Casio F 91W Manual – Favorite Watch Of Millions

In this article I will show you what makes the Casio F91W the favorite of millions of users. A good number of you who are reading this article may be quite familiar with the Casio F91W; you might be using one at the moment, or have used one in the past. It is a very popular and affordable watch, in fact if I am not mistaken, it is the model that Casio has produced the most.


The flat, square, and simple design makes it adaptable to anyone’s wrist and thus, a unisex watch as well as one that suits for all ages. On top of that, digital quartz watches are well known for giving accurate time.

Casio F 91W Manual

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Casio F 91W Manual

Time, Day and Date

The time display has both 12 and 24 hour, and as per your choice, you can switch by pressing the button found on the right side once. The watch also displays seconds, and features the day and date of the month as well.

To set the time and date, press the mode button four times, you will see the second blinks. Press the light button the switch to hour, minute, day and date, and press the button on the right to forward the digits. Then press the mode button again to finalize the settings.


One of its many functions is the very easy to use chronometer;  i have used it extensively while swimming, diving, running and several other activities. However, it cannot record several laps as in other Casio models. To switch to chronograph, you simply have to press the mode button twice and then press the button on the right to start and stop the chronometer. You can reset the chronometer simply by pressing the light button.


It has one alarm which can be set at any desired time, such as to wake up in the morning. You may also set it to beep every hour which is very nice and informative of time during the day but not at night. I prefer to turn off this setting whether for this watch or another.

To set the alarm, press the mode button once and then press the light button to make the alarm time blinks. Press the light button the switch to hour and minute and press the button on the right to forward the time.


It has that small yellow light which gleams from its left when you press the the top-left button.

Long lasting battery

And now, to relate my own experience, I had my Casio F91W when i was in college, and it was the best timepiece i could have at that time. Today, more than ten years later, it is still in my locker and still functioning, though I don’t wear it anymore. The Casio F91W watch actually comes with a battery (CR2016) that may last for around seven years and may last longer if you don’t use the light too much. You can obtain its battery easily at any watchmaker or jeweller shop.


The strap is very light, soft and flexible. Made of resin, the strap is perfect for any kind of indoor and outdoor activity. Its replacement straps are available at most, if not all, watchmakers’ shops due to its popularity.

casio f91w replacement bandCasio F91w Replacement Band

We have sold and repaired thousands of the Casio F91W watch at our workshop. We are still selling it and d0 recommend it to others. Its light is emitted from a tiny bulb. This bulb has been used before in our workshop to test watch batteries; it will not light up if the battery is down. I will show you how to do it in another article.

Make sure you get the original one, as there are many replicas on the market. You can distinguish the fake ones from the original ones by their bigger back plate. Moreover, their screws are non-stainless and corrodes rapidly. And besides, they are not waterproof.

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