Casio F-91W

Long-term owners

The CR2016 battery last 5+ YEARS , replacements are < $2.

Sep 2026 · comment

Casio's classic F91W often lasts more than 10 years

Mar 2026 · comment

Good chance it will still be produced 30 years from now, too, so if you lose it or break it you can get a new one.

Sep 2026 · comment

What hackers pick instead

• Casio watchPeople recommend Casio digital watches for battery life measured in years, low price and simple, durable use. Critics say the backlight is weak and the interface is hard to use.49recommend
• Casio G-ShockPeople recommend it for accurate, durable, low-maintenance timekeeping and good value for the price. The most common caveat is that it is bulky.43recommend
• Casio F-B100WFans praise its simple classic design, long two-year battery life and reliable time, though it lacks notifications and a usable app.40recommend
• Casio Wave CeptorPeople recommend it for a solar, radio-controlled titanium watch that never needs batteries or setting and keeps accurate time.5recommend
• Casio F-105WA successor to the F-91W that people prefer for its better backlight over the older Illuminator model. The most common caveat is a lower-contrast display that is harder to read in daylight.5recommend

Every quote

The 40 most detailed of 62 comments. Each links to the original.

1. I love the F91-W. I've owned a few of them. Each one had the same problem; the band would crack and break before the battery died.

   Mixed · Aug 2026 · in “New Casio F-B100W – Upgrade to the iconic F-91W after 40 years”

2. F-91W still on its first battery. It's not a great flashlight, but it allows me to find back into bed and not run into anything

   Recommends · Aug 2026 · in “New Casio F-B100W – Upgrade to the iconic F-91W after 40 years”

3. The watch is a favorite of conscripts and anyone else the world over, that needs a sturdy timepiece as cheap as possible.

   Recommends · Nov 2025 · in “The history of Casio watches”

4. Too bad they're so flimsy, I wore one for a week but must have bumped it against something and broke the glass

   Mixed · Oct 2026 · in “Casio Watches of the 1980s”

5. Well I think the F-91 is durable, it's probably not repaired as much as discarded as it is cheap.

   Recommends · Feb 2026 · in “Toyotas and Terrorists: "Why are ISIS's trucks better than ours?"”

6. Super functional, you're not scared of damaging it, because A) You can't and B) it's like $25.

   Recommends · Nov 2025 · in “The history of Casio watches”

7. The point of the F-91W is that is a dead simple digital watch that you can get for $10.

   Recommends · Aug 2026 · in “New Casio F-B100W – Upgrade to the iconic F-91W after 40 years”

8. I really like my F91W case with a Sensor Watch Pro board and accelerometer sensor.

   Recommends · Aug 2026 · in “New Casio F-B100W – Upgrade to the iconic F-91W after 40 years”

9. check out sensorwatch.net or other mods that may exist for the Casio F-91W

   Recommends · Nov 2025 · in “Core Devices keeps stealing our work”

10. I really like my new F91W modded by CW&T, embedded in a brick of resin

    Recommends · Mar 2026 · in “I love my dumb watches”

11. I used and abused it every day since then. It never skipped a beat.

    Recommends · Jan 2026 · in “Tech Is Fun Again: The Tech Monoculture Is Finally Breaking”

12. Casio figured out that cheap and durable isn't a contradiction.

    Recommends · Aug 2026 · in “New Casio F-B100W – Upgrade to the iconic F-91W after 40 years”

13. standardized, rugged, reliable, and repairable technology

    Recommends · Feb 2026 · in “Toyotas and Terrorists: "Why are ISIS's trucks better than ours?"”

