# Casio F-91W

47 Hacker News commenters recommended Casio F-91W and 7 criticized it, November 2025 to November 2026. It was recommended in 10 of 13 months; owners who said how long report a median of 3 years (7 owners). It meets the Hacker Approved badge rule.

**Verdict:** Cheap, simple, and durable digital watch that often runs for years on one battery, with a strong mod community. Critics say the backlight is weak and the strap is small.

## Why people recommend it

- Durable and reliable (6 comments): "Well I think the F-91 is durable, it's probably not repaired as much as discarded as it is cheap." ([source](https://news.ycombinator.com/item?id=46968160)) "Super functional, you're not scared of damaging it, because A) You can't and B) it's like $25." ([source](https://news.ycombinator.com/item?id=45891996)) "I used and abused it every day since then. It never skipped a beat." ([source](https://news.ycombinator.com/item?id=46741866))
- Cheap to buy and replace (6 comments): "The watch is a favorite of conscripts and anyone else the world over, that needs a sturdy timepiece as cheap as possible." ([source](https://news.ycombinator.com/item?id=45902244)) "Well I think the F-91 is durable, it's probably not repaired as much as discarded as it is cheap." ([source](https://news.ycombinator.com/item?id=46968160)) "Super functional, you're not scared of damaging it, because A) You can't and B) it's like $25." ([source](https://news.ycombinator.com/item?id=45891996))
- Battery lasts years (4 comments): "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." ([source](https://news.ycombinator.com/item?id=49369743)) "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" ([source](https://news.ycombinator.com/item?id=49373559)) "The CR2016 battery last 5+ YEARS , replacements are < $2." ([source](https://news.ycombinator.com/item?id=49633764))
- Strong hacker and mod community (4 comments): "I really like my F91W case with a Sensor Watch Pro board and accelerometer sensor." ([source](https://news.ycombinator.com/item?id=49366056)) "check out sensorwatch.net or other mods that may exist for the Casio F-91W" ([source](https://news.ycombinator.com/item?id=45963046)) "Casio's classic F91W often lasts more than 10 years" ([source](https://news.ycombinator.com/item?id=47462701))

## What people warn about

- Weak backlight (4 comments): "The backlight button is also questionable, because it's not entirely clear what you're suppose to gain" ([source](https://news.ycombinator.com/item?id=49371309)) "In pitch black, it maybe illuminates 2/3 of the screen for me." ([source](https://news.ycombinator.com/item?id=49373015)) "terrible backlight on the F-91W" ([source](https://news.ycombinator.com/item?id=49363508))
- Tiny strap (3 comments): "I have a hard time wearing it due to the tiny strap" ([source](https://news.ycombinator.com/item?id=49369199)) "its so small, it barely fit on my wrist" ([source](https://news.ycombinator.com/item?id=49367053)) "the F-91W has a really small strap" ([source](https://news.ycombinator.com/item?id=49368563))
- Band and glass break (2 comments): "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." ([source](https://news.ycombinator.com/item?id=49369743)) "Too bad they're so flimsy, I wore one for a week but must have bumped it against something and broke the glass" ([source](https://news.ycombinator.com/item?id=50319827))

## Alternatives hackers recommend

- [Casio watch](https://hackerapproved.com/p/casio-watch.md): 49 recommend
- [Casio G-Shock](https://hackerapproved.com/p/casio-g-shock.md): 43 recommend
- [Casio F-B100W](https://hackerapproved.com/p/casio-f-b100w.md): 40 recommend
- [Casio Wave Ceptor](https://hackerapproved.com/p/casio-wave-ceptor.md): 5 recommend
- [Casio F-105W](https://hackerapproved.com/p/casio-f-105w.md): 5 recommend

## Where to get it

- [See price on Amazon](https://www.amazon.com/s?k=Casio+F-91W+digital+watch&tag=YOURTAG-20) (affiliate link)
- [Official site](https://www.casio.com/us/)

## Cite as

Hacker Approved, "Casio F-91W", https://hackerapproved.com/p/casio-f-91w/ (counts from 1,795,640 Hacker News comments, November 2025 to November 2026).