says about you. And paradoxically, that indifference has become its own form of status. Wearing a $17 watch when you could wear anything is a statement about priorities.
What I honestly think
The F-91W is not a serious horological instrument. It is quartz. It is plastic. The accuracy is plus or minus 30 seconds per month, which is fine but unremarkable. The water resistance is rated at 30 meters but most owners treat it as splash-proof at best. The strap degrades after 18 months of daily wear. The acrylic crystal scratches if you look at it wrong.
None of that matters.
The Casio F-91W is the most democratic object in horology. It does not care who you are, what you earn, or what you think about watches. It tells time. It costs less than a book. It lasts longer than most relationships.
I own one. It sits next to the Axel Elite Silver in my collection. One is an automatic skeleton that got me into horology. The other is a plastic rectangle that has sold 100 million units without changing a single thing about itself since 1989.
Both belong there.
Main Log. Entry 005. Horo Log