14. I think a $30 Casio F91W looks better than an Apple Watch

    Recommends · Aug 2026 · in “My phone detects going on a run as "someone snatching my phone and running off"”

15. The CR2016 battery last 5+ YEARS , replacements are < $2.

    Recommends · Sep 2026 · in “iPhone Duo”

16. I have a hard time wearing it due to the tiny strap

    Mixed · Aug 2026 · in “New Casio F-B100W – Upgrade to the iconic F-91W after 40 years”

17. Casio's classic F91W often lasts more than 10 years

    Recommends · Mar 2026 · in “I love my dumb watches”

18. It has a thriving hacker community built around it.

    Mixed · Apr 2026 · in “The Last Quiet Thing”

19. the backlight is just terrible

    Mixed · Aug 2026 · in “New Casio F-B100W – Upgrade to the iconic F-91W after 40 years”

20. The backlight button is also questionable, because it's not entirely clear what you're suppose to gain

    Criticizes · Aug 2026 · in “New Casio F-B100W – Upgrade to the iconic F-91W after 40 years”

21. In pitch black, it maybe illuminates 2/3 of the screen for me.

    Criticizes · Aug 2026 · in “New Casio F-B100W – Upgrade to the iconic F-91W after 40 years”

22. its so small, it barely fit on my wrist

    Criticizes · Aug 2026 · in “New Casio F-B100W – Upgrade to the iconic F-91W after 40 years”

23. the F-91W has a really small strap

    Criticizes · Aug 2026 · in “New Casio F-B100W – Upgrade to the iconic F-91W after 40 years”

24. terrible backlight on the F-91W

    Criticizes · Aug 2026 · in “New Casio F-B100W – Upgrade to the iconic F-91W after 40 years”

25. Good chance it will still be produced 30 years from now, too, so if you lose it or break it you can get a new one.

    Recommends · Sep 2026 · in “iPhone Duo”

26. The final result isn't pretty, it would have been way cooler if the whole thing had fitted inside the watch

    Mixed · Jan 2026 · in “I hacked Casio F-91W digital watch”

27. Watch has everything I ever cared about - Date, Time, Alarms, Light, Stopwatch, water resistance.

    Recommends · Sep 2026 · in “iPhone Duo”

28. You can buy one. People still make clothes, pencils, cutlery, automatic watches, furniture

    Recommends · Apr 2026 · in “The Last Quiet Thing”

29. I wear it daily, as well as with my suit given how stylish it is in its simplicity.

    Recommends · Aug 2026 · in “New Casio F-B100W – Upgrade to the iconic F-91W after 40 years”

30. The Casio F-91W is the "FlipPhone" of watches. Going Retro on all our electronics.

    Recommends · Sep 2026 · in “iPhone Duo”

31. Like a Casio F-91W is a great watch but it is a fundamentally different category

    Recommends · Sep 2026 · in “iPhone Duo”

32. You could look at these two which are the original f-91 with minimal faceplate

    Recommends · Aug 2026 · in “New Casio F-B100W – Upgrade to the iconic F-91W after 40 years”

33. I have been wearing my Casio F91W for so long I can't even remember buying it

    Recommends · Aug 2026 · in “Pixel Watch 5”

34. I'm a huge fan of the Casio F-91W, have two of them on my desk right now.

    Recommends · Aug 2026 · in “New Casio F-B100W – Upgrade to the iconic F-91W after 40 years”

35. UNESCO should declare the F-91W a part of humanity's cultural heritage.

    Recommends · Nov 2025 · in “The history of Casio watches”

36. the F-91 is better for urban conditions where there's always light

    Recommends · Oct 2026 · in “Casio Watches of the 1980s”

37. The world's most sold digital watch. Widely available since 1989.

    Recommends · Jan 2026 · in “I hacked Casio F-91W digital watch”

38. my current favourite is the JDM yellow (original style) LCD F-91W

    Recommends · Nov 2025 · in “The history of Casio watches”

39. Still remember that cute little beep for the alarm/adjustments.

    Recommends · Sep 2026 · in “iPhone Duo”

40. well designed enough that you actually want to keep it forever

    Recommends · Sep 2026 · in “iPhone Duo”